2024 |
Aas, W., Fagerli, H., Alastuey, A., Cavalli, F., Degorska, A., Feigenspan, S., et al. (2024). Trends In Air Pollution In Europe, 2000-2019. Aerosol And Air Quality Research, 242(4).
Abstract: This Paper Encompasses An Assessment Of Air Pollution Trends In Rural Environments In Europe Over The 2000-2019 Period, Benefiting From Extensive Long-Term Observational Data From The Emep Monitoring Network And Emep Msc-W Model Computations. The Trends In Pollutant Concentrations Align With The Decreasing Emission Patterns Observed Throughout Europe. Annual Average Concentrations Of Sulfur Dioxide, Particulate Sulfate, And Sulfur Wet Deposition Have Shown Consistent Declines Of 3-4% Annually Since 2000. Similarly, Oxidized Nitrogen Species Have Markedly Decreased Across Europe, With An Annual Reduction Of 1.5-2% In Nitrogen Dioxide Concentrations, Total Nitrate In The Air, And Oxidized Nitrogen Deposition. Notably, Emission Reductions And Model Predictions Appear To Slightly Surpass The Observed Declines In Sulfur And Oxidized Nitrogen, Indicating A Potential Overestimation Of Reported Emission Reductions. Ammonia Emissions Have Decreased Less Compared To Other Pollutants Since 2000. Significant Reductions In Particulate Ammonium Have However, Been Achieved Due To The Impact Of Reductions In Sox And Nox Emissions. For Ground Level Ozone, Both The Observed And Modelled Peak Levels In Summer Show Declining Trends, Although The Observed Decline Is Smaller Than Modelled. There Have Been Substantial Annual Reductions Of 1.8% And 2.4% In The Concentrations Of Pm10 And Pm2.5, Respectively. Elemental Carbon Has Seen A Reduction Of Approximately 4.5% Per Year Since 2000. A Similar Reduction For Organic Carbon Is Only Seen In Winter When Primary Anthropogenic Sources Dominate. The Observed Improvements In European Air Quality Emphasize The Importance Of Comprehensive Legislations To Mitigate Emissions.
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Amato, F., Van Drooge, B., Jaffrezo, J., Favez, O., Colombi, C., Cuccia, E., et al. (2024). Aerosol Source Apportionment Uncertainty Linked To The Choice Of Input Chemical Components. Environment International, 1841.
Abstract: For A Positive Matrix Factorization (Pmf) Aerosol Source Apportionment (Sa) Studies There Is No Standard Procedure To Select The Most Appropriate Chemical Components To Be Included In The Input Dataset For A Given Site Typology, Nor Specific Recommendations In This Direction. However, These Choices Are Crucial For The Final Sa Outputs Not Only In Terms Of Number Of Sources Identified But Also, And Consequently, In The Source Contributions Estimates. In Fact, Pmf Tends To Reproduce Most Of Pm Mass Measured Independently And Introduced As A Total Variable In The Input Data, Regardless Of The Percentage Of Pm Mass Which Has Been Chemically Characterized, So That The Lack Of Some Specific Source Tracers (E.G. Levoglucosan) Can Potentially Affect The Results Of The Whole Source Apportionment Study. The Present Study Elaborates Further On The Same Concept, Evaluating Quantitatively The Impact Of Lacking Specific Sources' Tracers On The Whole Source Apportionment, Both In Terms Of Identified Sources And Source Contributions. This Work Aims To Provide First Recommendations On The Most Suitable And Critical Components To Be Included In Pmf Analyses In Order To Reduce Pmf Output Uncertainty As Much As Possible, And Better Represent The Most Commons Pm Sources Observed In Many Sites In Western Countries. To This Aim, We Performed Three Sensitivity Analyses On Three Different Datasets Across Eu, Including Extended Sets Of Organic Tracers, In Order To Cover Different Types Of Urban Conditions (Mediterranean, Continental, And Alpine), Source Types, And Pm Fractions. Our Findings Reveal That The Vehicle Exhaust Source Resulted To Be Less Sensitive To The Choice Of Analytes, Although Source Contributions Estimates Can Deviate Significantly Up To 44 %. On The Other Hand, For The Detection Of The Non-Exhaust One Is Clearly Necessary To Analyze Specific Inorganic Elements. The Choice Of Not Analysing Non-Polar Organics Likely Causes The Loss Of Separation Of Exhaust And Non-Exhaust Factors, Thus Obtaining A Unique Road Traffic Source, Which Provokes A Significant Bias Of Total Contribution. Levoglucosan Was, In Most Cases, Crucial To Identify Biomass Burning Contributions In Milan And In Barcelona, In Spite Of The Presence Of Pahs In Barcelona, While For The Case Of Grenoble, Even Discarding Levoglucosan, The Presence Of Pahs Allowed Identifying The Bb Factor. Modifying The Rest Of Analytes Provoke A Systematic Underestimation Of Biomass Burning Source Contributions. Sia Factors Resulted To Be Generally Overestimated With Respect To The Base Case Analysis, Also In The Case That Ions Were Not Included In The Pmf Analysis. Trace Elements Were Crucial To Identify Shipping Emissions (V And Ni) And Industrial Sources (Pb, Ni, Br, Zn, Mn, Cd And As). When Changing The Rest Of Input Variables, The Uncertainty Was Narrow For Shipping But Large For Industrial Processes. Major And Trace Elements Were Also Crucial To Identify The Mineral/Soil Factor At All Cities. Biogenic Soa And Anthropogenic Soa Factors Were Sensitive To The Presence Of Their Molecular Tracers, Since The Availability Of Oc Alone Is Unable To Separate A Soa Factor. Arabitol And Sorbitol Were Crucial To Detecting Fungal Spores While Odd Number Of Higher Alkanes (C27 To C31) For Plant Debris.
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Amory, C., Buizert, C., Buzzard, S., Case, E., Clerx, N., Culberg, R., et al. (2024). Firn On Ice Sheets. Nature Reviews Earth & Environment, .
Abstract: Most Of The Greenland And Antarctic Ice Sheets Are Covered With Firn – The Transitional Material Between Snow And Glacial Ice. Firn Is Vital For Understanding Ice-Sheet Mass Balance And Hydrology, And Palaeoclimate. In This Review, We Synthesize Knowledge Of Firn, Including Its Formation, Observation, Modelling And Relevance To Ice Sheets. The Refreezing Of Meltwater In The Pore Space Of Firn Currently Prevents 50% Of Meltwater In Greenland From Running Off Into The Ocean And Protects Antarctic Ice Shelves From Catastrophic Collapse. Continued Atmospheric Warming Could Inhibit Future Protection Against Mass Loss. For Example, Warming In Greenland Has Already Contributed To A 5% Reduction In Firn Pore Space Since 1980. All Projections Of Future Firn Change Suggest That Surface Meltwater Will Have An Increasing Impact On Firn, With Melt Occurring Tens To Hundreds Of Kilometres Further Inland In Greenland, And More Extensively On Antarctic Ice Shelves. Although Progress In Observation And Modelling Techniques Has Led To A Well-Established Understanding Of Firn, The Large Uncertainties Associated With Meltwater Percolation Processes (Refreezing, Ice-Layer Formation And Storage) Must Be Reduced Further. A Tighter Integration Of Modelling Components (Firn, Atmosphere And Ice-Sheet Models) Will Also Be Needed To Better Simulate Ice-Sheet Responses To Anthropogenic Warming And To Quantify Future Sea-Level Rise. A Firn Layer Covers The Earth'S Ice Sheets. This Review Outlines Techniques To Observe And Model Changes In Firn Properties And Meltwater Retention To Understand How This Firn Layer Will Respond To Climate Change.
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Aroskay, A., Martin, E., Bekki, S., Le Pennec, J., Savarino, J., Temel, A., et al. (2024). Geological Evidence Of Extensive N- Fixation By Volcanic Lightning During Very Large Explosive Eruptions. Proceedings Of The National Academy Of Sciences Of The United States Of America, 1211(7).
Abstract: Most Of The Nitrogen (N) Accessible For Life Is Trapped In Dinitrogen (N2), The Most Stable Atmospheric Molecule. In Order To Be Metabolized By Living Organisms, N2 Has To Be Converted Into Biologically Assimilable Forms, So – Called Fixed N. Nowadays, Nearly All The N- Fixation Is Achieved Through Biological And Anthropogenic Processes. However, In Early Prebiotic Environments Of The Earth, N- Fixation Must Have Occurred Via Natural Abiotic Processes. One Of The Most Invoked Processes Is Electrical Discharges, Including From Thunderstorms And Lightning Associated With Volcanic Eruptions. Despite The Frequent Occurrence Of Volcanic Lightning During Explosive Eruptions And Convincing Laboratory Experimentation, No Evidence Of Substantial N- Fixation Has Been Found In Any Geological Archive. Here, We Report On The Discovery Of A Significant Amount Of Nitrate In Volcanic Deposits From Neogene Caldera- Forming Eruptions, Which Are Well Correlated With The Concentrations Of Species Directly Emitted By Volcanoes (Sulfur, Chlorine). The Multi- Isotopic Composition (Delta 18O, Delta 17O) Of The Nitrates Reveals That They Originate From The Atmospheric Oxidation Of Nitrogen Oxides Formed By Volcanic Lightning. According To These First Geological Volcanic Nitrate Archive, We Estimate That, On Average, About 60 Tg Of N Can Be Fixed During A Large Explosive Event. Our Findings Hint At A Unique Role Potentially Played By Subaerial Explosive Eruptions In Supplying Essential Ingredients For The Emergence Of Life On Earth.
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Bacer, S., Beaumet, J., Ménégoz, M., Gallée, H., Le Bouëdec, E., & Staquet, C. (2024). Impact Of Climate Change On Persistent Cold-Air Pools In An Alpine Valley During The 21St Century. Weather And Climate Dynamics, 5(1), 211–229.
Abstract: When Anticyclonic Conditions Persist Over Mountainous Regions In Winter, Cold-Air Pools (I.E. Thermal Inversions) Develop In Valleys And Persist From A Few Days To A Few Weeks. During These Persistent Cold-Air Pool (Pcap) Episodes The Atmosphere Inside The Valley Is Stable And Vertical Mixing Is Prevented, Promoting The Accumulation Of Pollutants Close To The Valley Bottom And Worsening Air Quality. The Purpose Of This Paper Is To Address The Impact Of Climate Change On Pcaps Until The End Of This Century For The Alpine Grenoble Valleys.The Long-Term Projections Produced With The General Circulation Model Mpi (From The Max Planck Institute) Downscaled Over The Alps With The Regional Climate Model Mar (Modele Atmospherique Regional) Are Used To Perform A Statistical Study Of Pcaps Over The Period 1981-2100. The Trends Of The Main Characteristics Of Pcaps, Namely Their Intensity, Duration, And Frequency, Are Investigated For Two Future Scenarios, Ssp2-4.5 And Ssp5-8.5. We Find That The Intensity Of Pcaps Displays A Statistically Significant Decreasing Trend For The Ssp5-8.5 Scenario Only. This Decay Is Explained By The Fact That Air Temperature Over The Century Increases More At 2 M Above The Valley Bottom Than In The Free Air At Mid-Altitudes In The Valley; This Might Be Due To The Increase Of Specific Humidity Near The Ground.The Vertical Structure Of Two Pcaps, One In The Past And One Around 2050, Is Next Investigated In Detail. For This Purpose, The Wrf (Weather Research And Forecasting) Model, Forced By Mar For The Worst-Case Scenario (Ssp5-8.5), Is Used At A High Resolution (111 M). The Pcap Episodes Are Carefully Selected From The Mar Data So That A Meaningful Comparison Can Be Performed. The Future Episode Is Warmer At All Altitudes Than The Past Episode (By At Least 4 Circle C) And Displays A Similar Inversion Height, Which Are Very Likely Generic Features Of Future Pcaps. The Selected Episodes Also Have Similar Along-Valley Wind But Different Stability, With The Future Episode Being More Stable Than The Past Episode.Overall, This Study Shows That The Atmosphere In The Grenoble Valleys During Pcap Episodes Tends To Be Slightly Less Stable In The Future Under The Ssp5-8.5 Scenario, And Statistically Unchanged Under The Ssp2-4.5 Scenario, But That Very Stable Pcaps Can Still Form.
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Benning, L., Wagner, D., Larose, C., Gunde-Cimerman, N., & Haeggblom, M. (2024). Editorial: Thematic Issue On Polar And Alpine Microbiology. Fems Microbiology Ecology, 1001(4).
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Bhowmick, S., Chaudhary, A., Jishad, M., Seemanth, M., Utkarsh, Agarwal, N., et al. (2024). How Useful Are Mispointing Phase Saral/Altika Geophysical Products For Ocean Applications? Advances In Space Research, 737(1), 414–425.
Abstract: Saral/Altika, The First Microwave Altimeter Operating At Ka -Band Frequency, Recently Completed Nine Years Of Operations In Orbit. During These Years, It Has Catered To Many Applications Related To Operational Oceanography, Climate Sciences, Hydrology And Cryosphere. More Specifically, In Oceanography, Saral Has Contributed Immensely To Operational Wave And Circulation Modelling, Eddy Detection/Tracking, Ocean Current Generation And Many More. However, Since Feb 2019, Saral Has Moved From The Drifting Phase (Dp) To The Mispointing Phase (Mp) Due To The Malfunctioning Of The Star Sensor Of The Spacecraft. In This Study, We Analyse The Instrument'S Performance And Its Waveforms During Its Ongoing Mp. We Find Out That During The Mp, Significant Wave Height (Swh) Measurements Are Anomalously High Between 18 And 24 M, And Wind Speed Measurements Are Between 16 And 19 M/S. In Sea Surface Height Anomaly (Ssha), There Is A Steady Rise In Negative Values During The Mp. In The Return Waveform, -15% Degradation In Brown -Type Waveforms In The Open Ocean Region Is Noticed. These Changes Significantly Impact The Saral Applications. Two Important Applications Of Wave Forecast And Eddy Detection Are Discussed Here As Examples. Following This, We Also Recommend Using Provided Quality Flags So That The Data Can Be Further Explored For Various Ocean Applications. (C) 2023 Cospar. Published By Elsevier B.V. All Rights Reserved.
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Bodart, G., Le Coz, J., Jodeau, M., & Hauet, A. (2024). Quantifying And Reducing The Operator Effect In Lspiv Discharge Measurements. Water Resources Research, 606(2).
Abstract: Operator Choices, Both In Acquiring The Video And Data And In Processing Them, Can Be A Prominent Source Of Error In Image-Based Velocimetry Methods Applied To River Discharge Measurements. The Large Scale Particle Image Velocimetry (Lspiv) Is Known To Be Sensitive To The Parameters And Computation Choices Set By The User, But No Systematic Comparisons With Discharge References Or Intercomparisons Have Been Conducted Yet To Evaluate This Operator Effect In Lspiv. In This Paper, An Analysis Of A Video Gauging Intercomparison, The Video Globe Challenge 2020, Is Proposed To Evaluate Such Operator Effect. The Analysis Is Based On The Gauging Reports Of The 15 To 23 Participants Using The Fudaa-Lspiv Software And Intents To Identify The Most Sensitive Parameters For The Eight Videos. The Analysis Highlighted The Significant Impact Of The Time Interval, The Grid Points And The Filters On The Lspiv Discharge Measurements. These Parameters Are Often Inter-Dependent And Should Be Correctly Set Together To Strongly Reduce The Discharge Errors. Based On The Results, Several Automated Tools Were Proposed To Reduce The Operator Effect. These Tools Consist Of Several Parameter Assistants To Automatically Set The Orthorectification Resolution, The Grid And The Time Interval, And Of A Sequence Of Systematic And Automatic Filters To Ensure Reliable Velocity Measurements Used For Discharge Estimation. The Application Of The Assisted Lspiv Workflow Using The Proposed Tools Leads To Significant Improvements Of The Discharge Measurements With Strong Reductions Of The Inter-Participant Variability. On The Eight Videos, The Mean Interquartile Range Of The Discharge Errors Is Reduced From 17% To 5% And The Mean Discharge Bias Is Reduced From -9% To 1% With The Assisted Lspiv Workflow. The Remaining Inter-Participant Variability Is Mainly Due To The User-Defined Surface Velocity Coefficient Alpha.
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Buri, P., Fatichi, S., Shaw, T., Fyffe, C., Miles, E., Mccarthy, M., et al. (2024). Land Surface Modeling Informed By Earth Observation Data: Toward Understanding Blue-Green-White Water Fluxes In High Mountain Asia. Geo-Spatial Information Science, .
Abstract: Mountains Are Important Suppliers Of Freshwater To Downstream Areas, Affecting Large Populations In Particular In High Mountain Asia (Hma). Yet, The Propagation Of Water From Hma Headwaters To Downstream Areas Is Not Fully Understood, As Interactions In The Mountain Water Cycle Between The Cryo-, Hydro- And Biosphere Remain Elusive. We Review The Definition Of Blue And Green Water Fluxes As Liquid Water That Contributes To Runoff At The Outlet Of The Selected Domain (Blue) And Water Lost To The Atmosphere Through Vapor Fluxes, That Is Evaporation From Water, Ground, And Interception Plus Transpiration (Green) And Propose To Add The Term White Water To Account For The (Often Neglected) Evaporation And Sublimation From Snow And Ice. We Provide An Assessment Of Models That Can Simulate The Cryo-Hydro-Biosphere Continuum And The Interactions Between Spheres In High Mountain Catchments, Going Beyond Disciplinary Separations. Land Surface Models Are Uniquely Able To Account For Such Complexity, Since They Solve The Coupled Fluxes Of Water, Energy, And Carbon Between The Land Surface And Atmosphere. Due To The Mechanistic Nature Of Such Models, Specific Variables Can Be Compared Systematically To Independent Remote Sensing Observations – Providing Vital Insights Into Model Accuracy And Enabling The Understanding Of The Complex Watersheds Of Hma. We Discuss Recent Developments In Spaceborne Earth Observation Products That Have The Potential To Support Catchment Modeling In High Mountain Regions. We Then Present A Pilot Study Application Of The Mechanistic Land Surface Model Tethys & Chloris To A Glacierized Watershed In The Nepalese Himalayas And Discuss The Use Of High-Resolution Earth Observation Data To Constrain The Meteorological Forcing Uncertainty And Validate Model Results. We Use These Insights To Highlight The Remaining Challenges And Future Opportunities That Remote Sensing Data Presents For Land Surface Modeling In Hma.
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Camman, J., Chazeau, B., Marchand, N., Durand, A., Gille, G., Lanzi, L., et al. (2024). Oxidative Potential Apportionment Of Atmospheric Pm1: A New Approach Combining High-Sensitive Online Analysers For Chemical Composition And Offline Op Measurement Technique. Atmospheric Chemistry And Physics, 242(5), 3257–3278.
Abstract: Source Apportionment Models Were Widely Used To Successfully Assign Highly Time-Resolved Aerosol Data To Specific Emissions And/Or Atmospheric Chemical Processes. These Techniques Are Necessary For Targeting The Sources Affecting Air Quality And For Designing Effective Mitigation Strategies. Moreover, Evaluation Of The Toxicity Of Airborne Particulate Matter Is Important Since The Classically Measured Particulate Matter (Pm) Concentrations Appear Insufficient For Characterizing The Impact On Human Health. Oxidative Potential (Op) Measurement Has Recently Been Developed To Quantify The Capability Of Pm To Induce An Oxidative Imbalance In The Lungs. As A Result, This Measurement Unit Could Be A Better Proxy Than Pm Mass Concentration To Represent Pm Toxicity. In The Present Study, Two Source Apportionment Analyses Were Performed Using Positive Matrix Factorization (Pmf) From Organic Aerosol (Oa) Mass Spectra Measured At A 15 Min Time Resolution Using A Time-Of-Flight Aerosol Chemical Speciation Monitor (Tof-Acsm) And From 19 Trace Elements Measured On An Hourly Basis Using An Online Metal Analyser (Xact 625I). The Field Measurements Were Carried Out In Summer 2018. While It Is Common To Perform Pmf Studies Individually On Acsms And More Recently On Xact Datasets, Here We Used A Two-Step Methodology Leading To A Complete Pm 1 Source Apportionment. The Outputs From Both Oa Pmf And Xact Pmf, The Inorganic Species Concentrations From The Acsm, And The Black Carbon (Bc) Fractions (Fossil Fuel And Wood Burning) Measured Using An Aethalometer (Ae33) Were Gathered Into A Single Dataset And Subjected To A Combined Pmf Analysis. Overall, Eight Factors Were Identified, Each Of Them Corresponding To A More Precise Source Than Performing Single Pmf Analyses. The Results Show That Besides The High Contribution Of Secondary Ammonium Sulfate (28 %) And Organic Nitrate (19 %), About 50 % Of Pm 1 Originated From Distinct Combustion Sources, Including Emissions From Traffic, Shipping, Industrial Activities, Cooking, And Biomass Burning. Simultaneously, Pm 1 Filters Were Collected During The Experimental Period On A 4 H Sampling Basis. On These Filters, Two Acellular Op Assays Were Performed (Dithiothreitol; Op Dtt And Ascorbic Acid; Op Aa ) And An Inversion Method Was Applied On Factors Issued From All Pmfs To Assess The Contribution Of The Pm Sources To The Op. This Work Highlights The Sensitivity Of Op Aa To Industrial And Dust Resuspension Sources And Those Of Op Dtt To Secondary Ammonium Sulfate, Shipping, And Biomass Burning.
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Cantera, I., Carteron, A., Guerrieri, A., Marta, S., Bonin, A., Ambrosini, R., et al. (2024). The Importance Of Species Addition 'Versus' Replacement Varies Over Succession In Plant Communities After Glacier Retreat. Nature Plants, .
Abstract: The Mechanisms Underlying Plant Succession Remain Highly Debated. Due To The Local Scope Of Most Studies, We Lack A Global Quantification Of The Relative Importance Of Species Addition 'Versus' Replacement. We Assessed The Role Of These Processes In The Variation (Beta-Diversity) Of Plant Communities Colonizing The Forelands Of 46 Retreating Glaciers Worldwide, Using Both Environmental Dna And Traditional Surveys. Our Findings Indicate That Addition And Replacement Concur In Determining Community Changes In Deglaciated Sites, But Their Relative Importance Varied Over Time. Taxa Addition Dominated Immediately After Glacier Retreat, As Expected In Harsh Environments, While Replacement Became More Important For Late-Successional Communities. These Changes Were Aligned With Total Beta-Diversity Changes, Which Were More Pronounced Between Early-Successional Communities Than Between Late-Successional Communities (>50 Yr Since Glacier Retreat). Despite The Complexity Of Community Assembly During Plant Succession, The Observed Global Pattern Suggests A Generalized Shift From The Dominance Of Facilitation And/Or Stochastic Processes In Early-Successional Communities To A Predominance Of Competition Later On.
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Chahrour, N., Bérenguer, C., & Tacnet, J. (2024). Incorporating Cascading Effects Analysis In The Maintenance Policy Assessment Of Torrent Check Dams Against Torrential Floods. Reliability Engineering & System Safety, 2432.
Abstract: In Mountainous Regions, Protection Infrastructures Designed To Mitigate The Impacts Of Torrential Floods Often Consist Of A Complex System Of Several Structural Components (Check Dams). Over Time, The Efficacy Of This System In Protecting Downstream Assets Diminishes As The Structural Components Deteriorate. The Extent Of Deterioration Is Influenced By The Interdependencies Between The Failure Modes Of Individual Components, As Well As Those Between Multiple Components Of The System. Understanding And Quantifying The Chain Of Failure Events, Known As Cascading Effects, Is A Critical Scientific Challenge That Remains Largely Unexplored. In This Study, We Propose A Novel Approach That Employs Physics-Based Models To Examine The Deterioration Of A Series Of Check Dams Over Time, While Considering Failure Dependencies And Bidirectional Interactions Between Consecutive Dams. The Results Obtained From This Approach Reveals That The Absence Of A Downstream Dam Accelerates The Deterioration Rate Of Upstream Dams, While Its Presence Serves To Stabilize Them. We Further Incorporate Stochastic Deterioration And Maintenance Processes Using Stochastic Petri Nets To Support Decision-Making Regarding Maintenance Actions For Each Dam, While Also Considering Economic Factors. Strategies Involving Minor Operations Achieved Cost-Effectiveness And Prolonged Satisfactory Performance Of The Dams, With Notable Impacts From Upstream And Downstream Dam Presence On Maintenance Costs. We Illustrate Our Approach Using A Case Study Of The Faucon Torrent In France, Where We Model The Deterioration Of Three Consecutive Check Dams Subjected To Torrential Floods Over A Period Of 100 Years.
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Chahrour, N., Piton, G., Tacnet, J., & Bérenguer, C. (2024). A Surrogate Deterioration Model Of Debris Retention Systems Towards Cost-Effective Maintenance Strategies And Increased Protection Efficacy. Engineering Structures, 3003.
Abstract: Protection Systems Are Usually Implemented In Mountains Aiming To Resist Natural Dangerous Phenomena. As Any Other Critical Infrastructure, Protection Systems Should Always Withstand And Operate Efficiently As They Guarantee The Safety Of People And Protect Socio-Economic Assets. However, The Efficacy Of These Systems Decreases With The Increase Of The Deterioration Level Of The Interdependent Components, Which Constitute Them. To Provide Desirable Operation Over Their Lifetime, The Management Of Protection Systems Is Of Paramount Importance. A Major Key Issue In Such Critical Infrastructure Management Is To Optimize The Cost Effectiveness Of Maintenance Actions While Maintaining A Sufficient Protection Efficacy. This Study Proposes A Decision-Aiding Model To Assess Different Maintenance Strategies Applied To A Protection System Against Debris Flows. The Model Is Constructed Using Physics-Based Stochastic Petri Nets. It Incorporates (1) A Stochastic Deterioration Model, Which Is A Surrogate Model Of A Physics-Based Model Developed For Building Deterioration Trajectories Of The System And (2) Maintenance Model That Permits Assessing The Cost And Efficiency Of Maintenance Strategies. This Study Addresses The Case Of A Debris Retention System, In Which The Progressive Filling Of Its Basin By Debris Materials Is Modeled. This Is Followed By Assessing Several Maintenance Strategies Concerning The Cleaning Of The Basin. A Simple Sensitivity Analysis Is Also Carried Out In Order To Check The Effect Of The Uncertainty That Invades The Model'S Inputs On Maintenance Decisions. A Numerical Analysis Is Performed Using Real Data Of The Retention System Located In The Claret Torrent In France And Subjected To Debris Flows Over A Period Of 50 Years.
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Charrondiere, C., Hopfinger, E., Brun, C., Cohard, J., & Sicart, J. (2024). Evidence Of Strong Wave Turbulence And Of Bolgiano Temperature Spectra In Katabatic Winds On Steep Slopes. Physics Of Fluids, 363(2).
Abstract: The Katabatic Winds On Steep Slopes Investigated In The Present Study Reveal A Novel Spectral Behavior, Observed In The Outer Part Of The Jet. At Low Wavenumbers, The One-Dimensional (1D) Velocity Spectra Show Evidence Of A K(X)(-1) Range For The Three Components Of The Velocity Vector: E-U(K(X)), E-V(K(X)), E-W(K(X)) Proportional To K(X)(-1) [As Well As For The 1D Temperature Spectrum E-Theta(K(X)) Proportional To K(X)(-1)]. This Suggests The Existence Of Strong Wave Turbulence. A Necessary Condition For Strong Wave Turbulence To Be Manifest Is That The Flow Direction Wavenumber, K(X), Extends To Much Lower Values Than The Slope Normal One, K(Z). This Is Satisfied In The Present Field Experiment Where Wave Energy Is Injected At Wavenumber K(X) = K(N) = (N-A Sin Alpha)/(U(J)) Over Bar, While K(Z) Similar To 1/Delta(Z), With N-A The Ambient Stratification, Alpha The Slope Angle, (U(J)) Over Bar The Maximum Wind Velocity, And Delta(Z) The Shear Layer Thickness Of The Jet. In The Inertial Range, The Velocity Spectra Exhibit A Power Law K(X)(-5/3) Over Two Decades, Whereas The Temperature-Buoyancy Spectra Show Evidence Of A – 7/5 Slope In The Buoyancy Sub-Range, Followed By A – 5/3 Slope. The Change In Spectral Slopes Occurs At The Bolgiano Scale L-B That Is Close To The Dougherty-Ozmidov Scale L-Oz. The High Reynolds Number Based On The Taylor Micro-Scale, Re-Lambda Similar To 10(3), Allows Clear Identification Of The Spectral Laws.
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Charton, J., Schimmelpfennig, I., Jomelli, V., Verfaillie, D., Delpech, G., Guillaume, D., et al. (2024). Late Pleistocene Glaciations On The Sub-Antarctic Kerguelen Archipelago: New Evidence From 36Cl Cre Dating And Comparison With Other Southern Mid-Latitude Glacier Records. Quaternary Science Reviews, 3283.
Abstract: Previous Paleo-Glacial Studies On Kerguelen Showed A Singular Pattern Of Holocene Glacier Evolution On This Archipelago In Comparison With Other Southern Mid-Latitude Glacier Records. In This Study, We Aim To Test This Singularity On A Longer Timescale, Based On 26 New In Situ-Produced 36Cl Ages From Pre-Holocene Glaciogeomorphic Features. Samples From Moraine Boulders And Glacially Polished Bedrock Were Extracted At Six Different Sites, Located Near The Port-Aux-Francais Scientific Station (Paf Site), On Longue Island, Australia Island, On The Port-Jeanne D'Arc Peninsula (Pjda Site), On The Gallieni Peninsula At Baie Larose (Blr Site) And The Mcmurdo Island. The Moraine Ages Indicate That Glacier Culminations Occurred During Marine Isotopic Stage 3 (Mis 3) At 42.2 +/- 4.9 Ka On The Paf Site, And During The Global Last Glacial Maximum (Glgm) At 21.5 +/- 3.2 Ka On The Pjda Site And At 21.4 +/- 3.7 Ka And 19.4 +/- 2.6 On Baie Larose Site. This Is The First Time That Late Pleistocene Glacier Culminations Are Evidenced On Kerguelen By Direct Moraine Dating, Thus Allowing Comparison With Other Moraine Records From The Southern Mid-Latitudes. While It Remains Speculative Whether Or Not The Mis 3 Glacial Maximum At -42.2 Ka Is In Phase With Other Glaciers At This Latitude (Due To High Age Uncertainties), The Glgm Glacial Maximum Is Synchronous With That In Other Southern Mid-Latitude Regions. 36Cl Cre Ages Of Glacially Polished Bedrock Surfaces Sampled In Different Locations Of The Archipelago Vary From -39 Ka To -19 Ka. We Interpret These Results As Reflecting Periods Of Deglaciation That Occurred In Between The Two Glacier Culminations And Right After The Glgm On Kerguelen. These Ages Also Suggest That Some Places Of The Archipelago Were Free Of Ice At Least Since – 39 Ka. The Presence Of A Mis 3 Moraine At Paf Site That Has Not Been Obliterated By A Glgm Advance Suggests That The – 42.2 Ka Glacier Extent Was At Least As Large As Glgm Glacial Maxima On The Archipelago. The Glacier Culmination During Mis 3 Being Larger Than That During The Glgm On The Kerguelen Archipelago Matches Observations In Other Southern Mid-Latitude Regions. Late Pleistocene Glacier Culminations On Kerguelen May Have Been In Phase With Cold Temperatures Recorded In Sst Records, Which Suggest A Cooling Around Kerguelen. However, Climate Drivers Responsible For The Larger Mis 3 Glacier Culmination On Kerguelen Still Remain Unclear Even If We Hypothesize That Changes In Precipitation May Have Superimposed On Temperature Changes.
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Chifflet, S., Guyomarc'H, L., Dominutti, P., Heimbürger-Boavida, L., Angeletti, B., Louvat, P., et al. (2024). Seasonal Variations Of Metals And Metalloids In Atmospheric Particulate Matter (Pm2.5) In The Urban Megacity Hanoi. Atmospheric Pollution Research, 151(1).
Abstract: Fine Particulate Matter (Pm2.5) In The Atmosphere Is Of Particular Concern Due To Its Adverse Effects On Human Health And Its Impact On Global Warming. Southeast Asia Is A Hot Spot For Fossil Fuel Combustion With Recurrent Release Of Large Plumes Spreading Over The Ocean And Neighbouring Countries. Due To The Complex Mixture Of Pm2.5, The Atmospheric Sources Contribution Related To Local And Regional Emissions In Hanoi (Northern Vietnam) Is Still Ill-Constrained. Here, We Present A Year-Round Study (November 2019 To December 2020) With Mea-Surements Of 18 Metals And Metalloids (Mm) And Lead Isotopes In The Pm2.5 Fraction To Quantify Weather-Related Atmospheric Inputs And To Assess Risk To Human Health. Anthropogenic Inputs From Fossil Fuel Combustion Accounted For About 80% In Pm2.5. We Found High Pm2.5-Bound Mm Concentrations Often Exceeding National And Global Standards With A Low Risk Of Chronic Inhalation And Carcinogenicity, Mainly Attributable To Cr. During Winter Monsoon (Northeastern Winds), Stable Weather Conditions Led To The Enrichment Of Long-Range Air Mass Transport Of Local Particulate Emissions. During The Summer Monsoon (Southeastern Winds), Warm And Moist Winds Reduced Coal Contribution In Pm2.5. Our Study Highlights The Need For A Strict Implementation Of Policies To Control Hazardous Mm Emissions By Reducing Fossil Fuel Combustion. On The One Hand, Reducing Coal-Related Activities Could Reduce Cr Emissions And Therefore Improve The Risks To Human Health. On The Other Hand, Public Policies Should Encourage Conversion To Green Transport In Order To Reduce Petrol Combustion And Thus Limit Global Warming.
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Clauzel, L., Anquetin, S., Lavaysse, C., Tremoy, G., & Raynaud, D. (2024). West African Operational Daily Solar Forecast Errors And Their Link With Meteorological Conditions. Renewable Energy, 2242.
Abstract: West Africa Is At The Forefront Of Global Environmental Challenges With Its Commitment To Reduce Greenhouse Gas Emissions And Harnessing The Potential Of Renewable Energy, Especially The Promising Solar Power. This Study Evaluates Global Horizontal Irradiance (Ghi) Operational Forecast Errors For The Zagtouli (Burkina-Faso) And Sococim (Senegal) Solar Plants, And Investigates Their Links With Local Meteorological Conditions, Particularly Clouds And Dust Aerosols. Firstly, The Evaluation Of Aerosol Products Indicates That Cams Reanalysis Is Reliable For Assessing Aerosol Optical Depth. We Then Examine The Accuracy Of Three Operational Ghi Forecast Products: The Global Forecast System (Gfs, Ncep), The Integrated Forecast System (Ifs, Ecmwf), And Steadymet (Sm, French Company Steadysun). The Analysis Reveals That Ifs And Sm Outperform Gfs, Sm Having A Slight Advantage Due To Its Probabilistic Nature. Closer Examination Reveals A Significant Relationship Between Ghi Forecast Errors And Local Meteorological Characteristics. These Errors Are More Pronounced During The Wet Season, Primarily Attributed To Cloud Occurrence. Dust Events Play A Secondary Influential Role, Especially During The Dry Season. Correlation Analyses Emphasize The Forecast Errors' Major Link With Cloudiness, While Co-Occurrences Highlight That Dust Aerosol Is A Secondary Factor In Forecast Errors For The Ghi Directly Or For Cloud Representation (Aerosolcloud Interaction).
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Coulon, V., Klose, A., Kittel, C., Edwards, T., Turner, F., Winkelmann, R., et al. (2024). Disentangling The Drivers Of Future Antarctic Ice Loss With A Historically Calibrated Ice-Sheet Model. Cryosphere, 181(2), 653–681.
Abstract: We Use An Observationally Calibrated Ice-Sheet Model To Investigate The Future Trajectory Of The Antarctic Ice Sheet Related To Uncertainties In The Future Balance Between Sub-Shelf Melting And Ice Discharge, On The One Hand, And The Surface Mass Balance, On The Other. Our Ensemble Of Simulations, Forced By A Panel Of Climate Models From The Sixth Phase Of The Coupled Model Intercomparison Project (Cmip6), Suggests That The Ocean Will Be The Primary Driver Of Short-Term Antarctic Mass Loss, Initiating Ice Loss In West Antarctica Already During This Century. The Atmosphere Initially Plays A Mitigating Role Through Increased Snowfall, Leading To An Antarctic Contribution To Global Mean Sea-Level Rise By 2100 Of 6 (-8 To 15) Cm Under A Low-Emission Scenario And 5.5 (-10 To 16) Cm Under A Very High-Emission Scenario. However, Under The Very High-Emission Pathway, The Influence Of The Atmosphere Shifts Beyond The End Of The Century, Becoming An Amplifying Driver Of Mass Loss As The Ice Sheet'S Surface Mass Balance Decreases. We Show That This Transition Occurs When Antarctic Near-Surface Warming Exceeds A Critical Threshold Of +7.5 Circle C, At Which The Increase In Surface Runoff Outweighs The Increase In Snow Accumulation, A Signal That Is Amplified By The Melt-Elevation Feedback. Therefore, Under The Very High-Emission Scenario, Oceanic And Atmospheric Drivers Are Projected To Result In A Complete Collapse Of The West Antarctic Ice Sheet Along With Significant Grounding-Line Retreat In The Marine Basins Of The East Antarctic Ice Sheet, Leading To A Median Global Mean Sea-Level Rise Of 2.75 (6.95) M By 2300 (3000). Under A More Sustainable Socio-Economic Pathway, We Find That The Antarctic Ice Sheet May Still Contribute To A Median Global Mean Sea-Level Rise Of 0.62 (1.85) M By 2300 (3000). However, The Rate Of Sea-Level Rise Is Significantly Reduced As Mass Loss Is Likely To Remain Confined To The Amundsen Sea Embayment, Where Present-Day Climate Conditions Seem Sufficient To Commit To A Continuous Retreat Of Thwaites Glacier.
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Courtial-Manent, L., Ravanel, L., Mugnier, J., Deline, P., Lhosmot, A., Rabatel, A., et al. (2024). 18-Years Of High-Alpine Rock Wall Monitoring Using Terrestrial Laser Scanning At The Tour Ronde East Face, Mont-Blanc Massif. Environmental Research Letters, 191(3).
Abstract: Since The End Of The 20Th Century, Each Decade Has Been Warmer Than The Previous One In The European Alps. As A Consequence, Alpine Rock Walls Are Generally Facing High Rockfall Activity, Likely Due To Permafrost Degradation. We Use A Unique Terrestrial Laser Scanning Derived Rockfall Catalog Over 18 Years (2005-2022) Compared With Photographs (1859-2022) To Quantify The Evolution Of The East Face Of Tour Ronde (3440-3792 M A.S.L.) In The Mont-Blanc Massif (Western European Alps) That Is Permafrost-Affected. Overall, 210 Rockfalls Were Identified, From 1 To 15 500 M(3). Forty-Five Events Were >100 M(3) While Cumulated Volume Of Events <10 M(3) Represents <1% Of The Fallen Rocks. The Rockfall Magnitude-Frequency Distribution Of The Overall Inventory Follows A Power Law, With A Mean Exponent B Of 0.44 +/- 0.03, Characterizing A High Contribution Of Large Rockfalls. The Depth Of Failure Ranges From A Few Centimeters To More Than 20 M While 95% Of The Rockfalls Depth Is <5 M, Highlighting The Role Of The Active Layer. The Mean Rock Wall Erosion Rate Is 18.3 +/- 0.2 Mm Yr(-1) For The 2005-2022 Period And Ranks In The Top Range Of Reported Values In The Alps. It Has Greatly Increased Between The Periods 2006-2014 And 2016-2022, Probably In Relation To A Series Of Summer Heat Waves. The Exceptional Erosion Rate Of 2015 Is Driven By One Large Rockfall In August. Since 2006, An Ice Apron That Covered 16 100 M(2) Has Now Almost Vanished, And The Surface Of The Glacier Du G & Eacute;Ant At The Rock Wall Foot Has Lowered By Several Tens Of Meters. The Retreat Of These Two Ice Masses Contributed To The Rock Wall Instability As More Than 35% Of The Rockfall Volume Detached From The Deglaciated Surfaces.
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Delhasse, A., Beckmann, J., Kittel, C., & Fettweis, X. (2024). Coupling Mar (Modèle Atmosphérique Régional) With Pism (Parallel Ice Sheet Model) Mitigates The Positive Melt-Elevation Feedback. Cryosphere, 181(2), 633–651.
Abstract: The Greenland Ice Sheet Is A Key Contributor To Sea Level Rise. By Melting, The Ice Sheet Thins, Inducing Higher Surface Melt Due To Lower Surface Elevations, Accelerating The Melt Coming From Global Warming. This Process Is Called The Melt-Elevation Feedback And Can Be Considered By Using Two Types Of Models: Either (1) Atmospheric Models, Which Can Represent The Surface Mass Balance (Smb), Or Smb Estimates Resulting From Simpler Models Such As Positive Degree Day Models Or (2) Ice Sheet Models Representing The Surface Elevation Evolution. The Latter Ones Do Not Represent The Surface Mass Balance Explicitly As Well As Polar-Oriented Climate Models. A New Coupling Between The Mar (Modele Atmospherique Regional) Regional Climate Model And The Pism (Parallel Ice Sheet Model) Ice Sheet Model Is Presented Here Following The Cesm2 (Community Earth System Model; Ssp5-8.5, Shared Socioeconomic Pathway) Scenario Until 2100 At The Mar Lateral Boundaries. The Coupling Is Extended To 2200 With A Stabilised Climate (+7 Circle C Compared To 1961-1990) By Randomly Sampling The Last 10 Years Of Cesm2 To Force Mar And Reaches A Sea Level Rise Contribution Of 64 Cm. The Fully Coupled Simulation Is Compared To A One-Way Experiment Where Surface Topography Remains Fixed In Mar. However, The Surface Mass Balance Is Corrected For The Melt-Elevation Feedback When Interpolated On The Pism Grid By Using Surface Mass Balance Vertical Gradients As A Function Of Local Elevation Variations (Offline Correction). This Method Is Often Used To Represent The Melt-Elevation Feedback And Prevents A Coupling Which Is Too Expensive In Computation Time. In The Fully Coupled Mar Simulation, The Ice Sheet Morphology Evolution (Changing Slope And Reducing The Orographic Barrier) Induces Changes In Local Atmospheric Patterns. More Specifically, Wind Regimes Are Modified, As Well As Temperature Lapse Rates, Influencing The Melt Rate Through Modification Of Sensible Heat Fluxes At The Ice Sheet Margins. We Highlight Mitigation Of The Melt Lapse Rate On The Margins By Modifying The Surface Morphology. The Lapse Rates Considered By The Offline Correction Are No Longer Valid At The Ice Sheet Margins. If Used (One-Way Simulation), This Correction Implies An Overestimation Of The Sea Level Rise Contribution Of 2.5 %. The Mitigation Of The Melt Lapse Rate On The Margins Can Only Be Corrected By Using A Full Coupling Between An Ice Sheet Model And An Atmospheric Model.
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Diedhiou, C., Panthou, G., Diatta, S., Sané, Y., Vischel, T., & Camara, M. (2024). Simple Scaling Of Extreme Precipitation Regime In Senegal. Scientific African, 232.
Abstract: Extreme Precipitation Exhibits High Temporal And Spatial Variability, And Understanding This Variability Is Crucial For Designing Hydraulic Infrastructures And Assessing The Impacts Of Natural Risks Such As Floods And Droughts. The Simple Scaling (Ss) Model, Which Describes The Dependence Of Extreme Rainfall Statistics On Timescales, Is Used To Estimate Intensity Duration Frequency (Idf) Curves. This Study Aims To Evaluate The Validity Of The Simple Scaling (Ss) Hypothesis For 14 Rain Gauges In Senegal And Explore The Existence Of Breaks In Temporal Scaling Regimes (Transition Regimes). For The Analysis Of Extreme Characteristics, We Considered The Annual Maximum Series (Ams) Of Precipitation In Sub-Hourly And Supra-Daily Durations Ranging From 10 Min To 7 Days. The Empirical Validation Of The Ss Models Was Confirmed For The Majority Of The Scaling Intervals. We Identified Two Scaling Breaks, Indicating The Presence Of Three Scaling Regimes: Short Durations (Sd), Intermediate Durations (Id), And Long Durations (Ld). The Spatial Variation Of Scaling Exponents Reveals The Existence Of Different Scaling Regimes Across Senegal. The Results Are Valuable For Modeling The Spatial Distribution Of Scaling Exponents, Which Can Aid In Characterizing Idf Curves At Ungauged Locations.
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Evin, G., Le Lay, M., Fouchier, C., Penot, D., Colleoni, F., Mas, A., et al. (2024). Evaluation Of Hydrological Models On Small Mountainous Catchments: Impact Of The Meteorological Forcings. Hydrology And Earth System Sciences, 282(1), 261–281.
Abstract: Hydrological Modelling Of Small Mountainous Catchments Is Particularly Challenging Because Of The High Spatio-Temporal Resolution Required For The Meteorological Forcings. In Situ Measurements Of Precipitation Are Typically Scarce In These Remote Areas, Particularly At High Elevations. Precipitation Reanalyses Propose Different Alternative Forcings For The Simulation Of Streamflow Using Hydrological Models. In This Paper, We Evaluate The Performances Of Two Hydrological Models Representing Some Of The Key Processes For Small Mountainous Catchments ( < 300 Km( 2) ), Using Different Meteorological Products With A Fine Spatial And Temporal Resolution. The Evaluation Is Performed On 55 Small Catchments Of The Northern French Alps. While The Simulated Streamflows Are Adequately Reproduced For Most Of The Configurations, These Evaluations Emphasize The Added Value Of Radar Measurements, In Particular For The Reproduction Of Flood Events. However, These Better Performances Are Only Obtained Because The Hydrological Models Correct The Underestimations Of Accumulated Amounts (E.G. Annual) From The Radar Data In High-Elevation Areas.
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Flamant, C., Chaboureau, J., Delanoë, J., Gaetani, M., Jamet, C., Lavaysse, C., et al. (2024). Cyclogenesis In The Tropical Atlantic First Scientific Highlights From The Clouds-Atmospheric Dynamics-Dust Interactions In West Africa (Caddiwa) Field Campaign. Bulletin Of The American Meteorological Society, 1051(2), E387–E417.
Abstract: During The Boreal Summer, Mesoscale Convective Systems Generated Over West Africa Propagate Westward And Interact With African Easterly Waves, And Dust Plumes Transported From The Sahel And Sahara By The African Easterly Jet. Once Off West Africa, The Vortices In The Wake Of These Mesoscale Convective Systems Evolve In A Complex Environment Sometimes Leading To The Development Of Tropical Storms And Hurricanes, Especially In September When Sea Surface Temperatures Are High. Numerical Weather Predictions Of Cyclogenesis Downstream Of West Africa Remains A Key Challenge Due To The Incomplete Understanding Of The Clouds-Atmospheric Dynamics-Dust Interactions That Limit Predictability. The Primary Objective Of The Clouds-Atmospheric Dynamics-Dust Interactions In West Africa (Caddiwa) Project Is To Improve Our Understanding Of The Relative Contributions Of The Direct, Semidirect, And Indirect Radiative Effects Of Dust On The Dynamics Of Tropical Waves As Well As The Intensification Of Vortices In The Wake Of Offshore Mesoscale Convective Systems And Their Evolution Into Tropical Storms Over The North Atlantic. Airborne Observations Relevant To The Assessment Of Such Interactions (Active Remote Sensing, In Situ Microphysics Probes, Among Others) Were Made From 8 To 21 September 2021 In The Tropical Environment Of Sal Island, Cape Verde. The Environments Of Several Tropical Cyclones, Including Tropical Storm Rose, Were Monitored And Probed. The Airborne Measurements Also Serve The Purpose Of Regional Model Evaluation And The Validation Of Spaceborne Wind, Aerosol And Cloud Products Pertaining To Satellite Missions Of The European Space Agency And Eumetsat (Including The Aeolus, Earthcare, And Iasi Missions).
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Fourteau, K., Brondex, J., Brun, F., & Dumont, M. (2024). A Novel Numerical Implementation For The Surface Energy Budget Of Melting Snowpacks And Glaciers. Geoscientific Model Development, 171(4), 1903–1929.
Abstract: The Surface Energy Budget Drives The Melt Of The Snow Cover And Glacier Ice And Its Computation Is Thus Of Crucial Importance In Numerical Models. This Surface Energy Budget Is The Result Of Various Surface Energy Fluxes, Which Depend On The Input Meteorological Variables And Surface Temperature; Of Heat Conduction Towards The Interior Of The Snow/Ice; And Potentially Of Surface Melting If The Melt Temperature Is Reached. The Surface Temperature And Melt Rate Of A Snowpack Or Ice Are Thus Driven By Coupled Processes. In Addition, These Energy Fluxes Are Non-Linear With Respect To The Surface Temperature, Making Their Numerical Treatment Challenging. To Handle This Complexity, Some Of The Current Numerical Models Tend To Rely On A Sequential Treatment Of The Involved Physical Processes, In Which Surface Fluxes, Heat Conduction, And Melting Are Treated With Some Degree Of Decoupling. Similarly, Some Models Do Not Explicitly Define A Surface Temperature And Rather Use The Temperature Of The Internal Point Closest To The Surface Instead. While These Kinds Of Approaches Simplify The Implementation And Increase The Modularity Of Models, They Can Also Introduce Several Problems, Such As Instabilities And Mesh Sensitivity. Here, We Present A Numerical Methodology To Treat The Surface And Internal Energy Budgets Of Snowpacks And Glaciers In A Tightly Coupled Manner, Including Potential Surface Melting When The Melt Temperature Is Reached. Specific Care Is Provided To Ensure That The Proposed Numerical Scheme Is As Fast And Robust As Classical Numerical Treatment Of The Surface Energy Budget. Comparisons Based On Simple Test Cases Show That The Proposed Methodology Yields Smaller Errors For Almost All Time Steps And Mesh Sizes Considered And Does Not Suffer From Numerical Instabilities, Contrary To Some Classical Treatments.
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Fugger, S., Shaw, T., Jouberton, A., Miles, E., Buri, P., Mccarthy, M., et al. (2024). Hydrological Regimes And Evaporative Flux Partitioning At The Climatic Ends Of High Mountain Asia. Environmental Research Letters, 191(4).
Abstract: High Elevation Headwater Catchments Are Complex Hydrological Systems That Seasonally Buffer Water And Release It In The Form Of Snow And Ice Melt, Modulating Downstream Runoff Regimes And Water Availability. In High Mountain Asia (Hma), Where A Wide Range Of Climates From Semi-Arid To Monsoonal Exist, The Importance Of The Cryospheric Contributions To The Water Budget Varies With The Amount And Seasonal Distribution Of Precipitation. Losses Due To Evapotranspiration And Sublimation Are To Date Largely Unquantified Components Of The Water Budget In Such Catchments, Although They Can Be Comparable In Magnitude To Glacier Melt Contributions To Streamflow. Here, We Simulate The Hydrology Of Three High Elevation Headwater Catchments In Distinct Climates In Hma Over 10 Years Using An Ecohydrological Model Geared Towards High-Mountain Areas Including Snow And Glaciers, Forced With Reanalysis Data. Our Results Show That Evapotranspiration And Sublimation Together Are Most Important At The Semi-Arid Site, Kyzylsu, On The Northernmost Slopes Of The Pamir Mountain Range. Here, The Evaporative Loss Amounts To 28% Of The Water Throughput, Which We Define As The Total Water Added To, Or Removed From The Water Balance Within A Year. In Comparison, Evaporative Losses Are 19% At The Central Himalayan Site Langtang And 13% At The Wettest Site, 24 K, On The Southeastern Tibetan Plateau. At The Three Sites, Respectively, Sublimation Removes 15%, 13% And 6% Of Snowfall, While Evapotranspiration Removes The Equivalent Of 76%, 28% And 19% Of Rainfall. In Absolute Terms, And Across A Comparable Elevation Range, The Highest Et Flux Is 413 Mm Yr-1 At 24 K, While The Highest Sublimation Flux Is 91 Mm Yr-1 At Kyzylsu. During Warm And Dry Years, Glacier Melt Was Found To Only Partially Compensate For The Annual Supply Deficit.
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Fürst, J., Farías-Barahona, D., Blindow, N., Casassa, G., Gacitúa, G., Koppes, M., et al. (2024). The Foundations Of The Patagonian Icefields. Communications Earth & Environment, 5(1).
Abstract: The Two Vast Patagonian Icefields Are A Global Hotspot For Ice-Loss. However, Not Much Is Known About The Total Ice Volume They Store – Let Alone Its Spatial Distribution. One Reason Is That The Abundant Record Of Direct Thickness Measurements Has Never Been Systematically Exploited. Here, This Record Is Combined With Remotely-Sensed Information On Past Ice Thickness Mapped From Glacier Retreat. Both Datasets Are Incorporated In A State-Of-The-Art, Mass-Conservation Approach To Produce A Well-Informed Map Of The Basal Topography Beneath The Icefields. Its Major Asset Is The Reliability Increase Of Thicknesses Values Along The Many Marine- And Lake-Terminating Glaciers. For These, Frontal Ice-Discharge Is Notably Lower Than Previously Reported. This Finding Implies That Direct Climatic Control Was More Influential For Past Ice Loss. We Redact A Total Volume For Both Icefields In 2000 Of 5351 Km3. Despite The Wealth Of Observations Used In This Assessment, Relative Volume Uncertainties Remain Elevated. The Southern Patagonian Icefield Likely Stores Around 10% More Ice Than Previously Believed, According To Ice Thickness Estimates Based On Remote Sensing And Direct Measurement-Informed Mapping Of The Sub-Glacial Topography.
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Gao, Q., Sime, L., Mclaren, A., Bracegirdle, T., Capron, E., Rhodes, R., et al. (2024). Evaporative Controls On Antarctic Precipitation: An Echam6 Model Study Using Innovative Water Tracer Diagnostics. Cryosphere, 181(2), 683–703.
Abstract: Improving Our Understanding Of The Controls On Antarctic Precipitation Is Critical For Gaining Insights Into Past And Future Polar And Global Environmental Changes. Here We Develop Innovative Water Tracing Diagnostics In The Atmospheric General Circulation Model Echam6. These Tracers Provide New Detailed Information On Moisture Source Locations And Properties Of Antarctic Precipitation. In The Preindustrial Simulation, Annual Mean Antarctic Precipitation Originating From The Open Ocean Has A Source Latitude Range Of 49-35 Circle S, A Source Sea Surface Temperature Range Of 9.8-16.3 Circle C, A Source 2 M Relative Humidity Range Of 75.6 %-83.3 %, And A Source 10 M Wind Velocity (Vel10) Range Of 10.1 To 11.3 Ms-1. These Results Are Consistent With Estimates From Existing Literature. Central Antarctic Precipitation Is Sourced From More Equatorward (Distant) Sources Via Elevated Transport Pathways Compared To Coastal Antarctic Precipitation. This Has Been Attributed To A Moist Isentropic Framework; I.E. Poleward Vapour Transport Tends To Follow Constant Equivalent Potential Temperature. However, We Find Notable Deviations From This Tendency Especially In The Lower Troposphere, Likely Due To Radiative Cooling. Heavy Precipitation Is Sourced By Longer-Range Moisture Transport: It Comes From 2.9 Circle (300 Km, Averaged Over Antarctica) More Equatorward (Distant) Sources Compared To The Rest Of Precipitation. Precipitation During Negative Phases Of The Southern Annular Mode (Sam) Also Comes From More Equatorward Moisture Sources (By 2.4 Circle, Averaged Over Antarctica) Compared To Precipitation During Positive Sam Phases, Likely Due To Amplified Planetary Waves During Negative Sam Phases. Moreover, Source Vel10 Of Annual Mean Precipitation Is On Average 2.1 Ms-1 Higher Than Annual Mean Vel10 At Moisture Source Locations From Which The Precipitation Originates. This Shows That The Evaporation Of Moisture Driving Antarctic Precipitation Occurs Under Windier Conditions Than Average. We Quantified This Dynamic Control Of Southern Ocean Surface Wind On Moisture Availability For Antarctic Precipitation. Overall, The Innovative Water Tracing Diagnostics Enhance Our Understanding Of The Controlling Factors Of Antarctic Precipitation.
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Guerrieri, A., Cantera, I., Marta, S., Bonin, A., Carteron, A., Ambrosini, R., et al. (2024). Local Climate Modulates The Development Of Soil Nematode Communities After Glacier Retreat. Global Change Biology, 303(1).
Abstract: The Worldwide Retreat Of Glaciers Is Causing A Faster Than Ever Increase In Ice-Free Areas That Are Leading To The Emergence Of New Ecosystems. Understanding The Dynamics Of These Environments Is Critical To Predicting The Consequences Of Climate Change On Mountains And At High Latitudes. Climatic Differences Between Regions Of The World Could Modulate The Emergence Of Biodiversity And Functionality After Glacier Retreat, Yet Global Tests Of This Hypothesis Are Lacking. Nematodes Are The Most Abundant Soil Animals, With Keystone Roles In Ecosystem Functioning, But The Lack Of Global-Scale Studies Limits Our Understanding Of How The Taxonomic And Functional Diversity Of Nematodes Changes During The Colonization Of Proglacial Landscapes. We Used Environmental Dna Metabarcoding To Characterize Nematode Communities Of 48 Glacier Forelands From Five Continents. We Assessed How Different Facets Of Biodiversity Change With The Age Of Deglaciated Terrains And Tested The Hypothesis That Colonization Patterns Are Different Across Forelands With Different Climatic Conditions. Nematodes Colonized Ice-Free Areas Almost Immediately. Both Taxonomic And Functional Richness Quickly Increased Over Time, But The Increase In Nematode Diversity Was Modulated By Climate, So That Colonization Started Earlier In Forelands With Mild Summer Temperatures. Colder Forelands Initially Hosted Poor Communities, But The Colonization Rate Then Accelerated, Eventually Leveling Biodiversity Differences Between Climatic Regimes In The Long Term. Immediately After Glacier Retreat, Communities Were Dominated By Colonizer Taxa With Short Generation Time And R-Ecological Strategy But Community Composition Shifted Through Time, With Increased Frequency Of More Persister Taxa With K-Ecological Strategy. These Changes Mostly Occurred Through The Addition Of New Traits Instead Of Their Replacement During Succession. The Effects Of Local Climate On Nematode Colonization Led To Heterogeneous But Predictable Patterns Around The World That Likely Affect Soil Communities And Overall Ecosystem Development.
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Guillemot, A., Bontemps, N., Larose, E., Teodor, D., Faller, S., Baillet, L., et al. (2024). Investigating Subglacial Water-Filled Cavities By Spectral Analysis Of Ambient Seismic Noise: Results On The Polythermal Tête-Rousse Glacier (Mont Blanc, France). Geophysical Research Letters, 515(4).
Abstract: Polythermal Glaciers Can Trap Considerable Volumes Of Liquid Water With The Potential To Generate Devastating Outburst Floods. This Study Aims To Identify Water-Filled Subglacial Reservoirs From Ambient Seismic Noise Collected By Moderate-Cost Surveys. The Horizontal-To-Vertical Spectral Ratio Technique Is Highly Sensitive To Impedance Contrasts At Interfaces, Thus Commonly Used To Estimate Glacier Thickness. Here, We Focus On The Inverse Ratio, That Is, The V/H Spectral Ratio (Vhsr), Whose High Values Indicate A Low Impedance Volume Beneath The Surface, Suggesting Subglacial Cavities. We Analyze Vhsr Peaks From A Seismic Array Of 60 Nodes Installed On The Tete-Rousse Glacier (Mont Blanc Massif, French Alps); Data Were Gathered Over 15 Days. Mapping The Vhsr Amplitude Over The Free Surface Reveals The Main Cavity Locations And The Basal Areas Affected By Melting Within The Glacier. Results Obtained In The Field Are Supported By A Conceptual Model Based On 3D Finite-Element Simulations. Considerable Volumes Of Liquid Water May Be Trapped Within Cavities In Polythermal Glaciers. If These Cavities Rupture, The Resulting Outburst Flood Has The Potential To Cause Devastation In Populated Mountain Areas. With The Aim Of Testing Methods To Locate Such Cavities, We Installed 60 Small 3-Component Seismic Sensors On The Tete-Rousse Glacier (Mont Blanc Massif, French Alps), Which Is Known To Contain Such Cavities. We Used These Sensors To Test A Detection Method Based On Ambient Seismic Noise. For 3 Weeks, The Sensors Recorded Vibrations Within The Glacier. On A Glacier Without Cavities, These Vibrations Ought To Be Predominantly In The Horizontal Direction. In The Presence Of A Cavity, We Expect The Ice Above The Cavity To Vibrate Mostly Vertically-Like A Bridge. In This Paper, We Highlight Areas On The Glacier Where Vertical Vibrations Were Stronger Than Horizontal Vibrations. These Areas Fit Well With The Locations Of The Main Known Cavities In This Glacier, And With Areas Affected By Basal Melting. We Supported Our Field Observations With Modeling Based On 3D Simulations, Paving The Way To A New Method To Locate Water-Filled Cavities Within Glaciers. Spectral Analysis From Ambient Seismic Noise Is Complementary To Other Geophysical Methods For Investigating Glaciers At Depth Results Suggest That The Vertical-To-Horizontal Spectral Ratio Is A Reliable Proxy To Locate Subglacial Cavities Experimental Results Were Confirmed Using A Simplified Numerical Model
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Gustin, M., Dunham-Cheatham, S., Osterwalder, S., Magand, O., & Dommergue, A. (2024). What Is The Utility Of Measuring Gaseous Hgii Dry Deposition Using Aerohead Samplers?: A Review. Science Of The Total Environment, 9079.
Abstract: The Most Efficient Way To Quantify Hgii Inputs To Ecosystems Is To Measure Wet And Dry Deposition. Wet Deposition Of Hgii Is Determined By Measuring Hg Concentrations And The Volume Of Precipitation. Dry Deposition Of Hgii Is Determined Through Direct Measurement And/Or Determined Indirectly By Measuring Air Concentrations And Using Model-Generated Deposition Velocities. Here, Data Collected Using An Aerohead Sampler Holding Cation Exchange Membranes Are Summarized, And The Utility Of This Method For Understanding Dry Deposition, And Other Measurements And Processes Is Discussed. This Analysis Includes Information From Publications, And Recent Data Collected At Guadalupe Mountains National Park, Texas, Usa, And Amsterdam Island, Southern Indian Ocean. This Method Primarily Measures Gaseous Hgii And Little Particulate-Bound Hg. The Aerohead Method Is Useful For Looking At Large-Scale Trends In Deposition, Verifying Hg Depletion Events, Calculating Dry Deposition Velocities For Compounds With Specific Chemistry, And Identification Of Sources Of Hgii. At Numerous Locations In The Western Usa, Deposition Rates Were Greater At Higher Elevations Due To Elevated Concentrations Associated With Longrange Transport Of Atmospheric Pollution. When Used In Tandem With The Reactive Mercury Active System Or A Dual-Channel System, More Accurate Deposition Velocities – That Vary As A Function Of Gom Compound Chemistry – Can Be Calculated.
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Hachgenei, N., Robinet, N., Baduel, C., Nord, G., Spadini, L., Martins, J., et al. (2024). Catchment-Scale Rapid Transfer Of Livestock Pharmaceuticals Under Mediterranean Climate. Science Of The Total Environment, 9069.
Abstract: Various Pharmaceuticals Are Essential For Livestock Farming, But Some Are Highly Toxic To Aquatic Life If They Reach Surface Water Bodies. Mediterranean Climate Is Characterized By Dry Summers Followed By Intense Autumn Storms. We Studied The Effect Of These Climatic Conditions On The Risk Of Pharmaceutical Residues Transfer To Streams At The Catchment-Scale. Pharmaceutical Products Routinely Used In The Study Area, As Well As Their Application Frequency And Season, Were Identified Through Interviews With Farmers. As A Proof A Concept, Three Veterinary Pharmaceuticals (Fenbendazole (Fbz), Mebendazole (Mbz) And Ivermectin (Ivm)) Were Chosen As Model Chemicals Based On Their Relatively High Usage, Their Specificity To Represent Different Types Of Livestock (Swine, Sheep And Cattle), And Their Ability To Be Analyzed Using The Same Analytical Method. Stream Water Was Analyzed During Low Flow Periods And At High Frequency (Up To 2 H(-1)) During Flood Events. The Selected Veterinary Pharmaceuticals Were Not Detected During Low Flow, But Fbz And Mbz Reached High Concentrations For Short Periods During Floods. Due To The Event-Driven Nature Of Their Transfer, A Significant Load Of Veterinary Pharmaceuticals Can Reach The River And Cause Temporary But Significant Degradation Of Water Quality (E.G. For Fbz, The Water Concentration Reached Up To 355 Times The Predicted No Effect Concentration (Pnec)). This Indicates That Special Care Should Be Taken To Avoid Keeping Freshly Treated Livestock On Pastures That May Become Hydrologically Connected Under Wet Conditions. In Addition, It Suggests That Low-Frequency Monitoring Is Not Sufficient To Detect Those High Concentration Levels That Exist During Very Short Periods.
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Haruna, A., Blanchet, J., & Favre, A. (2024). Estimation Of Intensity-Duration-Area-Frequency Relationships Based On The Full Range Of Non-Zero Precipitation From Radar-Reanalysis Data. Water Resources Research, 606(2).
Abstract: Intensity-Duration-Area-Frequency (Idaf) Models Provide The Mathematical Link Between Precipitation Intensities (I), Durations (D), Areas (A), And Frequency Of Occurrence (F). They Play A Critical Role In Hydrological Design, Areal Rainfall Hazard Quantification, Storm Characterization, And Early Warning System Development. Idaf Models Extend The Conventional Intensity-Duration-Frequency Models By Accounting For The Spatial Extent Of Precipitation (I.E., The Area). In This Study, We Develop Idaf Models Using The Entire Non-Zero Precipitation Intensities, Not Only The Extremes. We Use The Extended Generalized Pareto Distribution (Egpd) To Model The Precipitation Intensities. To Build The Idaf Models, We Adopt A Data-Driven Approach That Allows The Linkage Of Egpd Parameters With Duration And Area, Based On Empirically Determined Parametric Relationships. The Inference Of Model Parameters Is Done Using A Global Maximum Likelihood Estimation, And Uncertainties Are Assessed By The Bootstrap Method. The Study Area Is Switzerland, A Topographically Complex Region Of 42,000 Km2 With Regional Precipitation Variability And Clear Seasonality. The Study Utilizes 17 Years Of Data From Combiprecip, A Radar-Reanalysis Product Developed By Geostatistically Merging Radar And Rain Gauge Data In An Operational Setting. We Build The Idaf Models For The Spatiotemporal Range Of 1-72 Hr And 1 To 1,089 Km2 At Each Pixel In The Study Area. To The Best Of Our Knowledge, Our Study Is The First Attempt To Use The Egpd In Idaf Curve Modeling. It Discusses The Use And Limitations Of Combiprecip In Extreme Value Analysis And Highlights The Challenges Of Modeling Areal Precipitation In A Complex Topographical Environment. We Develop Seasonal Intensity Duration Area Frequency Models At Every Pixel Location In Switzerland We Use All The Non-Zero Precipitation Data And Model The Intensities Using The Extended Generalized Pareto Distribution We Highlight The Complexity Of Modeling Areal Precipitation In Mountainous Regions
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Jager, E., Gillet-Chaulet, F., Mouginot, J., & Millan, R. (2024). Validating Ensemble Historical Simulations Of Upernavik Isstrøm (1985-2019) Using Observations Of Surface Velocity And Elevation. Journal Of Glaciology, .
Abstract: The Future Of Tidewater Glaciers In Response To Climate Warming Is One Of The Largest Sources Of Uncertainty In The Contribution Of The Greenland Ice Sheet To Global Sea-Level Rise. In This Study, We Investigate The Ability Of An Ice-Sheet Model To Reproduce The Past Evolution Of The Velocity And Surface Elevation Of A Tidewater Glacier, Upernavik Isstrom, By Prescribing Front Positions. To Achieve This, We Run Two Ensembles Of Simulations With A Weertman And A Regularised-Coulomb Friction Law. We Show That The Ice-Flow Model Has To Include A Reduction In Friction In The First 15 Km Upstream Of The Ice Front In Fast-Flowing Regions To Capture The Trends Observed During The 1985-2019 Period. Without This Process, The Ensemble Model Overestimates The Ice Flow Before The Retreat Of The Front In 2005 And Does Not Fully Reproduce Its Acceleration During The Retreat. This Results In An Overestimation Of The Total Mass Loss Between 1985 And 2019 Of 50% (300 Vs 200 Gt). Using A Variance-Based Sensitivity Analysis, We Show That Uncertainties In The Friction Law And The Ice-Flow Law Have A Greater Impact On The Model Results Than Surface Mass Balance And Initial Surface Elevation.
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Jonville, T., Flamant, C., & Lavaysse, C. (2024). Dynamical Study Of Three African Easterly Waves In September 2021. Quarterly Journal Of The Royal Meteorological Society, .
Abstract: Three Convectively Active African Easterly Waves (Aews) That Propagated South Of The African Easterly Jet Were Observed Over The Northeast Atlantic Ocean In September 2021. Their Evolution Is Studied Using A Suite Of Theoretical Frameworks, As Well As The European Centre For Medium-Range Weather Forecast Reanalyses And Satellite-Derived Brightness Temperature Observations. The Environment Of These Aews Was Sampled During The Cloud-Atmospheric Dynamics-Dust Interactions In West Africa Campaign Near Cape Verde With The Goal To Assess Their Potential For Developing Into Tropical Cyclones. We Highlight The Processes That Inhibited The Development Of The First Aew (Which Evolved Into Tropical Disturbance Pierre-Henri) And That Played A Role In The Development Of The Later Two Into Tropical Storms Rose And Peter On September 19, 2021. The Three Aews Developed A So-Called “Marsupial Protective” Pouch. For Peter And Rose, The Pouch Was Associated With A Vertically Aligned Vortex At Low Levels And Efficiently Protected The Convective Systems Inside From Dry And Dusty Air Intrusion. The Development Of This Low-Level Vortex Is Associated With An Interaction With The Monsoon Trough For Rose And With A Vorticity Center Associated With A Wave Propagating North Of The African Easterly Jet (Aej) In The Case Of Peter. The Presence Of A Dust Flux Toward The Convective Core Near The Surface Is Highlighted For Rose And Peter In Spite Of The Presence Of The Protective Marsupial Pouch. On The Other Hand, Pierre-Henri Interacted Positively With Both The Monsoon Trough And An Aew North Of The Aej But Failed To Develop Into A Tropical Cyclone. The Wave North Of The Aej Brought Saharan Air Layer Air Masses Inside The Pouch That Led To A Drying Of The Circulation That May Explain The Decrease In Convective Activity. We Used Different Methods To Analyse The Processes That Helped Or Inhibited The Development Of Three African Easterly Waves (Aews) Into Tropical Cyclones. A Wave Pouch Structure That Protects A Convective System Moving With The Wave Is Observed In The Three Cases And Studied Within The Marsupial Paradigm Framework. The Development Of An Aligned Vortex At Low Levels, Either By Interaction With The Monsoon Trough Or Between Aews North And South Of The African Easterly Jet, Are Highlighted. In One Case, The Latter Interaction Caused The Intrusion Of Dry Air That Might Have Inhibited Cyclogenesis. Image
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Jurasz, J., Guezgouz, M., Campana, P., Kazmierezak, B., Kuriqi, A., Bloomfield, H., et al. (2024). Complementarity Of Wind And Solar Power In North Africa: Potential For Alleviating Energy Droughts And Impacts Of The North Atlantic Oscillation. Renewable & Sustainable Energy Reviews, 1911.
Abstract: With Growing Gas And Oil Prices, Electricity Generation Based On These Fossil Fuels Is Becoming Increasingly Expensive. Furthermore, The Vision Of Natural Gas As A Transition Fuel Is Subject To Many Constraints And Uncertainties Of Economic, Environmental, And Geopolitical Nature. Consequently, Renewable Energies Such As Solar And Wind Power Are Expected To Reach New Records Of Installed Capacity Over The Upcoming Years. Considering The Above, North Africa Is One Of The Regions With The Largest Renewable Resource Potential Globally. While Extensively Studied In The Literature, These Resources Remain Underutilized. Thus, To Contribute To Their Future Successful Deployment And Integration With The Power System, This Study Presents A Spatial And Temporal Analysis Of The Nature Of Solar And Wind Resources Over North Africa From The Perspective Of Energy Droughts. Both The Frequency And Maximal Duration Of Energy Droughts Are Addressed. Both Aspects Of Renewables' Variable Nature Have Been Evaluated In The North Atlantic Oscillation (Nao) Context. The Analysis Considers The Period Between 1960 And 2020 Based On Hourly Reanalysis Data (I.E., Near-Surface Shortwave Irradiation, Wind Speed, And Air Temperature) And The Hurrel Nao Index. The Findings Show An In-Phase Relationship Between Solar Power And Winter Nao Index, Particularly Over The Coastal Regions In Western North Africa And Opposite Patterns In Its Eastern Part. For Wind Energy, The Connection With Nao Has A More Zonal Pattern, With Negative Correlations In The North And Positive Correlations In The South. Solar Energy Droughts Dominate Northern Tunisia, Algeria, And Morocco, While Wind Energy Droughts Mainly Occur In The Atlas Mountains Range. On Average, Solar Energy Droughts Tend Not To Exceed 2-3 Consecutive Days, With The Longest Extending For Five Days. Wind Energy Droughts Can Be As Prolonged As 80 Days (Atlas Mountains). Hybridizing Solar And Wind Energy Reduces The Potential For Energy Droughts Significantly. At The Same Time, The Correlation Between Their Occurrence And The Nao Index Remains Low. These Findings Show The Potential For Substantial Resilience To Inter-Annual Climate Variability, Which Could Benefit The Future Stability Of Renewables-Dominated Power Systems.
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Katharina, K., Berg, P., Bozhinova, D., Crochemore, L., Du, Y., Pechlivanidis, I., et al. (2024). Robustness Of Hydrometeorological Extremes In Surrogated Seasonal Forecasts. International Journal Of Climatology, .
Abstract: Water And Disaster Risk Management Require Accurate Information About Hydrometeorological Extremes. However, Estimation Of Rare Events Using Extreme Value Analysis Is Hampered By Short Observational Records, With Large Resulting Uncertainties. Here, We Present A Surrogate World Setup That Makes Use Of Data Samples From Meteorological And Hydrological Seasonal Re-Forecasts To Explore Extremes For Long Return Periods. The Surrogate Timeseries Allow Us To Pool The Re-Forecasts Into 1000-Year-Long Timeseries. We Can Then Calculate Return Values Of Extremes And Explore How They Are Affected By The Size Of Sub-Samples As Method For Estimating The Uncertainty. The Approach Relies On The Fact That Probabilistic Seasonal Re-Forecasts, Initialized With Perturbed Initial Conditions, Have Limited Predictive Skill With Increasing Lead Time. At Long Lead Times Re-Forecasts Will Diverge Into Independent Samples. The Meteorological Seasonal Re-Forecasts Are Taken From The Seas5 System, And Hydrological Re-Forecasts Are Generated With The E-Hype Process-Based Model For The Pan-European Domain. Extreme Value Analysis Is Applied To Annual Maxima Of Precipitation And Streamflow For Return Periods Of 100 Years. The Analysis Clearly Demonstrates The Large Uncertainty In Long Return Period Estimates With Typical Available Samples Of Only Few Decades. The Uncertainty Is Somewhat Reduced For 100-Year Samples, But Several 100 Years Seem To Be Necessary To Have Robust Estimates. The Bootstrap With Replacement Approach Is Applied To Shorter Timeseries, And Is Shown To Well Reproduce The Uncertainty Range Of The Longer Samples. However, The Main Estimate Of The Return Value Can Be Significantly Offset. Although The Method Is Model Based, With The Associated Uncertainties And Bias Compared To The Real World, The Surrogate Approach Is Likely Useful To Explore Rare And Compounding Extremes. A Method To Generate 1000-Of-Years Long Surrogate Timeseries For Assessing Extreme Streamflow Using Seasonal Forecast Data Is Presented. Illustrative Cases Compare Conventional Bootstrap Method On Single Shorter Timeseries To The Surrogate Data, And Show A Rather Good Sampling Of The Uncertainty, But A Lack Of Precision For The Expected Value. Image
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Kellerer-Pirklbauer, A., Bodin, X., Delaloye, R., Lambiel, C., Gärtner-Roer, I., Bonnefoy-Demongeot, M., et al. (2024). Acceleration And Interannual Variability Of Creep Rates In Mountain Permafrost Landforms (Rock Glacier Velocities) In The European Alps In 1995-2022. Environmental Research Letters, 191(3).
Abstract: Cryospheric Long-Term Timeseries Get Increasingly Important. To Document Climate-Related Effects On Long-Term Viscous Creep Of Ice-Rich Mountain Permafrost, We Investigated Timeseries (1995-2022) Of Geodetically-Derived Rock Glacier Velocity (Rgv), I.E. Spatially Averaged Interannual Velocity Timeseries Related To A Rock Glacier (Rg) Unit Or Part Of It. We Considered 50 Rgv From 43 Rgs Spatially Covering The Entire European Alps. Eight Of These Rgs Are Destabilized. Results Show That Rgv Are Distinctly Variable Ranging From 0.04 To 6.23 M A-1. Acceleration And Deceleration At Many Rgs Are Highly Correlated With Similar Behaviour Over 2.5 Decades For 15 Timeseries. In Addition To A General Long-Term, Warming-Induced Trend Of Increasing Velocities, Three Main Phases Of Distinct Acceleration (2000-2004, 2008-2015, 2018-2020), Interrupted By Deceleration Or Steady State Conditions, Were Identified. The Evolution Is Attributed To Climate Forcing And Underlines The Significance Of Rgv As A Product Of The Essential Climate Variable (Ecv) Permafrost. We Show That Rgv Data Are Valuable As Climate Indicators, But Such Data Should Always Be Assessed Critically Considering Changing Local Factors (Geomorphic, Thermal, Hydrologic) And Monitoring Approaches. To Extract A Climate Signal, Larger Rgv Ensembles Should Be Analysed. Criteria For Selecting New Rgv-Sites Are Proposed.
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Lapere, R., Thomas, J., Favier, V., Angot, H., Asplund, J., Ekman, A., et al. (2024). Polar Aerosol Atmospheric Rivers: Detection, Characteristics, And Potential Applications. Journal Of Geophysical Research-Atmospheres, 1291(2).
Abstract: Aerosols Play A Key Role In Polar Climate, And Are Affected By Long-Range Transport From The Mid-Latitudes, Both In The Arctic And Antarctic. This Work Investigates Poleward Extreme Transport Events Of Aerosols, Referred To As Polar Aerosol Atmospheric Rivers (P-Aar), Leveraging The Concept Of Atmospheric Rivers (Ar) Which Signal Extreme Transport Of Moisture. Using Reanalysis Data, We Build A Detection Catalog Of P-Aars For Black Carbon, Dust, Sea Salt And Organic Carbon Aerosols, For The Period 1980-2022. First, We Describe The Detection Algorithm, Discuss Its Sensitivity, And Evaluate Its Validity. Then, We Present Several Extreme Transport Case Studies, In The Arctic And In The Antarctic, Illustrating The Complementarity Between Ars And P-Aars. Despite Similarities In Transport Pathways During Co-Occurring Ar/P-Aar Events, Vertical Profiles Differ Depending On The Species, And Large-Scale Transport Patterns Show That Moisture And Aerosols Do Not Necessarily Originate From The Same Areas. The Complementarity Between Ar And P-Aar Is Also Evidenced By Their Long-Term Characteristics In Terms Of Spatial Distribution, Seasonality And Trends. P-Aar Detection, As A Complement To Ar, Can Have Several Important Applications For Better Understanding Polar Climate And Its Connections To The Mid-Latitudes. The Extreme Transport Of Aerosol-Containing Air Masses, From The Mid-Latitudes To The Polar Regions, Can Be Characterized And Quantified By Leveraging Polar Aerosol Atmospheric Rivers (P-Aars). This Is Similar To The Atmospheric Rivers (Ars) Which Carry Large Amounts Of Water To The Poles And Affect The Overall Stability Of Polar Ecosystems. In This Work, We Establish A Detection Algorithm For P-Aars And Evaluate It For Different Well-Known Aerosol Intrusions Or Ar Events. The Areas Most Affected By P-Aars Are Described, Their Trends Are Investigated And We Discuss The Potential Applications Of P-Aar Detection For A Better Understanding Of Polar Climate. A Catalog Of Polar Aerosol Atmospheric Rivers (P-Aar) Is Provided For 1980-2022 By Adapting An Atmospheric River (Ar) Detection Schemeimportant P-Aar Events, Representing Rapid Poleward Transport Of Aerosol-Enriched Air Masses, Are Presentedcombining Ar And P-Aar Can Improve Our Understanding Of The Links Between Mid- And Polar-Latitudes, In The Past, Present And Future Climate
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Legrand, M., Preunkert, S., Kutuzov, S., Siour, G., Mikhalenko, V., Dolgova, E., et al. (2024). 20Th Century Changes Of Doc And Its <Sup>14</Sup>C Signature Archived In Caucasus Ice-Core: Implications For Past Sources Of Organic Carbon Aerosol In South-Eastern Europe. Journal Of Geophysical Research-Atmospheres, 1291(5).
Abstract: To Reconstruct The History Of Organic Carbon (Oc) Aerosol Over South-Eastern Europe, Dissolved Organic Carbon (Doc) And Its C-14 Signature ((Doc)-C-14) Were Investigated Along An Ice Core Drilled At The Mount Elbrus (Elb) In Caucasus. In Summer, Compared To Pre-1945 Levels, The Doc Concentrations Increased By 45% After 1960, The Mean Do C-14 Depletion In Recent Elb Ice Relative To Atmospheric (Co2)-C-14 Of 32% Being Attributed To Fossil-Fuel Sources. (Doc)-C-14 Content Of Ice Deposited During The Bomb-Peak Era (1955-1980) Closely Followed Atmospheric (Co2)-C-14 Changes Caused By Atmospheric Nuclear Tests, Suggesting The Living Biosphere As The Main Biogenic Source Of Doc In Summer In This Region. Elb Data Contrast With Those Previously Obtained In Summer Alpine (Western Europe) Ice In Which A Post-1950 Doubling Of Doc Was Observed And Attributed To Enhanced Emissions Of Organic Compounds From Vegetation In France. This Regional Difference Is Discussed With Respect To Changes Of Biogenic Organic Compound Emissions In Response To Past Change Of Use-Land And Global Warming. Elb Data Document, For The First Time, Changes Of Doc And (Doc)-C-14 In Winter Mountain Ice Showing An Increase By 44% Of Doc Levels Associated With A C-14 Signature Being 47% Lower Than That Of Atmospheric (Co2)-C-14 In Elb Ice Deposited After 1960. The C-14 Winter Elb Ice Record Followed Atmospheric (Co2)-C-14 Changes With A Delay Of Similar To 3 Years, Suggesting That Remaining Emissions From The Living Biosphere, Together With A Small Contribution From Wood Burning, Are The Main Biogenic Sources Of Doc In Winter In This Region.
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Leriche, M., Tulet, P., Deguillaume, L., Burnet, F., Colomb, A., Borbon, A., et al. (2024). Measurement Report: Bio-Physicochemistry Of Tropical Clouds At Maïdo (Réunion, Indian Ocean): Overview Of Results From The Bio-Maïdo Campaign. Atmospheric Chemistry And Physics, 242(7), 4129–4155.
Abstract: The Bio-Maido (Bio-Physicochemistry Of Tropical Clouds At Maido: Processes And Impacts On Secondary Organic Aerosols Formation) Campaign Was Conducted From 13 March To 4 April 2019 On The Tropical Island Of Reunion. The Main Objective Of The Project Was To Improve Understanding Of Cloud Impacts On The Formation Of Secondary Organic Aerosols (Soa) From Biogenic Volatile Organic Compound (Bvoc) Precursors In A Tropical Environment. Instruments Were Deployed At Five Sites: A Receptor Site, Maido Observatory (Mo) At 2165 M A.S.L. And Four Sites Along The Slope Of The Maido Mountain. Observations Include Measurements Of Volatile Organic Compounds (Vocs) And Characterization Of The Physical, Chemical And Biological (Bacterial Diversity And Culture-Based Approaches) Properties Of Aerosols And Cloud Water. Turbulent Parameters Of The Boundary Layer, Radiative Fluxes And Emissions Fluxes Of Bvocs From The Surrounding Vegetation Were Measured To Help Interpret Observed Chemical Concentrations In The Different Phases. Dynamical Analyses Showed Two Preferred Trajectory Routes For Air Masses Arriving At Mo During The Daytime. Both Trajectories Correspond To Return Branches Of The Trade Winds Associated With Upslope Thermal Breezes, Where Air Masses Likely Encountered Cloud Processing. The Highest Mixing Ratios Of Oxygenated Vocs (Ovocs) Were Measured Above The Site Located In The Endemic Forest And The Highest Contribution Of Ovocs To Total Vocs At Mo. Chemical Compositions Of Particles During Daytime Showed Higher Concentrations Of Oxalic Acid, A Tracer Of Cloud Processing And Photochemical Aging, And A More Oxidized Organic Aerosol At Mo Than At Other Sites. Approximately 20 % Of The Dissolved Organic Compounds Were Analyzed. Additional Analyses By Ultra-High-Resolution Mass Spectrometry Will Explore The Complexity Of The Missing Cloud Organic Matter.
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Liébault, F., Melun, G., Piton, G., Chapuis, M., Passy, P., & Tacon, S. (2024). Channel Change During Catastrophic Flood: Example Of Storm Alex In The Vesubie And Roya Valleys. Geomorphology, 4464.
Abstract: Documenting And Interpreting Channel Responses To Catastrophic Floods Help Understanding How Rapid Fluvial Metamorphosis Can Propagate In A Catchment Under Sediment Cascading Effects. The Recent Example Of The October 2020 Storm Alex In Se France (Similar To 500 Mm Of Rain In 24 H) Provides A Unique Opportunity To Investigate Major Geomorphic Responses Along 70 Km Of Two Confined Alpine Valleys (V & Eacute;Subie And Roya) And To Link Them To Sediment Wave Initiation And Propagation. Gis-Based Analysis Of Remote Sensing Data (High-Resolution Ortho-Imagery And Airborne Lidar Data) Acquired Before And After The Flood Allowed Combining Channel Changes With Sediment Erosion And Deposition Along A 35-Km Reach Of The V & Eacute;Subie, Including The Most Impacted Portions Of The Valley. In The Roya, The Analysis Was Restricted To 2D Morphological Changes Reconstructed With The Sequence Of Ortho-Imagery. Archives Of Aerial Imagery Were Also Used To Integrate The Storm Impact In The Historical Trajectory Of The Rivers. The Reconstruction Of Geomorphic Responses Shows A Quasi-Continuous Fluvial Metamorphosis Along The Investigated Stream Networks, With Dramatic Active Channel Widening And Aggradation, Having No Antecedent Analogs During The Last 70 Years In Both Valleys. The Different Glacial Imprints Between The Two Valleys Are Considered A Key Factor Explaining The Exacerbated Channel Response In The V & Eacute;Subie, Where A Braided Channel Emerged Along A 35-Km River Length. Many Evidences Strongly Support That The Fuelling Effect Of Alluvial Storage Is A Key Element Of The Sediment Cascade At The Origin Of The Braided Channel Formation. This Regional Case Study Allows Us To Discuss The Critical Role Of Floodplain And Terrace Erosion In The Formation Of The Post-Flood Braided Channel, And To Compare The Geomorphic Impact Of The Storm With Similar Reported Cases In The Literature.
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Manrique, M., Consonni, V., Boubenia, S., Roussel, H., Zeghouane, M., Labau, S., et al. (2024). Enhancing The Output Voltage Of Piezoelectric Nanogenerators Based On Zno Nanowires Grown By Chemical Bath Deposition Using Compensatory Cu Doping. Energy Technology, .
Abstract: The Screening Effect In Zno Nanowires (Nws) Coming From The High Density Of Free Electrons Has Emerged As One Of The Major Issues For Their Efficient Integration Into Piezoelectric Devices. Herein, The Compensatory Cu Doping Of Zno Nws Grown By Chemical Bath Deposition In The High-Ph Region Using Cu(No3)2 And Ammonia As Chemical Additives Is Developed And The Effects Of A Postdeposition Thermal Annealing Under Oxygen Atmosphere Are Investigated. It Is Shown That The Cu Dopants Are Incorporated Into Zno Nws With An Atomic [Cu]/[Zn] Ratio In The Range Of 50-65 Ppm And Undergo A Migration Process Into Their Bulk After Thermal Annealing. Importantly, The Electrical Resistivity Of Cu-Doped Zno Nws Is Found To Increase By A Factor Of 4 Compared To Unintentionally N-Doped Zno Nws. The Increase Is Even More Pronounced After Different Thermal Annealing, Reaching A Factor Exceeding 100, Which Is Explained By The Redistribution Of Hydrogen- And Nitrogen-Related Defects Along With The Thermal Activation Of Cu Dopants. Additionally, It Is Revealed That A Rigid Piezoelectric Nanogenerator Based On A Cu-Doped Zno Nw Matrix Exhibits The Highest Output Voltage And Effective Piezoelectric Coefficient D33Eff Thanks To The Reduction Of The Screening Effect, Opening Perspectives In The Field Of Piezoelectric Devices. Cu-Doped Zno Nanowires (Nws) Grown By Chemical Bath Deposition Exhibited A Free Electron Density Decrease Of 50% As Compared To Pristine Zno Nws. Additionally, Cu-Doped Zno Nw Based Piezoelectric Nanogenerators Showed The Highest Output Voltage Along With The Effective Piezoelectric Coefficient At Different Mechanical Stress Conditions.Image (C) 2024 Wiley-Vch Gmbh
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Marsal, A., Sauvain, J., Thomas, A., Lyon-Caen, S., Borlaza, L., Philippat, C., et al. (2024). Effects Of Personal Exposure To The Oxidative Potential Of Pm<Sub>2.5</Sub> On Oxidative Stress Biomarkers In Pregnant Women. Science Of The Total Environment, 9119.
Abstract: Oxidative Stress Is A Prominent Pathway For The Health Effects Associated With Fine Particulate Matter (Pm2.5) Exposure. Oxidative Potential (Op) Of Pm Has Been Associated To Several Health Endpoints, But Studies On Its Impact On Biomarkers Of Oxidative Stress Remains Insufficient. 300 Pregnant Women From The Sepages Cohort (France) Carried Personal Pm2.5 Samplers For A Week And Op Was Measured Using Ascorbic Acid (Aa) And Dithiothreitol (Dtt) Assays, And Normalized By 1) Pm2.5 Mass (Opm) And 2) Sampled Air Volume (Opv). A Pool Of Three Urine Spots Collected On The 7Th Day Of Pm Sampling Was Analyzed For Biomarkers, Namely 8-Hydroxy-2-Deoxyguanosine (8-Ohdg), Malondialdehyde (Mda) And 8-Isoprostaglandin-F2 Alpha (8-Isopgf2 Alpha). Associations Were Investigated Using Adjusted Multiple Linear Regressions. Op Effects Were Additionally Investigated By Stratifying By Median Pm2.5 Concentration (14 Mu G M(-3)). In The Main Models, No Association Was Observed With 8-Isopgf2 Alpha, Nor Mda. An Interquartile Range (Iqr) Increase In Opmaa Exposure Was Associated With Increased 8-Ohdg (Percent Change: 6.2 %; 95 % Ci: 0.2 % To 12.6 %). In The Stratified Analysis, Exposure To Opmaa Was Associated With 8-Ohdg For Participants Exposed To Low Levels Of Pm2.5 (Percent Change: 11.4 %; 95 % Ci: 3.3 % To 20.1 %), But Not For Those Exposed To High Levels (Percent Change: -1.0 %; 95 % Ci: -10.6 % To 9.6 %). Associations For Opmdtt Also Followed A Similar Pattern (P-Values For Opmaa-Pm And Opmdtt-Pm Interaction Terms Were 0.12 And 0.11, Respectively). Overall, Our Findings Suggest That Opmaa May Be Associated With Increased Dna Oxidative Damage. This Association Was Not Observed With Pm2.5 Mass Concentration Exposure. The Effects Of Opmaa In 8-Ohdg Tended To Be Stronger At Lower (Below Median) Vs. Higher Concentrations Of Pm2.5. Further Epidemiological, Toxicological And Aerosol Research Are Needed To Further Investigate The Opmaa Effects On 8-Ohdg And The Potential Modifying Effect Of Pm Mass Concentration On This Association.
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Mayer, L., Degrendele, C., Senk, P., Kohoutek, J., Pribylová, P., Kukucka, P., et al. (2024). Widespread Pesticide Distribution In The European Atmosphere Questions Their Degradability In Air. Environmental Science & Technology, 585(7), 3342–3352.
Abstract: Risk Assessment Of Pesticide Impacts On Remote Ecosystems Makes Use Of Model-Estimated Degradation In Air. Recent Studies Suggest These Degradation Rates To Be Overestimated, Questioning Current Pesticide Regulation. Here, We Investigated The Concentrations Of 76 Pesticides In Europe At 29 Rural, Coastal, Mountain, And Polar Sites During The Agricultural Application Season. Overall, 58 Pesticides Were Observed In The European Atmosphere. Low Spatial Variation Of 7 Pesticides Suggests Continental-Scale Atmospheric Dispersal. Based On Concentrations In Free Tropospheric Air And At Arctic Sites, 22 Pesticides Were Identified To Be Prone To Long-Range Atmospheric Transport, Which Included 15 Substances Approved For Agricultural Use In Europe And 7 Banned Ones. Comparison Between Concentrations At Remote Sites And Those Found At Pesticide Source Areas Suggests Long Atmospheric Lifetimes Of Atrazine, Cyprodinil, Spiroxamine, Tebuconazole, Terbuthylazine, And Thiacloprid. In General, Our Findings Suggest That Atmospheric Transport And Persistence Of Pesticides Have Been Underestimated And That Their Risk Assessment Needs To Be Improved.
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Médieu, A., Point, D., Sonke, J., Angot, H., Allain, V., Bodin, N., et al. (2024). Stable Tuna Mercury Concentrations Since 1971 Illustrate Marine Inertia And The Need For Strong Emission Reductions Under The Minamata Convention. Environmental Science & Technology Letters, 111(3), 250–258.
Abstract: Humans Are Exposed To Toxic Methylmercury Mainly By Consuming Marine Fish. While Reducing Mercury Emissions And Releases Aims To Protect Human Health, It Is Unclear How This Affects Methylmercury Concentrations In Seawater And Marine Biota. We Compiled Existing And Newly Acquired Mercury Concentrations In Tropical Tunas From The Global Ocean To Explore Multidecadal Mercury Variability Between 1971 And 2022. We Show The Strong Inter-Annual Variability Of Tuna Mercury Concentrations At The Global Scale, After Correcting For Bioaccumulation Effects. We Found Increasing Mercury Concentrations In Skipjack In The Late 1990S In The Northwestern Pacific, Likely Resulting From Concomitant Increasing Asian Mercury Emissions. Elsewhere, Stable Long-Term Trends Of Tuna Mercury Concentrations Contrast With An Overall Decline In Global Anthropogenic Mercury Emissions And Deposition Since The 1970S. Modeling Suggests That This Limited Response Observed In Tunas Likely Reflects The Inertia Of Surface Ocean Mercury With Respect To Declining Emissions, As It Is Supplied By Legacy Mercury That Accumulated In The Subsurface Ocean Over Centuries. To Achieve Measurable Declines In Mercury Concentrations In Highly Consumed Pelagic Fish In The Near Future, Aggressive Emission Reductions And Long-Term And Continuous Mercury Monitoring In Marine Biota Are Needed.
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Merlo-Reyes, A., Baduel, C., Duwig, C., & Ramirez, M. (2024). Risk Assessment Of Pesticides Used In The Eastern Avocado Belt Of Michoacan, Mexico: A Survey And Water Monitoring Approach. Science Of The Total Environment, 9169.
Abstract: Pesticides Use Raises Concerns Regarding Environmental Sustainability, As Pesticides Are Closely Linked To The Decline Of Biodiversity And Adverse Human Health Outcomes. This Study Proposed A Holistic Approach For Assessing The Potential Risks Posed By Pesticides For Human Health And The Environment In The Eastern Region Of Michoacan, Where Extensive Agricultural Lands, Especially Corn And Avocado Fields, Surround The Monarch Butterfly Biosphere Reserve. We Used A Combination Of Qualitative (Semi -Structured Interviews) And Quantitative (Chemical Analysis) Data. Fifty-Five Interviews With Smallholder Farmers Allowed Us To Identify Pesticide Types, Quantities, Frequencies, And Application Methods. A Robust And Precise Analytical Method Based On Solid -Phase Extraction And Lc-Ms/Ms Was Developed And Validated To Quantify 21 Different Pesticides In 16 Water Samples (Rivers, Wells, Runoff Areas). We Assessed Environmental And Human Health Risks Based On The Pesticides Detected In The Water Samples And Reported In The Interviews. The Interviews Revealed The Use Of 28 Active Ingredients, Including Glyphosate (29 % Of Respondents), Imidacloprid (27 %), And Benomyl (24 %). The Pesticide Analysis Showed The Presence Of 13 Different Pesticides And Degradation Products In The Water Samples. The Highest Concentrations Were Found For Imidacloprid (1195 Ngl-1) And Carbendazim (A Degradation Product Of Benomyl; 932 Ngl-1), Along With The Metabolite Of Pyrethroid Insecticides, 3-Pba (494 Ngl-1). The Risk Assessment Indicates That Among The Most Used Pesticides, The Fungicide Benomyl And Carbendazim Pose The Highest Risk To Human Health And Aquatic Ecosystems, Respectively. This Study Unveils Novel Insights On Agricultural Practices For The Avocado, A Globally Consumed Crop That Is Undergoing Rapid Production Expansion. It Calls For The Harmonisation Of Crop Protection With Environmental Responsibility, Safeguarding The Health Of The People Involved And The Surrounding Ecosystems.
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Michot, V., Corpetti, T., Ronchail, J., Espinoza, J., Arvor, D., Funatsu, B., et al. (2024). Seasonal Types In Homogeneous Rainfall Regions Of The Amazon Basin. International Journal Of Climatology, 444(4), 1224–1244.
Abstract: Due To Its Size And Geographical Features, Different Average Annual Rainfall Regimes Co-Exist In The Amazon Basin, With Distinct Year-To-Year Variability Dependent On Regions Within The Basin. In This Study, We Define And Explain The Seasonal Regional Types Of Annual Regimes, That Is, Years With Similar Seasonal Anomalies. Our Work Is Based On A 205 Rain Gauge Network Distributed Over Five Amazonian Countries, Spanning A Period Over 30 Years. Using A Spectral Clustering Method, We Identified Seven Sub-Regions Within The Basin In Which Annual Rainfall Regimes Are Spatially Homogenous. For Each Sub-Domain, We Estimated Specific Parameters That Characterize The Rainy Season (Onset And Demise Dates, Sign And Duration Of Rainfall Anomalies). Finally, Using Spectral Analysis We Identified Between Two And Four 'Seasonal Type' Of Precipitation In These Seven Sub-Domains. Most Of These Seasonal Types Are In Phase With The Large-Scale Atmospheric Circulation, Which Explains The Temporal Link With Rainfall Anomalies. The Seasonal Types Result Of The Superposition Of Inter-Annual And Intra-Seasonal Variability Whose Factors Are Then Difficult To Identify And Attribute. Part Of The Rainfall Anomalies Characterizing Seasonal Types Is Related To The Inter-Annual Variability Of The Sea Surface Temperature In The Atlantic Or The Pacific Oceans, Especially In The Northeast And Southeast Part Of The Amazon Basin, Whereas In Other Parts, Strong Intra-Seasonal And Local Factors Have A Larger Impact. The Same Sign And Duration Of Anomalies Do Not Concomitantly Affect The Various Regions Of The Amazon Basin, Confirming That One Mode Of Variability Does Not Homogeneously Affect Precipitation In Different Parts Of The Basin. Based On Rain Gauges Data And Spectral Analysis, We Identified Between Two And Four 'Seasonal Type' Of Precipitation, Compared With The Historical Mean Seasonal Regime, In Seven Homogeneous Rainfall Regions Of The Amazon Basin. Seasonal Types Result Of The Superposition Of Inter-Annual And Intra-Seasonal Variability. Part Of The Rainfall Anomalies Is Related To The Inter-Annual Variability Of The Sea Surface Temperature In The Surrounding Oceans, Especially In The Northeast And Southeast Part Of The Amazon Basin. Image
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Montoya-Coronado, V., Tedoldi, D., Castebrunet, H., Molle, P., & Kouyi, G. (2024). Data-Driven Methodological Approach For Modeling Rainfall-Induced Infiltration Effects On Combined Sewer Overflow In Urban Catchments. Journal Of Hydrology, 6326.
Abstract: Combined Sewer System Deterioration Poses Significant Challenges, Especially As It Leads To Substantial Volumes Of Permanent Infiltration Inflow (Pii) And Rain-Induced Infiltration (Rii) To Percolate Into Sewer Pipes. This Infiltration Increases The Risk Of Combined Sewer Overflow (Cso) Events And Reduces The Treatment Plant'S Efficiency By Diluting Raw Effluent. To Effectively Decrease Cso Volumes, It Is Crucial To Identify The Various Flow Components And Their Contribution To Overflow Volumes. In This Study, A Data-Driven Hydrological Model Was Developed, Conceptualizing The Surface Hydrological Processes As Well As The Interactions Between Soil Water And The Sewer System, Based On Long-Term Monitoring. Four Flow Components At The Outlet Of The Catchment Were Identified And Characterized: Wastewater, Surface Runoff, Pii, And Rii. The Model Was Applied And Evaluated Using Monitored Data From The Ecully Catchment In France. The Model Demonstrated Its Suitability In Replicating The Observed Hydrograph And Estimating Cso Volumes. Two Sewer System Scenarios Were Proposed, Investigating The Effect Of Partial And Complete Reduction Of Pii And Rii On Cso Volumes. The Results Showed A Reduction Of The Annual Cso Volume By 5 % To 7.5 %, And 12 % To 17 %, In The First And Second Scenario, Respectively. To Compare The Performance Of These Scenarios With Stormwater Management Strategies, Two Other Scenarios Were Considered Where Source Control Measures Allowed Infiltration Of The First 5 And 10 Mm Of Rainfall. The Results Demonstrated That These Measures Could, Respectively, Reduce Cso Volumes By 13 % To 48 % And Completely Eliminate Cso For Half Of The Events. This Study Highlights The Limitations Of Relying Solely On Pii And Rii Strategies To Eliminate Cso Events And Emphasizes The Necessity Of Considering Stormwater Management Strategies.
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Moreno, C., Krejci, R., Jaffrezo, J., Uzu, G., Alastuey, A., Andrade, M., et al. (2024). Tropical Tropospheric Aerosol Sources And Chemical Composition Observed At High Altitude In The Bolivian Andes. Atmospheric Chemistry And Physics, 242(5), 2837–2860.
Abstract: The Chemical Composition Of Pm 10 And Non-Overlapping Pm 2.5 Was Studied At The Summit Of Mt. Chacaltaya (5380 M A.S.L., Lat. – 16.346950 Degrees, Long. – 68.128250 Degrees) Providing A Unique Long-Term Record Spanning From December 2011 To March 2020. The Chemical Composition Of Aerosol At The Chacaltaya Global Atmosphere Watch (Gaw) Site Is Representative Of The Regional Background, Seasonally Affected By Biomass Burning Practices And By Nearby Anthropogenic Emissions From The Metropolitan Area Of La Paz-El Alto. Concentration Levels Are Clearly Influenced By Seasons With Minima Occurring During The Wet Season (December To March) And Maxima Occurring During The Dry And Transition Seasons (April To November). Ions, Total Carbon (Ec + Oc), And Saccharide Interquartile Ranges For Concentrations Are 558-1785, 384-1120, And 4.3-25.5 Ng M – 3 For Bulk Pm 10 And 917-2308, 519-1175, And 3.9-24.1 Ng M – 3 For Pm 2.5 , Respectively, With Most Of The Aerosol Seemingly Present In The Pm 2.5 Fraction. Such Concentrations Are Overall Lower Compared To Other High-Altitude Stations Around The Globe But Higher Than Amazonian Remote Sites (Except For Oc). For Pm 10 , There Is Dominance Of Insoluble Mineral Matter (33 %-56 % Of The Mass), Organic Matter (7 %-34 %), And Secondary Inorganic Aerosol (15 %-26 %). Chemical Composition Profiles Were Identified For Different Origins: Ec, No 3 – , Nh 4 + , Glucose, And C 2 O 4 2 – For The Nearby Urban And Rural Areas; Oc, Ec, No 3 – , K + , Acetate, Formate, Levoglucosan, And Some F – And Br – For Biomass Burning; Meso 3 – , Na + , Mg 2 + , K + , And Ca 2 + For Aged Marine Emissions From The Pacific Ocean; Arabitol, Mannitol, And Glucose For Biogenic Emissions; Na + , Ca 2 + , Mg 2 + , And K + For Soil Dust; And So 4 2 – , F – , And Some Cl – For Volcanism. Regional Biomass Burning Practices Influence The Soluble Fraction Of The Aerosol Between June And November. The Organic Fraction Is Present All Year Round And Has Both Anthropogenic (Biomass Burning And Other Combustion Sources) And Natural (Primary And Secondary Biogenic Emissions) Origins, With The Oc / Ec Mass Ratio Being Practically Constant All Year Round (10.5 +/- 5.7, Iqr 8.1-13.3). Peruvian Volcanism Has Dominated The So 4 2 – Concentration Since 2014, Though It Presents Strong Temporal Variability Due To The Intermittence Of The Sources And Seasonal Changes In The Transport Patterns. These Measurements Represent Some Of The First Long-Term Observations Of Aerosol Chemical Composition At A Continental High-Altitude Site In The Tropical Southern Hemisphere.
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Murfitt, J., Duguay, C., Picard, G., & Lemmetyinen, J. (2024). Forward Modelling Of Synthetic-Aperture Radar (Sar) Backscatter During Lake Ice Melt Conditions Using The Snow Microwave Radiative Transfer (Smrt) Model. Cryosphere, 181(2), 869–888.
Abstract: Monitoring Of Lake Ice Is Important To Maintain Transportation Routes, But In Recent Decades The Number Of In Situ Observations Have Declined. Remote Sensing Has Worked To Fill This Gap In Observations, With Active Microwave Sensors, Particularly Synthetic-Aperture Radar (Sar), Being A Crucial Technology. However, The Impact Of Wet Conditions On Radar And How Interactions Change Under These Conditions Have Been Largely Ignored. It Is Important To Understand These Interactions As Warming Conditions Are Likely To Lead To An Increase In The Occurrence Of Slush Layers. This Study Works To Address This Gap Using The Snow Microwave Radiative Transfer (Smrt) Model To Conduct Forward-Modelling Experiments Of Backscatter For Lake Oulujarvi In Finland. Experiments Were Conducted Under Dry Conditions, Under Moderate Wet Conditions, And Under Saturated Conditions. These Experiments Reflected Field Observations During The 2020-2021 Ice Season. Results Of The Dry-Snow Experiments Support The Dominance Of Surface Scattering From The Ice-Water Interface. However, Conditions Where Layers Of Wet Snow Are Introduced Show That The Primary Scattering Interface Changes Depending On The Location Of The Wet Layer. The Addition Of A Saturated Layer At The Ice Surface Results In The Highest Backscatter Values Due To The Larger Dielectric Contrast Created Between The Overlying Dry Snow And The Slush Layer. Improving The Representation Of These Conditions In Smrt Can Also Aid In More Accurate Retrievals Of Lake Ice Properties Such As Roughness, Which Is Key For Inversion Modelling Of Other Properties Such As Ice Thickness.
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Pant, M., Shahi, N., Remedio, A., Mall, R., Rai, S., & Bhatla, R. (2024). Representing Rainfall Extremes Over The Indo-Gangetic Plains Using Cordex-Core Simulations. Climate Dynamics, .
Abstract: The Indo-Gangetic Plain (Igp), Which Is The Site Of India'S Green Revolution, Covers Almost 15% Of The Country'S Landmass And Is Among The Most Extensively Fertile Lands Across The World. The Densely Populated Igp Region Bears Great Importance For The Socioeconomic Facets Of India And Contributes To A Major Share Of The Gdp Of The Country. The Present Study Demonstrates The Regional-Specific Assessment Of Summer Monsoon Precipitation And Associated Extremes With Dynamical And Thermodynamical Aspects Over The Igp Region Using High-Resolution Regional Climate Models (Rcms) Under The Cordex-Core Framework. The Analysis Reveals That The Eastern Parts Of The Igp Receive Low-To-Moderate Precipitation With A Higher Tail Than The Western Parts, Which Is Due To The Direction Of The Monsoon Low-Level Flow. The Observed Mean Precipitation Characteristics Are Well Represented By The Rcms. Further, The Research Identifies Extreme Precipitation Events Over The Igp And Conducts Comprehensive Analysis To Understand Their Underlying Mechanisms. It Has Been Observed That Extreme Precipitation Events Are Linked With The Moisture Transport Associated With Trough Activity And Instability, And Rcms Are Capable In Representing The Observed Precipitation Extremes And Underlying Mechanisms At Localized Scales. Overall, This Study Represents A Significant Step Forward In Understanding The Evolution Of Spatio-Temporal Variability Of Precipitation Over The Igp Region, Where Agriculture Is A Major Economic Activity And Millions Of People Depend On Rainfed Agriculture.
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Piton, G., Cohen, M., Flipo, M., Nowak, M., Chapuis, M., Melun, G., et al. (2024). Large In-Stream Wood Yield During An Extreme Flood (Storm Alex, October 2020, Roya Valley, France): Estimating The Supply, Transport, And Deposition Using Gis. Geomorphology, 4464.
Abstract: During Major Floods, Rivers Erode Their Banks And Thus Recruit Large Wood Pieces From The Riparian Zones. There Is Still A Lack Of Knowledge About The Transport Of Large Wood, The Volumes Involved And The Flux Distribution, I.E. The Large Wood Connectivity At Catchment Scale. During Storm Alex (October 2020), The French Roya Catchment (394 Km2) Experienced A Paroxysmal Morphogenic Flood Involving Massive Bank Erosion. The Riparian Vegetation Was Largely Recruited, With Large Wood Contributing To Logjams And Bridge Destruction. This Paper Presents A Methodology For Volumetric Assessment Of The Large Wood Fluxes Involved. Simple Approaches Are Used To (I) Quantify The Inputs From Stand Density Data From The National Forest Inventory And From Source Areas Based On Diachronic Analysis Of Active Channels Highlighting The Erosion Of 87 Ha Of Wooded Areas; And (Ii) Quantify The Volumes Deposited Via An Exhaustive Manual Digitisation Of 16,846 Pieces Of Large Wood Deposited On 59 Km Of Channels On The Roya And Its Tributaries. This Catchment-Scale, Large Wood Connectivity Analysis Shows That The Flood Recruited And Transported Downstream A Volume Of Around 14,000 M3 Of Large Wood (Uncertainty Range: 7000-29,500 M3). Drone Observations Of The Roya River Mouth In Italy And Satellite Images Showing A Raft Of Driftwood, Several Km Long, Drifting Off The Roya River Mouth In The Aftermath Of The Flood Corroborate Our Findings.
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Popov, M., Brankart, J., Capet, A., Cosme, E., & Brasseur, P. (2024). Ensemble Analysis And Forecast Of Ecosystem Indicators In The North Atlantic Using Ocean Colour Observations And Prior Statistics From A Stochastic Nemo-Pisces Simulator. Ocean Science, 202(1), 155–180.
Abstract: This Study Is Anchored In The H2020 Seamless Project (Https://Www.Seamlessproject.Org, Last Access: 29 January 2024), Which Aims To Develop Ensemble Assimilation Methods To Be Implemented In Copernicus Marine Service Monitoring And Forecasting Systems, In Order To Operationally Estimate A Set Of Targeted Ecosystem Indicators In Various Regions, Including Uncertainty Estimates. In This Paper, A Simplified Approach Is Introduced To Perform A 4D (Space-Time) Ensemble Analysis Describing The Evolution Of The Ocean Ecosystem. An Example Application Is Provided, Which Covers A Limited Time Period In A Limited Subregion Of The North Atlantic (Between 31 And 21 Circle W, Between 44 And 50.5 Circle N, Between 15 March And 15 June 2019, At A 1/4 Circle And A 1 D Resolution). The Ensemble Analysis Is Based On Prior Ensemble Statistics From A Stochastic Nemo (Nucleus For European Modelling Of The Ocean)-Pisces Simulator. Ocean Colour Observations Are Used As Constraints To Condition The 4D Prior Probability Distribution.As Compared To Classic Data Assimilation, The Simplification Comes From The Decoupling Between The Forward Simulation Using The Complex Modelling System And The Update Of The 4D Ensemble To Account For The Observation Constraint. The Shortcomings And Possible Advantages Of This Approach For Biogeochemical Applications Are Discussed In The Paper. The Results Show That It Is Possible To Produce A Multivariate Ensemble Analysis Continuous In Time And Consistent With The Observations. Furthermore, We Study How The Method Can Be Used To Extrapolate Analyses Calculated From Past Observations Into The Future. The Resulting 4D Ensemble Statistical Forecast Is Shown To Contain Valuable Information About The Evolution Of The Ecosystem For A Few Days After The Last Observation. However, As A Result Of The Short Decorrelation Timescale In The Prior Ensemble, The Spread Of The Ensemble Forecast Increases Quickly With Time. Throughout The Paper, A Special Emphasis Is Given To Discussing The Statistical Reliability Of The Solution.Two Different Methods Have Been Applied To Perform This 4D Statistical Analysis And Forecast: The Analysis Step Of The Ensemble Transform Kalman Filter (With Domain Localization) And A Monte Carlo Markov Chain (Mcmc) Sampler (With Covariance Localization), Both Enhanced By The Application Of Anamorphosis To The Original Variables. Despite Being Very Different, The Two Algorithms Produce Very Similar Results, Thus Providing Support To Each Other'S Estimates. As Shown In The Paper, The Decoupling Of The Statistical Analysis From The Dynamical Model Allows Us To Restrict The Analysis To A Few Selected Variables And, At The Same Time, To Produce Estimates Of Additional Ecological Indicators (In Our Example: Phenology, Trophic Efficiency, Downward Flux Of Particulate Organic Matter). This Approach Can Easily Be Appended To Existing Operational Systems To Focus On Dedicated Users' Requirements, At A Small Additional Cost, As Long As A Reliable Prior Ensemble Simulation Is Available. It Can Also Serve As A Baseline To Compare With The Dynamical Ensemble Forecast And As A Possible Substitute Whenever Useful.
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Pühl, M., Roiger, A., Fiehn, A., Negron, A., Kort, E., Schwietzke, S., et al. (2024). Aircraft-Based Mass Balance Estimate Of Methane Emissions From Offshore Gas Facilities In The Southern North Sea. Atmospheric Chemistry And Physics, 242(2), 1005–1024.
Abstract: Atmospheric Methane (Ch 4 ) Concentrations Have More Than Doubled Since The Beginning Of The Industrial Age, Making Ch 4 The Second Most Important Anthropogenic Greenhouse Gas After Carbon Dioxide (Co 2 ). The Oil And Gas Sector Represents One Of The Major Anthropogenic Ch 4 Emitters As It Is Estimated To Account For 22 % Of Global Anthropogenic Ch 4 Emissions. An Airborne Field Campaign Was Conducted In April-May 2019 To Study Ch 4 Emissions From Offshore Gas Facilities In The Southern North Sea With The Aim Of Deriving Emission Estimates Using A Top-Down (Measurement-Led) Approach. We Present Ch 4 Fluxes For Six Uk And Five Dutch Offshore Platforms Or Platform Complexes Using The Well-Established Mass Balance Flux Method. We Identify Specific Gas Production Emissions And Emission Processes (Venting And Fugitive Or Flaring And Combustion) Using Observations Of Co-Emitted Ethane (C 2 H 6 ) And Co 2 . We Compare Our Top-Down Estimated Fluxes With A Ship-Based Top-Down Study In The Dutch Sector And With Bottom-Up Estimates From A Globally Gridded Annual Inventory, Uk National Annual Point-Source Inventories, And Operator-Based Reporting For Individual Dutch Facilities. In This Study, We Find That All The Inventories, Except For The Operator-Based Facility-Level Reporting, Underestimate Measured Emissions, With The Largest Discrepancy Observed With The Globally Gridded Inventory. Individual Facility Reporting, As Available For Dutch Sites For The Specific Survey Date, Shows Better Agreement With Our Measurement-Based Estimates. For All The Sampled Dutch Installations Together, We Find That Our Estimated Flux Of (122.9 +/- 36.8) Kg H – 1 Deviates By A Factor Of 0.64 (0.33-12) From Reported Values (192.8 Kg H – 1 ). Comparisons With Aircraft Observations In Two Other Offshore Regions (The Norwegian Sea And The Gulf Of Mexico) Show That Measured, Absolute Facility-Level Emission Rates Agree With The General Distribution Found In Other Offshore Basins Despite Different Production Types (Oil, Gas) And Gas Production Rates, Which Vary By 2 Orders Of Magnitude. Therefore, Mitigation Is Warranted Equally Across Geographies.
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Richard, G. (2024). Roll Waves In A Predictive Model For Open-Channel Flows In The Smooth Turbulent Case. Journal Of Fluid Mechanics, 9839.
Abstract: A Depth-Averaged Model For Turbulent Open-Channel Flows With Breaking Roll Waves On A Sloping Smooth Bottom Is Derived Under An Assumption Of Independence Between The Wall Turbulence And The Roller Turbulence. The Model Includes Four Variables – The Water Depth, The Average Velocity, And Two Variables Called Enstrophy, The Shear Enstrophy And The Roller Enstrophy – Which Take Into Account The Deviations Of The Velocity With Respect To Its Depth-Averaged Value Due To Shear Effect And Roller Turbulence, Respectively. The Four Equations Of The Model Are The Mass, Momentum, Energy And Shear Enstrophy Balance Equations, With The Mathematical Structure Of The Euler Equations Of Compressible Fluids, With An Additional Transport Equation And With Source Terms. The System Is Hyperbolic. The Roller Enstrophy Is Created By Shocks. A Non-Zero Value Of The Roller Enstrophy Indicates A Breaking Wave And A Turbulent Roller. The Model Is Solved By A Fast And Well-Known Numerical Scheme, With An Explicit Finite-Volume Method In One Step. The Model Is Used To Simulate Periodic And Natural Roll Waves With A Good Agreement With Existing Experimental Results. There Is No Parameter To Calibrate In The Model, Which Gives It A Predictive Character.
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Rossi, F., Duchaine, C., Tignat-Perrier, R., Joly, M., Larose, C., Dommergue, A., et al. (2024). Temporal Variations Of Antimicrobial Resistance Genes In Aerosols: A One-Year Monitoring At The Puy De Dome Summit (Central France). Science Of The Total Environment, 9129.
Abstract: The Recent Characterization Of Antibiotic Resistance Genes (Args) In Clouds Evidenced That The Atmosphere Actively Partakes In The Global Spreading Of Antibiotic Resistance Worldwide. Indeed, The Outdoor Atmosphere Continuously Receives Large Quantities Of Particles Of Biological Origins, Emitted From Both Anthropogenic Or Natural Sources At The Near Earth'S Surface. Nonetheless, Our Understanding Of The Composition Of The Atmospheric Resistome, Especially At Mid-Altitude (I.E. Above 1000 M A.S.L.), Remains Largely Limited. The Atmosphere Is Vast And Highly Dynamic, So That The Diversity And Abundance Of Args Are Expected To Fluctuate Both Spatially And Temporally. In This Work, The Abundance And Diversity Of Args Were Assessed In Atmospheric Aerosol Samples Collected Weekly Between July 2016 And August 2017 At The Mountain Site Of Puy De Dome (1465 M A.S.L., Central France). Our Results Evidence The Presence Of 33 Different Subtypes Of Args In Atmospheric Aerosols, Out Of 34 Assessed, Whose Total Concentration Fluctuated Seasonally From 59 To 1.1 X 10(5) Copies M(-3) Of Air. These Were Heavily Dominated By Genes From The Quinolone Resistance Family, Notably The Qepa Gene Encoding Efflux Pump Mechanisms, Which Represented >95 % Of Total Args Concentration. Its Abundance Positively Correlated With That Of Bacteria Affiliated With The Genera Kineococcus, Neorhizobium, Devosia Or Massilia, Ubiquitous In Soils. This, Along With The High Abundance Of Sphingomonas Species, Points Toward A Large Contribution Of Natural Sources To The Airborne Args. Nonetheless, The Increased Contribution Of Macrolide Resistance (Notably The Erm35 Gene) During Winter Suggests A Sporadic Diffusion Of Args From Human Activities. Our Observations Depict The Atmosphere As An Important Vector Of Args From Terrestrial Sources. Therefore, Monitoring Args In Airborne Microorganisms Appears Necessary To Fully Understand The Dynamics Of Antimicrobial Resistances In The Environment And Mitigate The Threats They May Represent.
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Sadhvi, K., Suresh, I., Lengaigne, M., Izumo, T., Penduff, T., Molines, J., et al. (2024). Intrinsic Versus Wind-Forced Great Whirl Non-Seasonal Variability. Journal Of Geophysical Research-Oceans, 1291(2).
Abstract: The Great Whirl (Gw) Is A Quasi-Permanent Anticyclonic Eddy That Appears Every Summer Monsoon Offshore Of The Somalia Upwelling. The Annual Cycle Of The Gw Is Well Described, But Deviations From Its Mean Seasonal Cycle (Hereafter Non-Seasonal Variability) Have Been Less Explored. Satellite Observations Reveal That The Leading Mode Of Summer Non-Seasonal Sea-Level Variability In This Region Is Associated With Similar To 100-Km Northward Or Southward Gw Shifts From Its Climatological Position. Northward Shifts Are Associated With A Stronger Gw, And Two Cold, Productive Coastal Upwelling Wedges At 5 Degrees N And 10 Degrees N. Southward Shifts Are Associated With A Weaker Gw, No Wedge At 5 Degrees N And A Single Stronger-Than-Usual Cold And Productive Wedge At 10 Degrees N. An Eddy-Permitting (25-Km Resolution) 50-Member Ensemble Ocean Simulation Reproduces This Gw Variability Well. It Indicates That The Non-Seasonal Gw Variability Has A Short Similar To 20 Days Timescale Intrinsic Component, Associated With The Gw Interaction With Mesoscale Eddies, And A Lower-Frequency, Similar To 100 Days Externally Forced Component. Intrinsic Variability Dominates At Both Subseasonal (Two Thirds Of The Variance) And Interannual Timescales (57% Of The Variance). The Externally Forced Signal Results From Shifts In The Probability Distribution Of The Subseasonal Gw Position (E.G., More Likely Northward Than Southward Shifted Instantaneous Gw Positions Over A Season). The Mechanism For This External Forcing Is Not Entirely Clear, But It Appears To Be Related To The Rossby Wave Response To Offshore Wind Stress Curl Forcing, Which Evolves Into A North-South Dipole That Projects Onto The Gw Variability Pattern. The Great Whirl (Gw) Is A Similar To 500-Km Diameter Oceanic Eddy That Forms Each Summer Off The Somalia Coast. The Gw Influences The Temperature And Biological Productivity Of The Somalia Coastal Upwelling. The Gw Seasonal Cycle, Including Its Northward Movement At The End Of The Monsoon, Is Known. Here, We Study Deviations From This Mean Seasonal Cycle. The Gw Exhibits Fast (Typically 20 Days Long), Similar To 100-Km Northward Or Southward Displacements. These Displacements Result From Interactions With Smaller Neighboring Oceanic Eddies, And Are Hence The Consequence Of An Intrinsic Ocean Dynamics, Rather Than Atmospheric Forcing. The Gw Is More Pronounced When Displaced Northward, And The Somalia Coastal Upwelling Has Two Clear “Wedges” Of Cold, Plankton-Rich Water At 5 Degrees And 10 Degrees N. When Displaced Southward, The Gw Is Less Pronounced, And There Is A Single, Stronger-Than-Usual Wedge Of Cold Water At 10 Degrees N. We Also Show That Atmospheric Forcing Can Induce Seasonal Gw Displacements, By Making, For Example, Northward Events More Likely Than The Southward. Thus, The Seasonal Mean Gw Position Has Both A Predictable (Due To Atmospheric Forcing) And Slightly Larger Unpredictable (Due To Interactions With Eddies) Component. We Propose That The Atmospheric Forcing Influences The Fast Oscillations Of The Gw Through Slow Oceanic Adjustment To Wind Variations Further East. The Great Whirl (Gw) Non-Seasonal Variability Is Dominated By Similar To 100-Km Northward Or Southward Shifts Relative To Its Climatological Position Those Shifts Induce Sea Level, Surface Temperature And Chlorophyll Signals Those Gw Displacements Have A Fast (Similar To 20 Days) Intrinsic Variability Component And A Slower, Seasonal Forced Component
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Shangguan, Y., Zhuang, X., Querol, X., Li, B., Moreno, N., Trechera, P., et al. (2024). Physicochemical Characteristics And Oxidative Potential Of Size-Segregated Respirable Coal Mine Dust: Implications For Potentially Hazardous Agents And Health Risk Assessment. International Journal Of Coal Geology, 2822.
Abstract: The Health Risks Associated With Exposure To Respirable Dust In Coal Mines Have Been Attracted Much Attention By An Increasing Number Of Researchers. However, The Accurate Identification Of Potentially Hazardous Agents In Respirable Dusts And The Evaluation Of The Potential Health Risks Arising From It Still Remains Controversial To Varying Degrees. A Comprehensive Understanding Of The Physicochemical Properties Of Respirable Dust Is A Prerequisite And An Important Basis For Resolving This Controversy. Therefore, In This Study, The Particle Size Distribution And Morphology, Pore Structure, Mineralogical And Geochemical Patterns, And Oxidative Potential (Op) Of Respirable Coal Mine Dust Were Comprehensively Investigated. Stepwise Multiple Linear Regression Was Employed To Identify Dust Components Driving Op, Such As Anatase, Tobelite, Quartz, And Ankerite, In Respirable Coal Mine Dust, Along With Na, Ni, Se, W, And As. On This Basis, We Performed A Single-Factor Risk Prediction For Different Coal Mines By Considering Factors That May Impact Miners' Health, With The Analyses Yielding Somewhat Contradictory Results. Therefore, A Multifactor Integrated Prediction Model Is Proposed Using An Entropy-Based Technique For Order Preference By Similarity To The Ideal Solution To Categorize Coal Mines In The Study Area Into Three Risk Categories, High-, Medium-, And Low-Risk Dust Mines, Which Is Important For The Hierarchical Classification And Control Of Coal Mines And For Formulating Appropriate Dust Prevention And Control Measures.
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Sicaud, E., Fortier, D., Dedieu, J., & Franssen, J. (2024). Pairing Remote Sensing And Clustering In Landscape Hydrology For Large-Scale Change Identification: An Application To The Subarctic Watershed Of The George River (Nunavik, Canada). Hydrology And Earth System Sciences, 282(1), 65–86.
Abstract: For Remote And Vast Northern Watersheds, Hydrological Data Are Often Sparse And Incomplete. Landscape Hydrology Provides Useful Approaches For The Indirect Assessment Of The Hydrological Characteristics Of Watersheds Through Analysis Of Landscape Properties. In This Study, We Used Unsupervised Geographic Object-Based Image Analysis (Geobia) Paired With The Fuzzy C -Means (Fcm) Clustering Algorithm To Produce Seven High-Resolution Territorial Classifications Of Key Remotely Sensed Hydro-Geomorphic Metrics For The 1985-2019 Time Period, Each With A Frequency Of 5 Years. Our Study Site Is The George River Watershed (Grw), A 42 000 Km 2 Watershed Located In Nunavik, Northern Quebec (Canada). The Subwatersheds Within The Grw, Used As The Objects Of The Geobia, Were Classified As A Function Of Their Hydrological Similarities. Classification Results For The Period 2015-2019 Showed That The Grw Is Composed Of Two Main Types Of Subwatersheds Distributed Along A Latitudinal Gradient, Which Indicates Broad-Scale Differences In Hydrological Regimes And Water Balances Across The Grw. Six Classifications Were Computed For The Period 1985-2014 To Investigate Past Changes In Hydrological Regime. The Time Series Of Seven Classifications Showed A Homogenization Of Subwatershed Types Associated With Increases In Vegetation Productivity And In Water Contents In Soil And Vegetation, Mostly Concentrated In The Northern Half Of The Grw, Which Were The Major Changes Occurring In The Land Cover Metrics Of The Grw. An Increase In Vegetation Productivity Likely Contributed To An Augmentation In Evaporation And May Be A Primary Driver Of Fundamental Shifts In The Grw Water Balance, Potentially Explaining A Measured Decline Of About 1 % ( Similar To 0.16 Km 3 Yr – 1 ) In The George River'S Discharge Since The Mid-1970S. Permafrost Degradation Over The Study Period Also Likely Affected The Hydrological Regime And Water Balance Of The Grw. However, The Shifts In Permafrost Extent And Active Layer Thickness Remain Difficult To Detect Using Remote-Sensing-Based Approaches, Particularly In Areas Of Discontinuous And Sporadic Permafrost.
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Silué, F., Diawara, A., Koné, B., Diedhiou, A., Kouassi, A., Kouassi, B., et al. (2024). Assessment Of The Sensitivity Of The Mean Climate Simulation Over West Africa To Planetary Boundary Layer Parameterization Using Regcm5 Regional Climate Model. Atmosphere, 151(3).
Abstract: This Study Evaluates The Performance Of Two Planetary Boundary Parameterizations In Simulating The Mean Climate Of West Africa Using The Regional Climate Model Version 5 (Regcm5). These Planetary Boundary Parameterizations Are The Holtslag Scheme And The University Of Washington Scheme. Two Sets Of Three One-Year Simulations Were Carried Out At 25 Km Horizontal Resolution With Three Different Initial Conditions. The First Set Of Simulations Used The Holtslag Scheme (Hereafter Referred To As Hol), While The Second Used The University Of Washington (Uw) Scheme (Hereafter Referred To As Uw). The Results Displayed In This Study Are An Average Of The Three Simulations. During The Jjas Rainy Season, With Respect To Gpcp, Both Models Overestimated Total Rainfall In The Orographic Regions. The Uw Experiment Represented Total Rainfall Fairly Well Compared To Its Counterpart, Hol. Both Models Reproduced Convective Rainfall Well, With A Relatively Weak Dry Bias Over The Guinean Coast Subregion. Globally, Uw Performed Better Than Hol In Simulating Precipitation. The Pattern Of Near-Surface Temperature In Both Models Was Well Reproduced With A Higher Bias With Hol Than With Uw. Indeed, The Uw Scheme Led To A Cooling Effect Owing To The Reduction In Eddy Heat Diffusivity In The Lower Troposphere Contributing To Reduce The Bias. As A Consequence, The Height Of The Planetary Boundary Layer (Pbl) Was Best Simulated Using The Uw Scheme But Was Underestimated Compared To Era5, While Using The Hol Scheme Failed To Capture The Height Of The Pbl. This Is Coherent With The Distribution Of Total Cloud Cover, Which Was Better Simulated With The Uw Scheme Compared To The Hol Scheme. This Study Shows That Use Of Both Planetary Boundary Parameterizations Leads To A Good Simulation Of Most Of The Climatological Characteristics Of The West African Region. Nevertheless, Use Of The Uw Scheme Contributes To A Better Performance Than Use Of The Hol Scheme, And The Differentiation Between The Two Schemes Is Significant Along The Guinea Coast And In Orographic Regions. In These Topographically Complex Regions, Uw Appears To Be More Appropriate Than Hol. This Study Emphasizes The Importance Of Planetary Boundary Parameterizations For Accurately Simulating Climate Variables And For Improving Climate Forecasts And Projections In West Africa.
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Spolaor, A., Scoto, F., Larose, C., Barbaro, E., Burgay, F., Bjorkman, M., et al. (2024). Climate Change Is Rapidly Deteriorating The Climatic Signal In Svalbard Glaciers. Cryosphere, 181(1), 307–320.
Abstract: The Svalbard Archipelago Is Particularly Sensitive To Climate Change Due To The Relatively Low Altitude Of Its Main Ice Fields And Its Geographical Location In The Higher North Atlantic, Where The Effect Of Arctic Amplification Is More Significant. The Largest Temperature Increases Have Been Observed During Winter, But Increasing Summer Temperatures, Above The Melting Point, Have Led To Increased Glacier Melt. Here, We Evaluate The Impact Of This Increased Melt On The Preservation Of The Oxygen Isotope ( Delta 18 O) Signal In Firn Records. Delta 18 O Is Commonly Used As A Proxy For Past Atmospheric Temperature Reconstructions, And, When Preserved, It Is A Crucial Parameter To Date And Align Ice Cores. By Comparing Four Different Firn Cores Collected In 2012, 2015, 2017 And 2019 At The Top Of The Holtedahlfonna Ice Field (1100 M A.S.L.), We Show A Progressive Deterioration Of The Isotope Signal, And We Link Its Degradation To The Increased Occurrence And Intensity Of Melt Events. Our Findings Indicate That, Starting From 2015, There Has Been An Escalation In Melting And Percolation Resulting From Changes In The Overall Atmospheric Conditions. This Has Led To The Deterioration Of The Climate Signal Preserved Within The Firn Or Ice. Our Observations Correspond With The Model'S Calculations, Demonstrating An Increase In Water Percolation Since 2014, Potentially Reaching Deeper Layers Of The Firn. Although The Delta 18 O Signal Still Reflects The Interannual Temperature Trend, More Frequent Melting Events May In The Future Affect The Interpretation Of The Isotopic Signal, Compromising The Use Of Svalbard Ice Cores. Our Findings Highlight The Impact And The Speed At Which Arctic Amplification Is Affecting Svalbard'S Cryosphere.
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Stefanini, C., Macelloni, G., Leduc-Leballeur, M., Favier, V., Pohl, B., & Picard, G. (2024). Extreme Events Of Snow Grain Size Increase In East Antarctica And Their Relationship With Meteorological Conditions. Cryosphere, 181(2), 593–608.
Abstract: This Study Explores The Seasonal Variations In Snow Grain Size On The East Antarctic Plateau, Where Dry Metamorphism Occurs, By Using Microwave Radiometer Observations From 2000 To 2022. Local Meteorological Conditions And Large-Scale Atmospheric Phenomena Have Been Considered In Order To Explain Some Peculiar Changes In The Snow Grains. We Find That The Highest Ice Divide Is The Region With The Largest Grain Size In The Summer, Mainly Because The Wind Speed Is Low. Moreover, Some Extreme Grain Size Values With Respect To The Average (Over +3 Sigma) Were Identified. In These Cases, The Era5 Reanalysis Revealed A High-Pressure Blocking Close To The Onsets Of The Summer Increase In The Grain Size. It Channels Moisture Intrusions From The Mid-Latitudes, Through Atmospheric Rivers That Cause Major Snowfall Events Over The Plateau. If Conditions Of Weak Wind And Low Temperature Occur During The Following Weeks, Dry Snow Metamorphism Is Facilitated, Leading To Grain Growth. This Determines Anomalous High Maximums Of The Snow Grain Size At The End Of Summer. These Phenomena Confirm The Importance Of Moisture Intrusion Events In East Antarctica And Their Impact On The Physical Properties Of The Ice Sheet Surface, With A Co-Occurrence Of Atmospheric Rivers And Seasonal Changes In The Grain Size With A Significance Of Over 95 %.
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Stefanini, C., Macelloni, G., Leduc-Leballeur, M., & Picard, G. (2024). Influence Of Surface Snow Properties On An 89-Ghz Brightness Temperature Extreme Event At Dome Fuji, Antarctica. Ieee Geoscience And Remote Sensing Letters, 212.
Abstract: Microwave Brightness Temperatures Observed In Antarctica At 89 Ghz From The Advanced Microwave Sounding Unit B (Amsu-B) Point Out An Exceptional Decrease Of 57 K At Dome Fuji ( 77.31(Degrees)S, 39.70(Degrees)E) During The 2019-2020 Summer. The Grain Size Index (Gsi) Based On 89 And 150 Ghz From Amsu-B And Independent Observations At 89 Ghz From The Advanced Microwave Scanning Radiometer 2 (Amsr-2) Also Show Concurrent Unusual Values. To Explain Such Event, A Theoretical Analysis Was Carried Out By Means Of A Radiative Transfer Model. We Explore The Sensitivity Of Brightness Temperature To Surface Snow Properties Focusing On December, Just Before The Decrease, And April, At Its End. Results Confirm That This Variation Is Mainly Related To An Increase In Snow Grain Size. A Decrease In Snow Density Is Also Involved As Suggested By The Increase In Brightness Temperature At 1.4 Ghz From Soil Moisture And Ocean Salinity (Smos) And In The Polarization Ratio At 36 Ghz From Amsr-2. Extreme Values Observed At Multiple Frequencies, As Well As Peculiar Atmospheric Conditions Explored In A Previous Study, Confirm The Uniqueness Of This Event At Least On Decennial Scale.
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Sulca, J., Takahashi, K., Espinoza, J., Tacza, J., Zubieta, R., Mosquera, K., et al. (2024). A Multiple Linear Regression Model For The Prediction Of Summer Rainfall In The Northwestern Peruvian Amazon Using Large-Scale Indices. Climate Dynamics, .
Abstract: The Northwestern Peruvian Amazon (Nwpa) Basin (78.4-75.8 Degrees W, 7.9-5.4 Degrees S) Is An Important Region For Coffee And Rice Production In Peru. Currently, No Prediction Models Are Available For Estimating Rainfall In Advance During The Wet Season (January-February-March, Jfm). Hence, We Developed Multiple Linear Regression (Mlr) Models Using Predictors Derived From Sea Surface Temperature (Sst) Indices Of The Pacific, Atlantic, And Indian Oceans, Including Central El Nino (C), Eastern El Nino (E), Tropical South Atlantic (Tsatl), Tropical North Atlantic (Tnatl), Extratropical North Atlantic (Enatl), And Indian Ocean Basin-Wide With E And C Removed (Iobw*) Indices. Additionally, We Utilized Large-Scale Convection Indices, Namely, The Eastern Pacific Intertropical Convergence Zone (Itcze) And South American Monsoon System (Samsi) Indices, For The 1981-2018 Period. Rainfall In The Lowland Nwpa Exhibits A Bimodal Annual Cycle, Whereas Rainfall In The Highland Nwpa Exhibits A Unimodal Annual Cycle. The Mlr Model Can Be Used To Accurately Capture The Interannual Variability During The Wet Season In The Highland Nwpa By Utilizing Predictors Derived From The C And Samsi Indices. In Contrast, Regarding Rainfall In The Lowland Nwpa, The Pacific Sst Variability, Sams And Tropical North Atlantic Index Were Relevant. For Long Lead Times, The Mlr Model Provided Reliable Forecasts Of Jfm Rainfall Anomalies In The Highlands (R3, Approximately 2700 M Asl) As These Regions Are Governed By Pacific Variability. However, The Mlr Model Exhibited Limitations In Accurately Estimating The Wettest Jfm Season In The Highlands Due To The Absence Of A Predictor For The Amplified Effect Of The Madden-Julian Oscillation On Rainfall.
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Sundu, K., Freitag, J., Fourteau, K., & Löwe, H. (2024). A Microstructure-Based Parameterization Of The Effective Anisotropic Elasticity Tensor Of Snow, Firn, And Bubbly Ice. Cryosphere, 181(4), 1579–1596.
Abstract: Quantifying The Link Between Microstructure And Effective Elastic Properties Of Snow, Firn, And Bubbly Ice Is Essential For Many Applications In Cryospheric Sciences. The Microstructure Of Snow And Ice Can Be Characterized By Different Types Of Fabrics (Crystallographic And Geometrical), Which Give Rise To Macroscopically Anisotropic Elastic Behavior. While The Impact Of The Crystallographic Fabric Has Been Extensively Studied In Deep Firn, The Present Work Investigates The Influence Of The Geometrical Fabric Over The Entire Range Of Possible Volume Fractions. To This End, We Have Computed The Effective Elasticity Tensor Of Snow, Firn, And Ice By Finite-Element Simulations Based On 391 X-Ray Tomography Images Comprising Samples From The Laboratory, The Alps, Greenland, And Antarctica. We Employed A Variant Of Eshelby'S Tensor That Has Been Previously Utilized For The Parameterization Of Thermal And Dielectric Properties Of Snow And Utilized Hashin-Shtrikman Bounds To Capture The Nonlinear Interplay Between Density And Geometrical Anisotropy. From That We Derive A Closed-Form Parameterization For All Components Of The (Transverse Isotropic) Elasticity Tensor For All Volume Fractions Using Two Fit Parameters Per Tensor Component. Finally, We Used The Thomsen Parameter To Compare The Geometrical Anisotropy To The Maximal Theoretical Crystallographic Anisotropy In Bubbly Ice. While The Geometrical Anisotropy Clearly Dominates Up To Ice Volume Fractions Of Phi Approximate To 0.7 , A Thorough Understanding Of Elasticity In Bubbly Ice May Require A Coupled Elastic Theory That Includes Geometrical And Crystallographic Anisotropy.
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Tkachenko, K., & Jacobi, H. (2024). Electrical Charging Of Snow And Ice In Polar Regions And The Potential Impact On Atmospheric Chemistry. Environmental Science-Atmospheres, 4(2), 144–163.
Abstract: Charging Of The Ice-Vapor Interface Is A Well-Studied Topic In Ice Physics And Atmospheric Electrification. However, These Effects Were Not Yet Considered To Examine Chemical Processes In Snow In Polar Regions Because Electric Potentials At Ice Surfaces Have So Far Been Considered Insufficient To Initiate Chemical Reactions And Processes. In This Review, We Analyze Literature Data To Estimate Levels Of Electrification In Snow And Other Frozen Objects That Can Be Caused By Different Processes Occurring At The Earth'S Surface. This Analysis Demonstrates That Threshold Values Of Electric Field Strength Can Be Exceeded For The Appearance Of Corona Discharges And Even For The Formation Of Rayleigh Jets Due To Combined Effects Of Different Meteorological And Physical Processes. The Accumulation Of Electrical Charges Can Lead To Different Chemical Modifications Such As Electroosmotic Phenomena Or The Accumulation Of Impurities From The Atmosphere In Growing Ice Crystals. Moreover, Highly Energetic States That Occur And Dissipate In Microseconds As “Hot Spots” Have The Potential To Initiate Free Radical Processes And Even The Production Of Charged Aerosols. The Review Also Discusses In Detail Selected Field Observations To Point Out How Processes Driven By Electrical Charging May Help To Interpret These Observations, Which Are At Least Partly Inconsistent With Our Present Understanding Of Snow And Ice Chemistry. Finally, Some Approaches Are Presented How These Effects Can Be Studied In Field And Laboratory Experiments. A Further Development Of This New Field At The Intersection Of Ice Physics And Snow Chemistry Seems Very Promising For A Better Understanding Of Relevant Chemical Processes Related To The Cryosphere. Different Processes Can Lead To High Electrical Field Strengths In Snow And Ice In Polar Regions With The Potential To Initiate Free Radical Processes And A Number Of Other Chemical Modifications.
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Uchida, T., Jamet, Q., Dewar, W., Deremble, B., Poje, A., & Sun, L. (2024). Imprint Of Chaos On The Ocean Energy Cycle From An Eddying North Atlantic Ensemble. Journal Of Physical Oceanography, 545(3), 679–696.
Abstract: We Examine The Ocean Energy Cycle Where The Eddies Are Defined About The Ensemble Mean Of A Partially Air-Sea Coupled, Eddy -Rich Ensemble Simulation Of The North Atlantic. The Decomposition About The Ensemble Mean Leads To A Parameter -Free Definition Of Eddies, Which Is Interpreted As The Expression Of Oceanic Chaos. Using The Ensemble Framework, We Define The Reservoirs Of Mean And Eddy Kinetic Energy (Mke And Eke, Respectively) And Mean Total Dynamic Enthalpy (Mtde). We Opt For The Usage Of Dynamic Enthalpy (De) As A Proxy For Potential Energy Due To Its Dynamically Consistent Relation To Hydrostatic Pressure In Boussinesq Fluids And Nonreliance On Any Reference Stratification. The Curious Result That Emerges Is That The Potential Energy Reservoir Cannot Be Decomposed Into Its Mean And Eddy Components, And The Eddy Flux Of De Can Be Absorbed Into The Eke Budget As Pressure Work. We Find From The Energy Cycle That While Baroclinic Instability, Associated With A Positive Vertical Eddy Buoyancy Flux, Tends To Peak Around February, Eke Takes Its Maximum Around September In The Wind -Driven Gyre. Interestingly, The Energy Input From Mke To Eke, A Process Sometimes Associated With Barotropic Processes, Becomes Larger Than The Vertical Eddy Buoyancy Flux During The Summer And Autumn. Our Results Question The Common Notion That The Inverse Energy Cascade Of Wintertime Eke Energized By Baroclinic Instability Within The Mixed Layer Is Solely Responsible For The Summer -To -Autumn Peak In Eke And Suggest That Both The Eddy Transport Of De And Transfer Of Energy From Mke To Eke Contribute To The Seasonal Eke Maxima.
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Uroz, L., Yan, Y., Benoit, A., Rabatel, A., Giffard-Roisin, S., & Lin-Kwong-Chon, C. (2024). Using Deep Learning For Glacier Thickness Estimation At A Regional Scale. Ieee Geoscience And Remote Sensing Letters, 212.
Abstract: Mountain Glaciers Play A Critical Role For Mountain Ecosystems And Society With Major Concerns Related To Their Future Evolution And Related Water Resources. Modeling Glacier Future Evolution Allows Anticipating Climate Change Impacts And Informing Policy Decisions. It Relies On Accurate Ice Thickness Estimation At Regional Scales. This Letter Proposes A Deep Learning-Based Approach In A Supervised Learning Framework For Ice Thickness Estimation At A Regional Scale From Surface Ice Velocity Measurements And A Digital Elevation Model (Dem). A Neural Network Model Built Upon A Resnet Architecture Is Proposed Based On The Trade-Off Between The Model Complexity And The Prediction Efficiency. Promising Results Are Obtained From Data Including 1400 Glaciers In The Swiss Alps, Highlighting The Potential Of Deep Learning-Based Approach For Large-Scale Ice Thickness Estimation. The Incorporation Of Expert'S Knowledge Into The Neural Network Model Further Helps Refine The Model Prediction And Improve The Model Relevance. The Ice Volume Difference Between The Reference Issued From Ground Penetrating Radar (Gpr) Measurements And The Predictions By The Proposed Neural Network Model Varies Between 0.5% And 16% Of The Reference Volume. Larger Ice Volume Difference Is Mainly Related To Over-Deepening Of The Bedrock Resulting From Past Larger Extent Of The Glacier, Which Information Is Not Included In The Data.
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Valois, R., Rivière, A., Vouillamoz, J., & Rau, G. (2024). Technical Note: Analytical Solution For Well Water Response To Earth Tides In Leaky Aquifers With Storage And Compressibility In The Aquitard. Hydrology And Earth System Sciences, 282(4), 1041–1054.
Abstract: In Recent Years, There Has Been A Growing Interest In Utilizing The Groundwater Response To Earth Tides As A Means Of Estimating Subsurface Properties. However, Existing Analytical Models Have Been Insufficient In Accurately Capturing Realistic Physical Conditions. This Study Presents A New Analytical Solution To Calculate The Groundwater Response To Earth Tide Strains, Including Storage And Compressibility Of The Aquitard, Borehole Storage, And Skin Effects. We Investigate The Effects Of Aquifer And Aquitard Parameters On The Well Water Response To Earth Tides At Two Dominant Frequencies ( O-1 And M-2 ) And Compare Our Results With Hydraulic Parameters Obtained From A Pumping Test. Inversion Of The Six Hydro-Geomechanical Parameters From Amplitude Response And Phase Shift In Both Semi-Diurnal And Diurnal Tides Provides Relevant Information About Aquifer Transmissivity, Storativity, Well Skin Effect, Aquitard Hydraulic Conductivity, And Diffusivity. The New Model Is Able To Reproduce Previously Unexplained Observations Of The Amplitude And Frequency Responses. We Emphasize The Usefulness In Developing A Relevant Methodology To Use The Groundwater Response To Natural Drivers In Order To Characterize Hydrogeological Systems.
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Védrine, L., Hagenmuller, P., Gélébart, L., Montagnat, M., & Bernard, A. (2024). Role Of Ice Mechanics On Snow Viscoplasticity. Geophysical Research Letters, 515(7).
Abstract: The Porous Structure Of Snow Becomes Denser With Time Under Gravity, Primarily Due To The Creep Of Its Ice Matrix With Viscoplasticity. Despite Investigation Of This Behavior At The Macroscopic Scale, The Driving Microscopic Mechanisms Are Still Not Well Understood. Thanks To High-Performance Computing And Dedicated Solvers, We Modeled Snow Elasto-Viscoplasticity With 3D Images Of Its Microstructure And Different Mechanical Models Of Ice. The Comparison Of Our Numerical Experiments To Oedometric Compression Tests Measured By Tomography Showed That Ice In Snow Rather Behaves As A Heterogeneous Set Of Ice Crystals Than As Homogeneous Polycrystalline Ice. Similarly To Dense Ice, The Basal Slip System Contributed At Most, In The Simulations, To The Total Snow Deformation. However, In The Model, The Deformation Accommodation Between Crystals Was Permitted By The Pore Space And Did Not Require Any Prismatic And Pyramidal Slips, Whereas The Latter Are Pre-Requisite For The Simulation Of Dense Ice. Knowledge Of Snow Settlement Is Essential For Many Applications, Such As Paleoclimatology And Avalanche Forecasting. Snow Densification Is Mainly Driven By Time Dependent And Irreversible Deformations. Simulating This Highly Nonlinear Behavior For Intricate Microstructures Is Time-Consuming, Leading To A Scarcity Of Studies And A Limited Understanding Of The Underlying Microscale Mechanisms. In This Study, We Took Advantage Of An Advanced Numerical Solver To Calculate The Behavior Of 3D Imaged Snow Samples And Compared It With In Situ Experiments. Our Analysis Has Shown That The Crystalline Structure Must Be Taken Into Account, But The Discrepancy Between Experiments And Simulations Suggests The Existence Of Other Mechanisms, Particularly Between Snow Grains. Interestingly, Deformation Mechanisms Other Than Those Required To Simulate Dense Ice Have Been Observed. Ice In Snow Cannot Be Considered As Homogeneous, Individual Crystals Are Shown To Impact Snow Creep The Models Shows That Basal Glide Of A Few Ice Zones Supports Most Of The Snow Deformation In The Simulations, The Contribution Of The Hard Slip Systems Is Negligible, And Deformation Accommodation Is Enabled By The Pore Space
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Wang, Q., Shu, Q., Bozec, A., Chassignet, E., Fogli, P., Fox-Kemper, B., et al. (2024). Impact Of Increased Resolution On Arctic Ocean Simulations In Ocean Model Intercomparison Project Phase 2 (Omip-2). Geoscientific Model Development, 171(1), 347–379.
Abstract: This Study Evaluates The Impact Of Increasing Resolution On Arctic Ocean Simulations Using Five Pairs Of Matched Low- And High-Resolution Models Within The Omip-2 (Ocean Model Intercomparison Project Phase 2) Framework. The Primary Objective Is To Assess Whether A Higher Resolution Can Mitigate Typical Biases In Low-Resolution Models And Improve The Representation Of Key Climate-Relevant Variables. We Reveal That Increasing The Horizontal Resolution Contributes To A Reduction In Biases In Mean Temperature And Salinity And Improves The Simulation Of The Atlantic Water Layer And Its Decadal Warming Events. A Higher Resolution Also Leads To Better Agreement With Observed Surface Mixed-Layer Depth, Cold Halocline Base Depth And Arctic Gateway Transports In The Fram And Davis Straits. However, The Simulation Of The Mean State And Temporal Changes In Arctic Freshwater Content Does Not Show Improvement With Increased Resolution. Not All Models Achieve Improvements For All Analyzed Ocean Variables When Spatial Resolution Is Increased So It Is Crucial To Recognize That Model Numerics And Parameterizations Also Play An Important Role In Faithful Simulations. Overall, A Higher Resolution Shows Promise In Improving The Simulation Of Key Arctic Ocean Features And Processes, But Efforts In Model Development Are Required To Achieve More Accurate Representations Across All Climate-Relevant Variables.
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Zimmer, A., Beach, T., Luzzadder-Beach, S., Rabatel, A., Encarnación, R., Robles, J., et al. (2024). Soil Temperature And Local Initial Conditions Drive Carbon And Nitrogen Build-Up In Young Proglacial Soils In The Tropical Andes And European Alps. Catena, 2352.
Abstract: Climate Warming Has Accelerated The Retreat Of Mountain Glaciers Worldwide, Exposing New Areas To Weathering, Vegetation Colonization, And Soil Formation. In Light Of Probable Climate Changes Such As Warming And New Extremes, Understanding The Factors That Control Soil Organic Carbon (Soc) And Nitrogen Build-Up Is Crucial To Comprehend Proglacial Soils And Ecosystem Formation. To This End, We Examine The Evolution Of Soc, Nitrogen (Total N And Nh4+), And Phosphorus (Available P) Along Nine 120-Year Chronosequences Of Deglacierization Distributed Between The European Alps And Tropical Andes. Our Dataset Includes Geochemical Analyses Of 188 Soil Samples, In Situ Soil Temperature Data For The Period 2019-2022, And Hydrographic Variables. Although Time Controls Proglacial Soil Development At All Sites, Our Study Highlights Distinct Pedogenesis Dynamics Between Proglacial Landscapes Depending On The Micro And Macro Environmental Context. Differences In Soil Development Were Strongly Driven By Growing Degree Days (Gdd), Maximum Soil Temperature, And Parent Material. Notably, We Identified A Positive Effect Of Gdd On Soc And N (Total N And Nh4+), While Our Results Indicate A Negative Effect Of Maximum Soil Temperature On Soc And Nh4+, Suggesting That Overly High Temperatures Reduce Microbial Mineralization And Organic Matter Input To The Soil Matrix. We Reported The Presence Of Higher Initial Soc, Total N, And Nh4+ In The Andean Sites Than In The Alps Sites, Suggesting Enhanced Soil Development At The Andean Locations. This Comparative Study Suggests The Relative Importance Of Maximum Temperature And Initial Site Conditions (E.G., Parent Materials, Glacier Biomes) During Proglacial Pedogenesis. Our Findings Highlight That Soil Temperature Modulates Pedogenesis In A Complex Way And Suggest Avoiding Simply Associating Greater Soil Development With Higher Soil Temperature In Proglacial Landscapes.
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Zimmer, A., Beach, T., Luzzadder-Beach, S., Rabatel, A., Robles, J., Encarnaci, R., et al. (2024). Physico-Chemical Properties And Toxicity Of Young Proglacial Soils In The Tropical Andes And Alps. Catena, 2372.
Abstract: New Soils Formed After Glacier Retreat Can Provide Insights Into The Rates Of Soil Formation In The Context Of Accelerated Warming Due To Climate Change. Recently Deglacierized Terrains (Since The Little Ice Age) Are Subject To Weathering And Pedogenesis, And Freshly Exposed Sediments Are Prone To React Readily With The Environment. This Study Aims To Determine The Impact Of Parent Material And Time On Soil Physical And Chemical Properties Of Nine Proglacial Landscapes Distributed In The Tropical Andes And Alps. A Total Of 188 Soil Samples Were Collected Along Chronosequences Of Deglacierization And From Sites That Differed In Terms Of Parent Material And Classified Following Three Parent Material Groups: (1) Granodiorite-Tonalite (Gt), (2) Gneiss-Shales-Schists (Gss), And (3) Mont-Blanc Granite (Mbg). We Determined Physical And Chemical Soil Properties Such As Contents Of Clay, Silt, Sand, Organic Carbon, Bulk Density (Bd), Ph, Extractable Cation (Exca, Exmg, Exk), Elemental Composition By Xray Fluorescence (Al, Si, P, S, K, Ca, Mn, Fe, Cu, Zn, As, Mo, Hg, Pb) And Icp-Ms (Al, Ca, Cu, Fe, K, Mg, Mn, Mo, Na, P, S, Zn), And Mineral Phase (Xrd Diffraction Analysis). Parent Material-Controlled Particle-Size Distribution, Soc, Ph, Available P, Exca, And Exmg, Whereas Time Since Deglacierization Only Affected Soc And P, And Exmg Globally. Most Of The Significant Differences In Soil Properties Between Parent Material Groups Occurred Within The First 17 Years After Deglacierization, And Then We Observed A Homogenization Between Sites. While The Higher Soc And P Contents Observed Within The Gt Andean Sites Might Be Due To The Parent Material Composition Leading To Faster Initial Soil Formation, We Identified Potential As, Cu, Mo, And Mn Toxicity Within Those Soils. Our Study Highlights The Need To Investigate Further Proglacial Soil'S Buffering Capacity And Carbon Sequestration To Globally Inform The Conservation And Management Of Novel Proglacial Ecosystems.
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2023 |
Acary, V., Bourrier, F., & Viano, B. (2023). Variational Approach For Nonsmooth Elasto-Plastic Dynamics With Contact And Impacts. Computer Methods In Applied Mechanics And Engineering, .
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Agudelo, J., Espinoza, J., Junquas, C., Arias, P., Sierra, J., & Olmo, M. (2023). Future Projections Of Low-Level Atmospheric Circulation Patterns Over South Tropical South America: Impacts On Precipitation And Amazon Dry Season Length. Journal Of Geophysical Research-Atmospheres, 1281(222).
Abstract: The Last Few Decades Have Shown Evidence Of A Lengthening Dry Season In Southern Amazonia, Which Is Associated With A Delay In The Onset Of The South American Monsoon System (Sams). Using A Pattern Recognition Framework Of Atmospheric Circulation Patterns (Cps), Previous Studies Have Identified Specific Atmospheric Situations Related To The Onset Of The Sams. Here, We Analyze The Future Changes In The Cps That Largely Define The Main Hydro-Climatological States Of Tropical South America. We Evaluated The Cp Changes That Occurred Between Two Periods: Historical (1970-2000) And Future (2040-2070), Using Six General Circulation Models (Gcms) From The Coupled Model Intercomparison Project Phase 6. Future Gcm Projections Show Significant Spatio-Temporal Changes In The Cps Associated With The Dry Season In Southern Amazonia During The Mid-21St Century. These Changes Are Related To Both A Late Onset Of The Sams And An Early Demise Of The Sams. Particularly, The Cp Methodology Allowed For A Better Understanding Of The Behavior Of The Southern Amazon Dry Season Under Future Conditions, Showing An Increase In The Frequency Of The Cps Typically Observed During The Dry Season. The Occurrence Of Dry Days In The Amazon Basin During The Austral Winter Of The Mid-21St Century Increases By 19.4% On Average, With Respect To The Historical Period. This Methodology Also Identified A Future Increase In The Frequency Of Dry Cps, Both At The Beginning Of The Dry-To-Wet Transition Period (8%) And At The End Of The Wet-To-Dry Transition Season (11%).
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Ahmed, S., Thomas, J., Angot, H., Dommergue, A., Archer, S., Bariteau, L., et al. (2023). Modelling The Coupled Mercury-Halogen-Ozone Cycle In The Central Arctic During Spring. Elementa-Science Of The Anthropocene, .
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Aidara, M., Fam, P., Danso, D., Mortey, E., Mbaye, A., Ndiaye, M., et al. (2023). Contribution To The Building Of A Weather Information Service For Solar Panel Cleaning Operations At Diass Plant (Senegal, Western Sahel). Open Geosciences, 151(1).
Abstract: The Accumulation Of Dust On The Surface Of Solar Panels Reduces The Amount Of Sunlight Reaching The Solar Cells And Results In A Decrease In Panel Performance. To Avoid This Loss Of Production And Thus, To Improve The Performance Capacity, Solar Panels Must Be Cleaned Frequently. The West African Region Is Well Known For Its High Solar Energy Potential. However, This Potential Can Be Reduced By The High Occurrence Of Dust Storms During The Year. This Article Aims To Provide A Contribution To The Construction Of A Meteorological Information Service For Solar Panel Cleaning Operations At Diass Solar Plant In Senegal (Western Sahel). It Is Based On A Full Year In Situ Experiment Comparing The Power Loss Due To Dust Between Solar Panels Cleaned At Different Frequencies And Those Not Cleaned. The Model To Determine The Cleaning Frequencies Is Based On The Deposition Rate Of Airborne Particles, The Concentration Of Airborne Particles, And The Density Of The Dust That Has A Major Impact On The Power Loss. Cleaning Frequencies Are Presented At Seasonal Scale Because In The Study Area, Dust Episodes Differ According To The Seasons. A Cost-Benefit Analysis Is Also Performed To Demonstrate The Advantage Of Using Weather Information Service To Support The Dust Cleaning Operations At Diass Plant. As Results, It Is Found That Cleaning Every 3 Weeks Is Required During The Dry Seasons, December-January-February And March-April-May. During The Rainy Season, Cleaning Every 5 Weeks Is Recommended In June-July-August, While In September-October-November Cleaning Every 4 Weeks Is Sufficient To Maintain An Optimal Performance Of The Solar Panel. The Total Costs Of Cleaning Operations Based On These Results Are Reduced Compared To The Current Costs Of Cleaning And The Benefits Are Much Higher Than Without Cleaning Action.
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Al-Yaari, A., Condom, T., Junquas, C., Rabatel, A., Ramseyer, V., Sicart, J., et al. (2023). Climate Variability And Glacier Evolution At Selected Sites Across The World: Past Trends And Future Projections. Earths Future, 111(101).
Abstract: The Availability Of Freshwater From Glaciers And Snowmelt Is Of Vital Importance For People And Ecosystems In The Context Of Global Climate Change. Here, We Focus On 25 Glaciers Located In Different Climates And Latitudes And Investigate Their Recent (1958-2020) And Future Projected Trends (2020-2050 And 2070-2100) In Monthly Precipitation (Pr), Maximum And Minimum Temperatures, Ice Mass Loss, And Their Relationships With Cloud Properties. The Study Sites Are Located In Temperate Europe (France), The Inner (Ecuador, Venezuela, And Colombia) And Outer Tropics (Bolivia And Peru), Central America (Mexico), Tropical Southeast Asia (Indonesia), Equatorial Africa (Uganda), And The Southern Dry And Patagonian Andes (Chile And Argentina). The Climate Analyses Are Based On Terraclimate Data (Monthly Climate And Climatic Water Balance For Global Terrestrial Surfaces) And 28 Cordex (Coordinated Regional Climate Downscaling Experiment) Climate Simulations. Our Findings Reveal That, Extrapolating Current Glacier Volume Change Trends, Almost Half Of The Studied Glaciers Are Likely To Vanish (95%-100% Volume Loss) By 2050, With Widespread Warming And Drying Trends Since 1958. A Shift Toward Wetter Conditions At Pico Humboldt (Venezuela) And Martial Este (Argentina) Identifiable In The Cordex Simulation Will Very Likely Not Have A Limiting Impact On Glacier Mass Loss Owing To Increasing Temperatures, Which Will Raise The Elevation Of The Rain/Snow Limit. Our Results Provide Useful New Information To Better Understand Glacier-Climate Relationships And Future Scenarios Dominated By Ice Mass Loss Trends Across The Globe. These Findings Suggest Serious Consequences For Future Water Availability, Which Exacerbate The Vulnerability Of Local Populations And Ecosystems.
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Al-Yaari, A., Zhao, Y., Cheruy, F., & Thiery, W. (2023). Heatwave Characteristics In The Recent Climate And At Different Global Warming Levels: A Multimodel Analysis At The Global Scale. Earths Future, 111(9).
Abstract: The Representation Of Heatwaves (Hws) In The Coupled Model Intercomparison Project Phase 6 (Cmip6) Models Is Analyzed. This Study (A) Evaluates The Performance Of Cmip6 Simulations Against Global Reanalysis And Observations Regarding Time- And Intensity-Related Criteria And (B) Investigates How Hws Are Projected To Change At Different Global Warming Levels (Gwls). During 1979-2014, The Dispersion Of The Models Is Comparable To The Observational Uncertainty For The Time Indices (Duration, Frequency, Number Of Events). It Is Of The Order Of One Event Per Year, 1 Day For The Duration Of The Events And 2 Days For The Frequency, With Tendencies For Over- Or Underestimation, Depending On The Reference Data Set And The Region Considered. For The Hw Magnitude, The Models ' Dispersion Can Reach 15 Degrees C For A Given Region And Is Significantly Higher Than The Observational Uncertainty. The Mean Intensity Of Hws Tends To Be Overestimated, Which Is Partly Attributed To Overly Pronounced Drying Of The Soil During Hw Events. The Contribution Of The Soil Moisture Anomaly To The Temperature Anomaly During Recent Specific Hws Is Shown To Reach Up To 30% Of The Signal. For A Given Gwl, Intensification Of Hw Occurrence, Spatial Extension, And Duration Is Detected Worldwide, But It Is Modulated At The Regional Scale And Strongly Model Dependent. For Time-Related Indices, Tropical Regions And The Arabian Peninsula Will Be Most Impacted, But The Maximum Temperature Will Strongly Increase In Mid-Latitude Regions. Time-Space Analyses Of The Evolution Of Hw Properties For A Given Gwl Are Discussed. Plain Language Summary In This Study, We Evaluate The Number Of Heatwaves (Hws) Occurrences (Hwn), The Duration Of The Longest Event (Hwd), The Frequency Of Hw Days (Hwf), The Near-Surface Maximum Temperature For Hw Days (Hwm), And The Day With The Hottest Events (Hwa) Simulated By Coupled Model Intercomparison Project Phase 6 (Cmip6) Models Against Observations And Reanalysis Over 1979-2014, And Their Projections. The Cmip6 Models Overestimate Hwn And Hwf In The Mediterranean, Central Russia, Northeast Asia, And Southeast China Against Observations. All Considered Cmip6 Models Overestimate Hwd In The Mediterranean And Southeast Chinese Regions Against Hadghcnd Observations, But The Estimates Fell Within The Range Of Observations For All Other Regions. Many Models Overestimate Hwm Against Both Observations And Reanalysis. A Global Warming Of 3 Degrees C Above Preindustrial Levels Will Significantly Increase Hwn By Over Four Events Per Year In Most Regions Except Amazonia And The Arabian Peninsula. The Longest Hw Event Is Projected To Increase By 20-30 Days Under 3 Degrees C Of Global Warming Across Amazonia, The Middle East, And Parts Of Africa. Excessive Drying Is Detected In The Recent Climate Simulated Hw'S Days, Which Might Impact The Strength Of The Response Of The Simulated Hws To Global Warming, And The Characteristics Of Future Droughts.
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Alonso-Gonzalez, E., Gascoin, S., Arioli, S., & Picard, G. (2023). Exploring The Potential Of Thermal Infrared Remote Sensing To Improve Asnowpack Model Through An Observing System Simulation Experiment. Cryosphere, 171(8), 3329–3342.
Abstract: The Assimilation Of Data From Earth Observation Satellites Into Numerical Models Is Considered To Be The Path Forward To Estimate Snow Cover Distribution In Mountain Catchments, Providing Accurate Information On The Mountainous Snow Water Equivalent (Swe). The Land Surface Temperature (Lst) Can Be Observed From Space, But Its Potential To Improve Swe Simulations Remains Underexplored. This Is Likely Due To The Insufficient Temporal Or Spatial Resolution Offered By The Current Thermal Infrared (Tir) Missions. However, Three Planned Missions Will Provide Global-Scale Tir Data At Much Higher Spatiotemporal Resolution In The Coming Years.To Investigate The Value Of Tir Data To Improve Swe Estimation, We Developed A Synthetic Data Assimilation (Da) Experiment At Five Snow-Dominated Sites Covering A Latitudinal Gradient In The Northern Hemisphere. We Generated Synthetic True Lst And Swe Series By Forcing An Energy Balance Snowpack Model With The Era5-Land Reanalysis. We Used This Synthetic True Lst To Recover The Synthetic True Swe From A Degraded Version Of Era5-Land. We Defined Different Observation Scenarios To Emulate The Revisiting Times Of Landsat 8 (16 D) And The Thermal Infrared Imaging Satellite For High-Resolution Natural Resource Assessment (Trishna) (3 D) While Accounting For Cloud Cover. We Replicated The Experiments 100 Times At Each Experimental Site To Assess The Robustness Of The Assimilation Process With Respect To Cloud Cover Under Both Revisiting Scenarios. We Performed The Assimilation Using Two Different Approaches: A Sequential Scheme (Particle Filter) And A Smoother (Particle Batch Smoother).The Results Show That Lst Da Using The Smoother Reduced The Normalized Root Mean Square Error (Nrmse) Of The Swe Simulations From 61 % (Open Loop) To 17 % And 13 % For 16 D Revisit And 3 D Revisit Respectively In The Absence Of Clouds. We Found Similar But Higher Nrmse Values By Removing Observations Due To Cloud Cover But With A Substantial Increase In The Standard Deviation Of The Nrmse Of The Replicates, Highlighting The Importance Of Revisiting Times In The Stability Of The Assimilation Performance. The Smoother Largely Outperformed The Particle Filter Algorithm, Suggesting That The Capability Of A Smoother To Propagate The Information Along The Season Is Key To Exploit Lst Information For Snow Modelling. Finally, We Have Compared The Benefit Of Assimilating Lst With Synthetic Observations Of Fractional Snow Cover Area (Fsca). Lst Da Performed Better Than Fsca Da In All The Study Sites, Suggesting That The Information Provided By Lst Is Not Limited To The Duration Of The Snow Season. These Results Suggest That The Lst Data Assimilation Has An Underappreciated Potential To Improve Snowpack Simulations And Highlight The Value Of Upcoming Tir Missions To Advance Snow Hydrology.
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Ancey, C., & Recking, A. (2023). Scaling Behavior Of Bedload Transport: What If Bagnold Was Right? Earth-Science Reviews, 2462.
Abstract: There Is A Paradox In The Relationship Between Bedload Transport Rates And Flow Variables: Laboratory And Field Studies Have Reported On How Bedload Transport Rates Depend On Flow Variables Through A Power Law, But None Of The Empirical Laws Fitted To The Data Has Managed To Provide Accurate Predictions Of Bedload Transport Over A Wide Range Of Flow Conditions. Inferring Bedload Transport'S Scaling Behavior From Data Has Remained A Stubborn Problem Because The Data Are Very Noisy. It Is, Therefore, Difficult To Progress On This Problem Without Some Informed Speculation About How Bedload And Flow Interact. Ralph Bagnold Proposed An Original Theory To Resolve This Problem. This Paper Reviews And Updates Bagnold'S Model By Separating The Effects Of Flow Resistance And Efficiency (Energy Transfer From Water To Bedload) On Dimensionless Transport Rates Phi. Both Variables' Contributions To Transport Rates Can Be Parameterized Separately For The Three Transport Regimes That Bagnold Defined (No Transport, Transitional, And Sheet Flow). We Also Consider Two Possible Control Variables: The Dimensionless Shield Stress Tau* And A Dimensionless Number Related To Stream Power. In The Transitional Regime, The Dimensionless Bedload Transport Rate Scales As Phi Proportional To Tau*3, Whereas In The Sheet-Flow Regime, It Varies As Phi Proportional To Tau*5/3. We End Up With Two Bagnold Equations: One Based On Physical Principles And Involving Shields Stress Tau*, Flow Resistance F, A Density Ratio, And A Bed Slope; The Other Based On Non-Linear Regression And Stream Power. Compared To A Large Set Of Laboratory And Field Data, Predictions From Bagnold'S Model Show Reasonable Accuracy When The Bed Is Plane.
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Arik, A., Chionne, D., Renou, Y., Brochet, A., Blanchet, J., Kharbouche, M., et al. (2023). The Limits Of Scalability: Uncovering Friction Between Levels Of Flood Risk Governance In The French Alps. International Journal Of Disaster Risk Reduction, 979.
Abstract: Flood Risk Governance Can Be A Source Of Tension Between Different Government Actors And Citizens Across Spatial Scales. In This Context, We Consider The Hydro-Social Contract (Hsc) As A Framework To Understand The Formal And Informal Societal Constructs That Aid Or Impede Effectiveness In Managing Flood Risk. Specifically, We Used Q-Methodology To Understand Different Perspectives Of Flood Risk Governance And Identify Points Of Friction In Executing The Hsc. We Interviewed 62 Flood Risk Management Actors From Small Municipalities (Intra-Watershed) To Regional State Agencies (Inter-Basin) In The Isere River Basin Of France, From Which Three Perspectives Emerged. Most Participants Correlated To A Perspective Reaffirming A Commitment To Integrated And Holistic Approaches In Flood Risk Management. However, The Second And Third Perspectives Illustrate A Governance Gap Due To An Upward Transfer Of Risk Management Responsibilities To A Broader Watershed Approach. At The Same Time, Municipalities Remain Responsible For Crisis Management In The Advent Of Flooding. Our Findings Bring Into Question The Right Balance Of Scale In Flood Risk Governance, Particularly Regarding Hydrological Boundaries That Are Incongruous With Political Jurisdictions At Multiple Scales.
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Arioli, S., Picard, G., Arnaud, L., & Favier, V. (2023). Dynamics Of The Snow Grain Size In A Windy Coastal Area Of Antarctica From Continuous In Situ Spectral-Albedo Measurements. Cryosphere, , 232322–234222.
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Autin, P., Sicart, J., Rabatel, A., Hock, R., & Jomelli, V. (2023). Climate Reconstruction Of The Little Ice Age Maximum Extent Of The Tropical Zongo Glacier Using A Distributed Energy Balancemodel. Comptes Rendus Geoscience, 3553, 381–398.
Abstract: This Study Assessed The Climate Conditions That Caused The Tropical Zongo Glacier (16 Degrees S, Bolivia) To Reach Its Little Ice Age (Lia) Maximum Extent In The Late 17Th Century. We Carried Out Sensitivity Analyses Of The Annual Surface Mass Balance To Different Physically Coherent Climate Scenarios Constrained By Information Taken From Paleoclimate Proxies And Sensitivity Studies Of Past Glacier Advances. These Scenarios Were Constrained By A 1.1 K Cooling And A 20% Increase In Annual Precipitation Compared To The Current Climate. Seasonal Precipitation Changes Were Constructed Using Shuffled Input Data For The Model: Measurements Of Air Temperature And Relative Humidity, Precipitation, Wind Speed, Incoming Short And Longwave Radiation Fluxes, And Assessed Using A Distributed Energy Balance Model. They Were Considered Plausible If Conditions Close To Equilibrium Glacier-Wide Mass Balance Were Obtained. Results Suggest That On Top Of A 1.1 K Cooling And Similar To 20% Increase In Annual Precipitation, Only Two Seasonal Precipitation Patterns Allow Lia Equilibrium: Evenly Distributed Precipitation Events Across The Year And An Early Wet Season Onset.
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Bade, R., Rousis, N., Adhikari, S., Baduel, C., Bijlsma, L., Bizani, E., et al. (2023). Three Years Of Wastewater Surveillance For New Psychoactive Substances From 16 Countries. Water Research X, 191.
Abstract: The Proliferation Of New Psychoactive Substances (Nps) Over Recent Years Has Made Their Surveillance Complex. The Analysis Of Raw Municipal Influent Wastewater Can Allow A Broader Insight Into Community Consumption Patterns Of Nps. This Study Examines Data From An International Wastewater Surveillance Program That Collected And Analysed Influent Wastewater Samples From Up To 47 Sites In 16 Countries Between 2019 And 2022. Influent Wastewater Samples Were Collected Over The New Year Period And Analysed Using Validated Liquid Chromatog-Raphy – Mass Spectrometry Methods. Over The Three Years, A Total Of 18 Nps Were Found In At Least One Site. Synthetic Cathinones Were The Most Found Class Followed By Phenethylamines And Designer Benzodiazepines. Furthermore, Two Ketamine Analogues, One Plant Based Nps (Mitragynine) And Methiopropamine Were Also Quantified Across The Three Years. This Work Demonstrates That Nps Are Used Across Different Continents And Countries With The Use Of Some More Evident In Particular Regions. For Example, Mitragynine Has Highest Mass Loads In Sites In The United States, While Eutylone And 3-Methylmethcathinone Increased Considerably In New Zealand And In Several European Countries, Respectively. Moreover, 2F-Deschloroketamine, An Analogue Of Ke-Tamine, Has Emerged More Recently And Could Be Quantified In Several Sites, Including One In China, Where It Is Considered As One Of The Drugs Of Most Concern. Finally, Some Nps Were Detected In Specific Regions During The Initial Sampling Campaigns And Spread To Additional Sites By The Third Campaign. Hence, Wastewater Surveillance Can Provide An Insight Into Temporal And Spatial Trends Of Nps Use.
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Banwell, A., Wever, N., Dunmire, D., & Picard, G. (2023). Quantifying Antarctic-Wide Ice-Shelf Surface Melt Volume Using Microwave And Firn Model Data: 1980 To 2021. Geophysical Research Letters, .
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Barten, J., Ganzeveld, L., Steeneveld, G., Blomquist, B., Angot, H., Archer, S., et al. (2023). Low Ozone Dry Deposition Rates To Sea Ice During The Mosaic Field Campaign: Implications For The Arctic Boundary Layer Ozone Budget. Elementa-Science Of The Anthropocene, .
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Bayle, A., Carlson, B., Zimmer, A., Vallee, S., Rabatel, A., Cremonese, E., et al. (2023). Local Environmental Context Drives Heterogeneity Of Early Succession Dynamics In Alpine Glacier Forefields. Biogeosciences, , 164911–166911.
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Bekaert, D., Blard, P., Raoult, Y., Pik, R., Kipfer, R., Seltzer, A., et al. (2023). Last Glacial Maximum Cooling Of 9 Degrees C In Continental Europe From A 40 Kyr-Long Noble Gas Paleothermometry Record. Quaternary Science Reviews, .
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Belmajdoub, H., El Aouni, A., & Minaoui, K. (2023). Convolutional Neural Networks For Coastal Upwelling Monitoring Along The Atlantic Coast Of Morocco. Remote Sensing Letters, , 77577–78577.
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Belmajdoub, H., Minaoui, K., El Aouni, A., Hilmi, K., Saadane, R., & Chehri, A. (2023). A New Upwelling Index For The Moroccan Atlantic Coast For The Period Between 1982-2021. Remote Sensing, .
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Bendinger, A., Cravatte, S., Gourdeau, L., Brodeau, L., Albert, A., Tchilibou, M., et al. (2023). Regional Modeling Of Internal-Tide Dynamics Around New Caledonia – Part 1: Coherent Internal-Tide Characteristics And Sea Surface Height Signature. Ocean Science, 191(4), 1315–1338.
Abstract: The Southwestern Tropical Pacific Exhibits A Complex Bathymetry And Represents A Hot Spot Of Internal-Tide Generation. Based On A Tailored High-Resolution Regional Model, We Investigate For The First Time The Internal-Tide Field Around The New Caledonia Islands Through Energy Budgets That Quantify The Coherent Internal-Tide Generation, Propagation, And Dissipation. A Total Of 15.27 Gw Is Converted From The Barotropic To The Baroclinic M2 Tide With The Main Conversion Sites Associated With The Most Prominent Bathymetric Structures Such As Continental Slopes And Narrow Passages In The North (2.17 Gw) And Ridges And Seamounts South Of New Caledonia (3.92 Gw). The Bulk Of Baroclinic Energy Is Generated In Shallow Waters Around 500 M Depth And On Critical To Supercritical Slopes, Highlighting The Limitations Of Linear Semi-Analytical Models In Those Areas. Despite The Strongly Dominant Mode-1 Generation, More Than 50 % Of The Locally Generated Energy Either Dissipates In The Near Field Close To The Generation Sites Or Loses Coherence. The Remaining Baroclinic Energy Propagates Within Well-Defined Tidal Beams With Baroclinic Energy Fluxes Of Up To 30 Kw M – 1 Toward The Open Ocean. The New Caledonia Site Represents A Challenge For Swot (Surface Water And Ocean Topography) Observability Of Balanced Motion In The Presence Of Internal Tides With Sea Surface Height (Ssh) Signatures > 6 Cm At Similar Wavelengths. We Show For Our Study Region That A Correction Of Ssh For The Coherent Internal Tide Potentially Increases The Observability Of Balanced Motion From Wavelengths > 160 Km To Well Below 100 Km.
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Berthier, E., Floriciou, D., Gardner, A., Gourmelen, N., Jakob, L., Paul, F., et al. (2023). Measuring Glacier Mass Changes From Space-A Review. Reports On Progress In Physics, 868(3).
Abstract: Glaciers Distinct From The Greenland And Antarctic Ice Sheets Are Currently Losing Mass Rapidly With Direct And Severe Impacts On The Habitability Of Some Regions On Earth As Glacier Meltwater Contributes To Sea-Level Rise And Alters Regional Water Resources In Arid Regions. In This Review, We Present The Different Techniques Developed During The Last Two Decades To Measure Glacier Mass Change From Space: Digital Elevation Model (Dem) Differencing From Stereo-Imagery And Synthetic Aperture Radar Interferometry, Laser And Radar Altimetry And Space Gravimetry. We Illustrate Their Respective Strengths And Weaknesses To Survey The Mass Change Of A Large Arctic Ice Body, The Vatnajokull Ice Cap (Iceland) And For The Steep Glaciers Of The Everest Area (Himalaya). For Entire Regions, Mass Change Estimates Sometimes Disagree When A Similar Technique Is Applied By Different Research Groups. At Global Scale, These Discrepancies Result In Mass Change Estimates Varying By 20%-30%. Our Review Confirms The Need For More Thorough Inter-Comparison Studies To Understand The Origin Of These Differences And To Better Constrain Regional To Global Glacier Mass Changes And, Ultimately, Past And Future Glacier Contribution To Sea-Level Rise.
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Berthier, E., Vincent, C., & Six, D. (2023). Exceptional Thinning Through The Entire Altitudinal Range Of Mont-Blanc Glaciers During The 2021/22 Mass Balance Year. Journal Of Glaciology, .
Abstract: Widespread Glacier Losses Have Been Observed In Most Glaciated Regions On Earth During Recent Decades, With A Typical Pattern Of Strong Thinning In Their Lower Reaches And Limited Elevation Changes In Their Accumulation Areas. Here, We Use Pleiades Satellite Stereo-Images Of The Mont-Blanc Massif (Alps) To Reveal That Thinning Took Place Through The Entire Elevation Range During The Exceptional 2021/22 Mass-Balance Year. Above 3000 M A.S.L. On Argentiere Glacier And Mer De Glace, Thinning Rates Exceeded 3.5 M A-1 While Almost No Change Occurred During The Previous 9 Years. Below 3000 M A.S.L., These Anomalous Thinning Rates Are Essentially Explained By Changes In Surface Mass Balance. At Higher Altitudes, Other Processes Such As Firn Densification May Play A Role. Our Analysis Shows That High Altitude Glaciers, Mostly Stable During The Last 100 Years, Are Now Responding To The Impact Of Climate Change.
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Blanchet, J., Blanc, A., Boulard, J., & Creutin, J. (2023). Will Future Southwestern Europe Large-Scale Circulations Resemble Past Circulations? A Focus On The Circulations Driving Extreme Precipitation In The Northern French Alps. Journal Of Geophysical Research-Atmospheres, .
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Bodjrenou, R., Cohard, J., Hector, B., Lawin, E., Chagnaud, G., Danso, D., et al. (2023). Evaluation Of Reanalysis Estimates Of Precipitation, Radiation, And Temperature Over Benin (West Africa). Journal Of Applied Meteorology And Climatology, 626(8), 1005–1022.
Abstract: In West Africa, Climatic Data Issues, Especially Availability And Quality, Remain A Significant Constraint To The Development And Application Of Distributed Hydrological Modeling. As Alternatives To Ground-Based Observations, Reanaly-Sis Products Have Received Increasing Attention In Recent Years. This Study Aims To Evaluate Three Reanalysis Products, Namely, Era5, Water And Global Change (Watch) Forcing Data (Wfd) Era5 (Wfde5), And Merra-2, From 1981 To 2019 To Determine Their Ability To Represent Four Hydrological Climates Variables Over A Range Of Space And Time Scales In Benin. The Variables From The Reanalysis Products Are Compared With Point Station Databased Metrics Kling-Gupta Effi- Ciency (Kge), Mean Absolute Error (Mae), Correlation, And Relative Error In Precipitation Annual (Repa). The Results Show That Era5 Presents A Better Correlation For Annual Mean Temperature (Between 0.74 And 0.90) Than Do Wfde5 (0.63-0.78) And Merra-2 (0.25-0.65). Both Era5 And Wfde5 Are Able To Reproduce The Observed Upward Trend Of Tem-Perature (0.2 & Deg;C Decade -1) In The Region. We Noted A Systematic Cold Bias Of -1.3 & Deg;C In All Reanalyses Except Wfde5 (-0.1 & Deg;C). On The Monthly Time Scale, The Temperature Of The Region Is Better Reproduced By Era5 And Wfde5 (Kge & Ge; 0.80) Than By Merra-2 (Kge , 0.5). At All Time Scales, Wfde5 Produces The Best Mae Scores For Longwave (Lw) And Shortwave (Sw) Radiation, Followed By Era5. Wfde5 Also Provides The Best Estimates For The Annual Precipitation (Repa 2 ]-25, 25[ And Kge & Ge; 50% At Most Stations). Era5 Produces Similar Results, But Merra-2 Performs Poorly In All The Metrics. In Addition, Era5 And Wfde5 Reproduce The Bimodal Rainfall Regime In Southern Benin, Unlike Merra-2, But All Products Have Too Many Small Rainfall Events.
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Bonneau, J., Branger, F., Castebrunet, H., & Kouyi, G. (2023). The Impact Of Stormwater Management Strategies On The Flow Regime Of A Peri-Urban Catchment Facing Urbanisation And Climate Change: A Distributed Modelling Study In Lyon, France. Urban Water Journal, .
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Borbon, A., Dominutti, P., Panopoulou, A., Gros, V., Sauvage, S., Farhat, M., et al. (2023). Ubiquity Of Anthropogenic Terpenoids In Cities Worldwide: Emission Ratios, Emission Quantification And Implications For Urban Atmospheric Chemistry. Journal Of Geophysical Research-Atmospheres, 1281(7).
Abstract: Terpenoids (Isoprene And Monoterpenes) Are Highly Reactive Volatile Organic Compounds (Vocs) Known For Decades For Their Biogenic Origin. Here, We Discuss The Nature And Magnitude Of Their Anthropogenic Emissions. We Compiled And Re-Analyzed 14 Data Sets Of In Situ Voc Observations Collected Over The Last Decade In Contrasting Urban Areas From Mid-Latitudes To Subtropical Regions. We Show The Systematic Presence Of Anthropogenic Terpenoids In Urban Ambient Air With Clear Covariations With Anthropogenic Compounds (R-2 > 0.50) Even During Mid-Latitude Winters. Despite The Emerging Importance Of Monoterpene Emissions From Consumer Products In North American Cities, There Is Some Evidence Of Monoterpene Emissions From Tailpipe Exhaust In Cities Of The Developing World. The Traffic-Related Fraction Of Monoterpenes Is Estimated And Can Account For Up To 40% Of Their Ambient Levels. The Anthropogenic Emission Ratios (Er) Of Some Terpenoids (Isoprene, A-Pinene And Limonene) Are Estimated And Spatially Compared. The Anthropogenic Emissions Of Terpenoids Are Indirectly Estimated From Those Er Combined To Regional And Global Emission Inventories (Cams-Glob-Ant_V4.2) At Urban And Country Scale Focusing On France, Lebanon, And Vietnam. Those Anthropogenic Emissions Do Not Represent More Than 3% Of Other Anthropogenic Voc Emissions. However, They Dominate By One To Three Orders Of Magnitude The Reactivity Of Other Anthropogenic Vocs Regarding No3 Oxidation And Ozonolysis. This Study Raises Two Questions Which Need Further Investigations In The Future: (A) The Significance Of Terpenoid Emissions From Traffic, Especially In Urban Areas Of The Developing World And (B) The Role Of Anthropogenic Terpenoids In Nighttime And Wintertime Atmospheric Chemistry At Mid-Latitudes.
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Borbon, A., Dominutti, P., Panopoulou, A., Gros, V., Sauvage, S., Farhat, M., et al. (2023). Ubiquity Of Anthropogenic Terpenoids In Cities Worldwide: Emission Ratios, Emission Quantification And Implications For Urban Atmospheric Chemistry. Journal Of Geophysical Research-Atmospheres, .
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Borlaza, L., Thuy, V., Grange, S., Socquet, S., Moussu, E., Mary, G., et al. (2023). Impact Of Covid-19 Lockdown On Particulate Matter Oxidative Potential At Urban Background Versus Traffic Sites. Environmental Science-Atmospheres, .
Abstract: In Europe, Covid-19 Lockdown Restrictions Were First Implemented In March 2020 To Control The Spread Of The Disease From The Sars-Cov-2 Virus. Many Studies Have Focused On The Influence Of The Applied Measures On Pollution Levels During This Period, But Very Limited Information On The Oxidative Potential (Op), An Emerging Metric Of Particulate Matter (Pm) Exposure. Furthermore, Most Previous Studies Also Commonly Used Comparative Methods With Historical Datasets, Which May Not Be Estimating The Real Pollution Levels Without The Lockdown Restrictions In Place. In This Study, The Op Of Pm Collected At Urban Background (Grenoble, France) And Traffic (Bern, Switzerland) Sites Was Assessed Using Dithiothreitol (Dtt) And Ascorbic Acid (Aa) Assays. These Measurements Were Also Compared With Pm And Black Carbon (Bc) Mass Concentrations, Including The Wood Burning And Fossil Fuel Fractions Of Bc. To Obtain A More Realistic Pollution Level, Assuming There Were No Lockdown Restrictions In Place, A Machine Learning Technique Called The Random Forest (Rf) Regression Model Was Applied To Predict A Business-As-Usual (Bau) Level For Op, Pm, And Bc In Both Sites. This Model Provided A Good Estimate Of The Bau Levels, Allowing A More Realistic Assessment Of The Pollution Changes During The Lockdown Period. The Results Indicate A Clear Decrease In Op Found In The Traffic Site, While A More Modest Change In Op Was Found At The Urban Background Site, Likely Due To Sustained Contributions From Wood Burning Sources For Residential Heating. Overall, This Study Confirms The Major Roles Of Both Of These Combustion Sources In The Op Levels In Ambient Air.
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Bouchet, M., Landais, A., Grisart, A., Parrenin, F., Prié, F., Jacob, R., et al. (2023). The Antarctic Ice Core Chronology 2023 (Aicc2023) Chronological Framework And Associated Timescale For The European Project For Ice Coring In Antarctica (Epica) Dome C Ice Core. Climate Of The Past, 191(111), 2257–2286.
Abstract: The Epica (European Project For Ice Coring In Antarctica) Dome C (Edc) Ice Core Drilling In East Antarctica Reaches A Depth Of 3260 M. The Reference Edc Chronology, The Aicc2012 (Antarctic Ice Core Chronology 2012), Provides An Age Vs. Depth Relationship Covering The Last 800 Kyr (Thousands Of Years), With An Absolute Uncertainty Rising Up To 8000 Years At The Bottom Of The Ice Core. The Origins Of This Relatively Large Uncertainty Are Twofold: (1) The Delta 18 O Atm , Delta O 2 / N 2 And Total Air Content (Tac) Records Are Poorly Resolved And Show Large Gaps Over The Last 800 Kyr, And (2) Large Uncertainties Are Associated With Their Orbital Targets. Here, We Present New Highly Resolved Delta 18 O Atm , Delta O 2 / N 2 And Delta 15 N Measurements For The Edc Ice Core Covering The Last Five Glacial-Interglacial Transitions; A New Low-Resolution Tac Record Over The Period 440-800 Ka Bp (Ka: 1000 Years Before 1950); And Novel Absolute 81 Kr Ages. We Have Compiled Chronological And Glaciological Information Including Novel Orbital Age Markers From New Data On The Edc Ice Core As Well As Accurate Firn Modeling Estimates In A Bayesian Dating Tool To Construct The New Aicc2023 Chronology. For The First Time, Three Orbital Tools Are Used Simultaneously. Hence, It Is Possible To Observe That They Are Consistent With Each Other And With The Other Age Markers Over Most Of The Last 800 Kyr (70 %). This, In Turn, Gives Us Confidence In The New Aicc2023 Chronology. The Average Uncertainty In The Ice Chronology Is Reduced From 1700 To 900 Years In Aicc2023 Over The Last 800 Kyr ( 1 Sigma ). The New Timescale Diverges From Aicc2012 And Suggests Age Shifts Reaching 3800 Years Towards Older Ages Over Marine Isotope Stages (Miss) 5, 11 And 19. But The Coherency Between The New Aicc2023 Timescale And Independent Chronologies Of Other Archives (Italian Lacustrine Succession From Sulmona Basin, Dome Fuji Ice Core And Northern Alpine Speleothems) Is Improved By 1000 To 2000 Years Over These Time Intervals.
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Bouttes, N., Lhardy, F., Quiquet, A., Paillard, D., Goosse, H., & Roche, D. (2023). Deglacial Climate Changes As Forced By Different Ice Sheet Reconstructions. Climate Of The Past, , 102711–104211.
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Brun, F., King, O., Reveillet, M., Amory, C., Planchot, A., Berthier, E., et al. (2023). Everest South Col Glacier Did Not Thin During The Period 1984-2017. Cryosphere, 171(8), 3251–3268.
Abstract: The South Col Glacier Is A Small Body Of Ice And Snow (Approx. 0.2 Km(2)) Located At The Very High Elevation Of 8000Ma.S.L. (Above Sea Level) On The Southern Ridge Of Mt. Everest. A Recent Study By Potocki Et Al. (2022) Proposed That South Col Glacier Is Rapidly Losing Mass. This Is In Contradiction To Our Comparison Of Two Digital Elevation Models Derived From Aerial Photographs Taken In December 1984 And A Stereo Pleiades Satellite Acquisition From March 2017, From Which We Estimate A Mean Elevation Change Of 0.01 +/- 0.05M A(-1). To Reconcile These Results, We Investigate Some Aspects Of The Surface Energy And Mass Balance Of South Col Glacier. From Satellite Images And A Simple Model Of Snow Compaction And Erosion, We Show That Wind Erosion Has A Major Impact On The Surface Mass Balance Due To The Strong Seasonality In Precipitation And Wind And That It Cannot Be Neglected. Additionally, We Show That The Melt Amount Predicted By A Surface Energy And Mass Balance Model Is Very Sensitive To The Model Structure And Implementation. Contrary To Previous Findings, Melt Is Likely Not A Dominant Ablation Process On This Glacier, Which Remains Mostly Snow-Covered During The Monsoon.
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Burgard, C., Jourdain, N., Mathiot, P., Smith, R., Schaefer, R., Caillet, J., et al. (2023). Emulating Present And Future Simulations Of Melt Rates At The Base Of Antarctic Ice Shelves With Neural Networks. Journal Of Advances In Modeling Earth Systems, 151(121).
Abstract: Melt Rates At The Base Of Antarctic Ice Shelves Are Needed To Drive Projections Of The Antarctic Ice Sheet Mass Loss. Current Basal Melt Parameterizations Struggle To Link Open Ocean Properties To Ice-Shelf Basal Melt Rates For The Range Of Current Sub-Shelf Cavity Geometries Around Antarctica. We Present A Proof Of Concept Exploring The Potential Of Simple Deep Learning Techniques To Parameterize Basal Melt. We Train A Simple Feedforward Neural Network, Or Multilayer Perceptron, Acting On Each Grid Cell Separately, To Emulate The Behavior Of Circum-Antarctic Cavity-Resolving Ocean Simulations. We Find That This Kind Of Emulator Produces Reasonable Basal Melt Rates For Our Training Ensemble, At Least As Close As Or Closer To The Reference Than Traditional Parameterizations. On An Independent Ensemble Of Simulations That Was Produced With The Same Ocean Model But With Different Model Parameters, Cavity Geometries And Forcing, The Neural Network Yields Similar Results To Traditional Parameterizations On Present Conditions. In Much Warmer Conditions, Both Traditional Parameterizations And Neural Network Struggle, But The Neural Network Tends To Produce Basal Melt Rates Closer To The Reference Than A Majority Of Traditional Parameterizations. While This Shows That Such A Neural Network Is At Least As Suitable For Century-Scale Antarctic Ice-Sheet Projections As Traditional Parameterizations, It Also Highlights That Tuning Any Parameterization On Present-Like Conditions Can Introduce Biases And Should Be Used With Care. Nevertheless, This Proof Of Concept Is Promising And Provides A Basis For Further Development Of A Deep Learning Basal Melt Parameterization. A Warmer Ocean Around Antarctica Leads To Higher Melting Of The Floating Ice Shelves, Which Influence The Ice Loss From The Antarctic Ice Sheet And Therefore Sea-Level Rise. In Computer Simulations Of The Ocean, These Ice Shelves Are Often Not Represented. For Simulations Of The Ice Sheet, So-Called Parameterizations Are Used To Link The Oceanic Properties In Front Of The Shelf And The Melt At Their Base. We Show That This Link Can Be Emulated With A Simple Neural Network, Which Performs At Least As Well As Traditional Physical Parameterizations Both For Present And Much Warmer Conditions. This Study Also Proposes Several Potential Ways Of Further Improving The Use Of Deep Learning To Parameterize Basal Melt. We Show That Simple Neural Networks Produce Reasonable Basal Melt Rates By Emulating Circum-Antarctic Cavity-Resolving Ocean Simulationspredicted Melt Rates For Present And Warmer Conditions Are Similar Or Closer To The Reference Simulation Than Traditional Parameterizationswe Show That Neural Networks Are Suited To Be Used As Basal Melt Parameterizations For Century-Scale Ice-Sheet Projections
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Burgard, C., Jourdain, N., Mathiot, P., Smith, R., Schäfer, R., Caillet, J., et al. (2023). Emulating Present And Future Simulations Of Melt Rates At The Base Of Antarctic Ice Shelves With Neural Networks. Journal Of Advances In Modeling Earth Systems, 151(121).
Abstract: Melt Rates At The Base Of Antarctic Ice Shelves Are Needed To Drive Projections Of The Antarctic Ice Sheet Mass Loss. Current Basal Melt Parameterizations Struggle To Link Open Ocean Properties To Ice-Shelf Basal Melt Rates For The Range Of Current Sub-Shelf Cavity Geometries Around Antarctica. We Present A Proof Of Concept Exploring The Potential Of Simple Deep Learning Techniques To Parameterize Basal Melt. We Train A Simple Feedforward Neural Network, Or Multilayer Perceptron, Acting On Each Grid Cell Separately, To Emulate The Behavior Of Circum-Antarctic Cavity-Resolving Ocean Simulations. We Find That This Kind Of Emulator Produces Reasonable Basal Melt Rates For Our Training Ensemble, At Least As Close As Or Closer To The Reference Than Traditional Parameterizations. On An Independent Ensemble Of Simulations That Was Produced With The Same Ocean Model But With Different Model Parameters, Cavity Geometries And Forcing, The Neural Network Yields Similar Results To Traditional Parameterizations On Present Conditions. In Much Warmer Conditions, Both Traditional Parameterizations And Neural Network Struggle, But The Neural Network Tends To Produce Basal Melt Rates Closer To The Reference Than A Majority Of Traditional Parameterizations. While This Shows That Such A Neural Network Is At Least As Suitable For Century-Scale Antarctic Ice-Sheet Projections As Traditional Parameterizations, It Also Highlights That Tuning Any Parameterization On Present-Like Conditions Can Introduce Biases And Should Be Used With Care. Nevertheless, This Proof Of Concept Is Promising And Provides A Basis For Further Development Of A Deep Learning Basal Melt Parameterization. A Warmer Ocean Around Antarctica Leads To Higher Melting Of The Floating Ice Shelves, Which Influence The Ice Loss From The Antarctic Ice Sheet And Therefore Sea-Level Rise. In Computer Simulations Of The Ocean, These Ice Shelves Are Often Not Represented. For Simulations Of The Ice Sheet, So-Called Parameterizations Are Used To Link The Oceanic Properties In Front Of The Shelf And The Melt At Their Base. We Show That This Link Can Be Emulated With A Simple Neural Network, Which Performs At Least As Well As Traditional Physical Parameterizations Both For Present And Much Warmer Conditions. This Study Also Proposes Several Potential Ways Of Further Improving The Use Of Deep Learning To Parameterize Basal Melt. We Show That Simple Neural Networks Produce Reasonable Basal Melt Rates By Emulating Circum-Antarctic Cavity-Resolving Ocean Simulationspredicted Melt Rates For Present And Warmer Conditions Are Similar Or Closer To The Reference Simulation Than Traditional Parameterizationswe Show That Neural Networks Are Suited To Be Used As Basal Melt Parameterizations For Century-Scale Ice-Sheet Projections
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Burgos-Cuevas, A., Ruiz-Angulo, A., Ramos-Musalem, K., Palacios-Morales, C., & Garcia-Molina, C. (2023). Experimental Downslope Gravity Currents Over A Synthetic Topography. Atmosfera, 373, 383–399.
Abstract: Experimental Lock-Release Gravity Currents Are Investigated As They Propagate Downslope Over Varying Synthetic Topography. We Emulate And Investigate The Dynamics Of Thermally Driven Winds That Propagate Downslope While Interacting With The Roughness Of A Complex Topographic Surface. The Mixing Processes Between The Gravity Currents And Their Surroundings Are Studied With Particle Image Velocimetry (Piv), And Entrainment Is Quantified. The Magnitude Of The Entrainment Coefficient Is Shown To Increase As The Roughness Of The Slope Increases. Shadowgraph Visualizations Qualitatively Reproduce This Behavior. Finally, Pressure Fields Are Estimated From Velocity Fields, And Pressure Time Series Are Obtained Over Synthetic Stations Along The Topographic Surface. The Arrival Of Gravity Currents Is Shown To Be Detected In The Pressure Time Series. This Last Result May Help Detect Atmospheric Gravity Currents Using Only Surface Pressure Measurements.
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Caillet, J., Jourdain, N., Mathiot, P., Hellmer, H., & Mouginot, J. (2023). Drivers And Reversibility Of Abrupt Ocean State Transitions In The Amundsen Sea, Antarctica. Journal Of Geophysical Research-Oceans, 1281(1).
Abstract: Ocean Warming Around Antarctica Has The Potential To Trigger Marine Ice-Sheet Instabilities. It Has Been Suggested That Abrupt And Irreversible Cold-To-Warm Ocean Tipping Points May Exist, With Possible Domino Effect From Ocean To Ice-Sheet Tipping Points. A 1/4 & Deg; Ocean Model Configuration Of The Amundsen Sea Sector Is Used To Investigate The Existence Of Ocean Tipping Points, Their Drivers, And Their Potential Impact On Ice-Shelf Basal Melting. We Apply Idealized Atmospheric Perturbations Of Either Heat, Freshwater, Or Momentum Fluxes, And We Characterize The Key Physical Processes At Play In Warm-To-Cold And Cold-To-Warm Climate Transitions. Relatively Weak Perturbations Of Any Of These Fluxes Are Able To Switch The Amundsen Sea To An Intermittent Or Permanent Cold State, That Is, With Ocean Temperatures Close To The Surface Freezing Point And Very Low Ice-Shelf Melt Rate. The Transitions Are Reversible, That Is, Canceling The Atmospheric Perturbation Brings The Ocean System Back To Its Unperturbed State Within A Few Decades. All The Transitions Are Primarily Driven By Changes In Surface Buoyancy Fluxes Resulting From The Freshwater Flux Perturbation Or From Modified Net Sea-Ice Production Due To Either Heat Flux Or Sea-Ice Advection Anomalies. These Changes Affect The Vertical Ocean Stratification Over The Continental Shelf And Thereby The Eastward Undercurrent At The Shelf Break, Which Both Impact Ice-Shelf Melting. As Sea-Ice Induced Deep Convection Is Already Quite Limited In Present-Day Conditions, Surface Buoyancy Gain In A Warmer Climate Has Relatively Little Effect On Deep Ocean Properties Compared To Colder Climate Conditions.
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Camberlin, P., Togbedji, C., Pergaud, J., Berger, A., Aellig, R., Fink, A., et al. (2023). The Representation Of Dry-Season Low-Level Clouds Over Western Equatorial Africa In Reanalyses And Historical Cmip6 Simulations. Climate Dynamics, .
Abstract: Within The Equatorial Zone, Western Equatorial Africa (Wea) Has A Record Low Sunshine Duration During The June-September Dry Season Due To The Persistence Of Low Clouds. This Study Examines The Ability Of Two Reanalysis Products (Era5 And Merra-2) And Eight Cmip6 Models (Both Coupled And Atmosphere-Only Historical Simulations) To Reproduce The Climatology Of These Low Clouds, By Comparing It With Ground Observations And A Satellite Product. All Datasets Show A Reasonable Representation Of The Regional Distribution Of Low Clouds Over The Tropical Atlantic And The Neighbouring African Continent. However, Cmip6 Models Tend To Underestimate The Low Cloud Fraction, Especially Over Wea In The Coupled Simulations. This Underestimation Is Partly Due To An Insufficient Seasonal Sea-Surface Temperature (Sst) Cooling Over The Eastern Equatorial Atlantic From April To July In Most Models, Which Reduces The Lower-Tropospheric Stability (Lts). However, The Inability To Reproduce The Jjas Low Cloud Fraction Does Not Necessarily Scale With The Sst Biases Of The Cmip6 Models. Observed Interannual Variations Of Wea Low-Cloud Fraction Are Strongly Controlled By Lts, Itself Mostly Related To Atlantic Sst. The Strong Dependence Of Low Clouds On Interannual Sst Variations Is Captured By Most, But Not All The Cmip6 Models. Additional Drivers Of Interannual Variations Identified In This Study, Such As Mid-Tropospheric Temperatures Over Wea And Bight Of Bonny Surface Winds, Emerge Inconsistently In Cmip6. Further Analyses Are Needed To Disentangle The Roles Played By Sst And Independent Atmospheric Forcings On Wea Low Cloud Formation.
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Caracciolo, R., Escher, B., Lai, F., Nguyen, T., Le, T., Schlichting, R., et al. (2023). Impact Of A Megacity On The Water Quality Of A Tropical Estuary Assessed By A Combination Of Chemical Analysis And In-Vitro Bioassays. Science Of The Total Environment, 8778.
Abstract: Tropical Estuaries Are Threatened By Rapid Urbanization, Which Leads To The Spread Of Thousands Of Micropollutants And Poses An Environmental Risk To Such Sensitive Aqueous Ecosystems. In The Present Study, A Combination Of Chemical And Bioanalytical Water Characterization Was Applied To Investigate The Impact Of Ho Chi Minh Megacity (Hcmc, 9.2 Mil-Lion Inhabitants In 2021) On The Saigon River And Its Estuary And Provide A Comprehensive Water Quality Assessment. Water Samples Were Collected Along A 140-Km Stretch Integrating The River-Estuary Continuum From Upstream Hcmc Down To The Estuary Mouth In The East Sea. Additional Water Samples Were Collected At The Mouth Of The Four Main Ca-Nals Of The City Center. Chemical Analysis Was Performed Targeting Up To 217 Micropollutants (Pharmaceuticals, Plasti-Cizers, Pfass, Flame Retardants, Hormones, Pesticides). Bioanalysis Was Performed Using Six In-Vitro Bioassays For Hormone Receptor-Mediated Effects, Xenobiotic Metabolism Pathways And Oxidative Stress Response, Respectively, All Accompanied By Cytotoxicity Measurement. A Total Of 120 Micropollutants Were Detected And Displayed High Variabil-Ity Along The River Continuum With Total Concentration Ranging From 0.25 To 78 Mu G L-1. Among Them, 59 Micropollutants Were Ubiquitous (Detection Frequency >= 80 %). An Attenuation Was Observed In Concentration And Ef-Fect Proflles Towards The Estuary. The Urban Canals Were Identifled As Major Sources Of Micropollutants And Bioactivity To The River, And One Canal (Blatin Small Letter E With Circumflex And Acuten Nghe) Exceeded The Effect-Based Trigger Values Derived For Estrogenicity And Xenobiotic Metabolism. Iceberg Modelling Apportioned The Contribution Of The Quantifled And The Unknown Chemicals To The Mea-Sured Effects. Diuron, Metolachlor, Chlorpyrifos, Daidzein, Genistein, Climbazole, Mebendazole And Telmisartan Were Identified As Main Risk Drivers Of The Oxidative Stress Response And Xenobiotic Metabolism Pathway Activation. Our Study Reinforced The Need For Improved Wastewater Management And Deeper Evaluations Of The Occurrence And Fate Of Micropollutants In Urbanized Tropical Estuarine Environments.
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Cassel, M., Navratil, O., Liebault, F., Recking, A., Vazquez-Tarrio, D., Bakker, M., et al. (2023). Assessment Of Pebble Virtual Velocities By Combining Active Rfid Fixed Stations With Geophones. Earth Surface Processes And Landforms, .
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Cebrián-Piqueras, M., Palomo, I., Lo, V., López-Rodríguez, M., Filyushkina, A., Fischborn, M., et al. (2023). Leverage Points And Levers Of Inclusive Conservation In Protected Areas. Ecology And Society, 282(4).
Abstract: Inclusive Conservation Approaches That Effectively Conserve Biodiversity While Improving Human Well-Being Are Gaining Traction In The Face Of The Sixth Mass Extinction Of Biodiversity. Despite Much Theorization On The Governance Of Inclusive Conservation, Empirical Research On Its Practical Implementation Is Urgently Needed. Here, Using A Correlation Network Analysis And Drawing On Empirical Results From 263 Sites Described On The Web Platform Of The Panorama Initiative (Iucn), We Inductively Identified Global Clusters Of Conservation Outcomes In Protected And Conserved Areas. These Clusters Represent Five Conservation Foci Or Archetypes, Namely (I) Community-Based Conservation, (Ii) Sustainable Management, (Iii) Conflict Resolution, (Iv) Multi-Level And Co-Governance, And (V) Environmental Protection And Nature'S Contribution To People. Our Empirical Approach Further Revealed That Some Dimensions Of Inclusive Conservation Are Crucial As Leverage Points To Manage Protected Areas Related To These Clusters Successfully, Namely Improvements In The Socio-Cultural Context And Social Cohesion, Enhancing The Status And Participation Of Youth, Women, And Minorities, Improved Human Health, Empowerment Of Local Communities, Or Reestablishment Of Dialogue And Trust. We Highlight Inclusive Interventions Such As Education And Capacity Building, Development Of Alliances And Partnerships, And Enabling Sustainable Livelihoods, Or Governance Arrangements Led By Indigenous Peoples And Local Communities Or Private Actors, As Levers To Promote Positive Transformations In The Social-Ecological Systems Of Protected Areas. We Argue That Although Some Of The Leverage Points We Identified Are Less Targeted In Current Protected Area Management, They Can Represent Powerful Areas Of Intervention To Enhance Social And Ecological Outcomes In Protected Areas.
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Celli, G., Cairns, W., Scarchilli, C., Cuevas, C., Saiz-Lopez, A., Savarino, J., et al. (2023). Bromine, Iodine And Sodium Along The Eaiist Traverse: Bulk And Surface Snow Latitudinal Variability. Environmental Research, 2392.
Abstract: During The East Antarctic International Ice Sheet Traverse (Eaiist, December 2019), In An Unexplored Part Of The East Antarctic Plateau, Snow Samples Were Collected To Expand Our Knowledge Of The Latitudinal Variability Of Iodine, Bromine And Sodium As Well As Their Relation In Connection With Emission Processes And Photochemical Activation In This Unexplored Area. A Total Of 32 Surface (0-5 Cm) And 32 Bulk (Average Of 1 M Depth) Samples Were Taken And Analysed By Inductively Coupled Plasma Mass Spectrometry (Icp-Ms). Our Results Show That There Is No Relevant Latitudinal Trend For Bromine And Sodium. For Bromine They Also Show That It Has No Sig-Nificant Post-Depositional Mechanisms While Its Inland Surface Snow Concentration Is Influenced By Spring Coastal Bromine Explosions. Iodine Concentrations Are Several Orders Of Magnitude Lower Than Bromine And Sodium And They Show A Decreasing Trend In The Surface Samples Concentration Moving Southward. This Suggests That Other Processes Affect Its Accumulation In Surface Snow, Probably Related To The Radial Reduction In The Ozone Layer Moving Towards Central Antarctica. Even Though All Iodine, Bromine And Sodium Present Similar Long-Range Transport From The Dominant Coastal Antarctic Sources, The Annual Seasonal Cycle Of The Ozone Hole Over Antarctica Increases The Amount Of Uv Radiation (In The 280-320 Nm Range) Reaching The Surface, Thereby Affecting The Surface Snow Photoactivation Of Iodine. A Comparison Between The Bulk And Surface Samples Supports The Conclusion That Iodine Undergoes Spring And Summer Snow Recycling That Increases Its Atmospheric Lifetime, While It Tends To Accumulate During The Winter Months When Photochemistry Ceases.
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Chabi, B., Alassane, A., Kpegli, K., Lawson, F., Zakari, A., Koukpohounsi, B., et al. (2023). Characterising Groundwater And Surface-Water Interconnections Using Hydrogeology, Hydrochemistry And Stable Isotopes In The Oueme Delta, Southern Benin. Hydrogeology Journal, .
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Chahinian, N., Alcoba, M., Dembele, N., Cazenave, F., & Bouvier, C. (2023). Evaluation Of An Early Flood Warning System In Bamako (Mali): Lessons Learned From The Flood Of May 2019. Journal Of Flood Risk Management, .
Abstract: Devastating Floods Have Plagued Many West African Cities In The Past Decades. In An Attempt To Reduce Flood Damage In Bamako (Mali), An Early Warning System (Ews) Demonstrator (Raincell App) Was Developed For Flash Floods. On 16 May 2019, While The Demonstrator Was Partially Operational, An Intense Rainfall Event Led To Devastating Floods. We Carried Out An Experience Feedback On This Flood Event By Comparing Ews Simulations To The Results Of A Field Survey. Given The Synoptic Situation And The Rapid Development Pattern Of The Storm, None Of The Global Forecasting Systems Were Able To Foresee Its Occurrence And Magnitude. The Hydrological Model Developed As Part Of The Demonstrator Correctly Identified Most Of The Locations Where Overbank Flow Occurred. In The Absence Of Data, The Predicted Discharge And Volume Values Could Not Be Validated. However, They Are Realistic Based On The Water Levels Reported In The Post-Disaster Needs Assessment Report. It Would Be Advisable To Couple It To A Two-Dimensional Hydraulic Model And Add Discharge And Water Level Monitoring To The Already Existing Rainfall Surveillance Scheme To Further Improve The System'S Performance. Increasing The Local Population'S Awareness Of The Dangers Of Clogged Waterways Is Also Mandatory.
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Chaillot, J., Dasari, S., Fleurbaey, H., Daeron, M., Savarino, J., & Kassi, S. (2023). High-Precision Laser Spectroscopy Of H<Sub>2</Sub>S For Simultaneous Probing Of Multiple-Sulfur Isotopes. Environmental Science-Advances, 2(1), 78–86.
Abstract: The Simultaneous Monitoring Of The Triple Stable S-Isotopes (S-32, S-33 And S-34) Of Hydrogen Sulfide Has Been Conducted With A Vcof-Crds Set-Up (A V-Shaped Cavity For Optical Feedback Coupled To A Cavity Ring Down Spectrometer). The Spectroscopic Investigation Of H2S Was Performed For The First Time In The Near-Infrared Region (Approximate To 1.6 Mu M) With A Stabilized Laser Of Linewidth < 1 Khz And An Optical Pathlength Of 90 Km, Providing Unparalleled Sensitivity And Precision. Pressure Dependencies Of The System Were Explored To As Low As 0.1 Mbar Revealing The Lamb Dip Feature Of The Isotopologue Transitions. A Model Was Developed To Fit Experimental Spectra With Accuracy Better By One Order Of Magnitude Than What The Literature Provides. The S-Isotope Composition Delta S-34 And S-Isotope Anomaly Delta S-33 Are Determined With An Uncertainty Of 5 X 10(-6) Within 10 Seconds, Limited By H2S Reactivity Inside The Measurement Cell. Such High Precision Represents A New Benchmark For Laser Spectroscopy Of H2S And Optical Determination Of Isotopic Measurements And Makes Vcof-Crds A Promising Tool For A Plethora Of Future Applications.
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Champagne, O., Aellig, R., Fink, A., Philippon, N., Camberlin, P., Moron, V., et al. (2023). Climatology Of Low-Level Clouds Over Western Equatorial Africa Based On Ground Observations And Satellites. Journal Of Climate, , 428944–430644.
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Champagne, O., Arain, A., Wang, S., & Leduc, M. (2023). Future Change In Amplitude And Timing Of High-Flow Events In A Canadian Subarctic Watershed. Cold Regions Science And Technology, 2092.
Abstract: The Hudson Bay Basin Is A Large Contributor Of Freshwater Input In The Arctic Ocean And Is Also An Area Affected By Destructive Spring Floods. In This Study, The Hydrological Model Mesh (Modelisation Environmentale Com-Munautaire -Surface And Hydrology) Was Set Up For The Groundhog River Watershed Situated In The Hudson Bay Basin, To Simulate The Future Evolution Of Streamflow And Annual Maximum Streamflow. Mesh Was Forced By Meteorological Data From Era5 Reanalyses In The Historical Period (1979-2018) And 12 Models Of The Coupled Model Intercomparison Project Phase 5 (Cmip5) Downscaled With The Canadian Regional Climate Model Version 5 (Crcm5) In Historical (1979-2005) And Scenario Period (2006-2098). The Projections Consistently Indicate An Earlier Spring Flow And A Reduction In The Amount Of Annual Maximum Streamflow By The End Of The 21St Century. Under The Rcp8.5 Scenario, The Annual Maximum Streamflow Occurring In The Spring Is Expected To Be Advanced By 2 Weeks And Reduced On Average From 852 M3/S (+/- 265) In The Historical Period (1979-2018) To 717M3/S (+/- 250) By The End Of The 21St Century (2059-2098). Because The Seasonal Projection Of Streamflow Was Not Investigated In Previous Studies, This Work Is An Important First Step To Assess The Seasonal Change Of Streamflow In The Hudson Bay Region Under Climate Change.
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Chung, A., Parrenin, F., Steinhage, D., Mulvaney, R., Martín, C., Cavitte, M., et al. (2023). Stagnant Ice And Age Modelling In The Dome C Region, Antarctica. Cryosphere, 171(8), 3461–3483.
Abstract: The European Beyond Epica Project Aims To Extract A Continuous Ice Core Of Up To 1.5 Ma, With A Maximum Age Density Of 20 Kyr M(-1) At Little Dome C (Ldc). We Present A 1D Numerical Model Which Calculates The Age Of The Ice Around Dome C. The Model Inverts For Basal Conditions And Accounts Either For Melting Or For A Layer Of Stagnant Ice Above The Bedrock. It Is Constrained By Internal Reflecting Horizons Traced In Radargrams And Dated Using The Epica Dome C (Edc) Ice Core Age Profile. We Used Three Different Radar Datasets Ranging From A 10 000 Km(2) Airborne Survey Down To 5 Km Long Ground-Based Radar Transects Over Ldc. We Find That Stagnant Ice Exists In Many Places, Including Above The Ldc Relief Where The New Beyond Epica Drill Site (Beldc) Is Located. The Modelled Thickness Of This Layer Of Stagnant Ice Roughly Corresponds To The Thickness Of The Basal Unit Observed In One Of The Radar Surveys And In The Autonomous Phase-Sensitive Radio-Echo Sounder (Apres) Dataset. At Beldc, The Modelled Stagnant Ice Thickness Is 198 +/- 44 M And The Modelled Oldest Age Of Ice Is 1.45 +/- 0.16 Ma At A Depth Of 2494 +/- 30 M. This Is Very Similar To All Sites Situated On The Ldc Relief, Including That Of The Million Year Ice Core Project Being Conducted By The Australian Antarctic Division. The Model Was Also Applied To Radar Data In The Area 10-15 Km North Of Edc (North Patch), Where We Find Either A Thin Layer Of Stagnant Ice (Generally <60 M) Or A Negligible Melt Rate (<0.1 Mm Yr(-1)). The Modelled Maximum Age At North Patch Is Over 2 Ma In Most Places, With Ice At 1.5 Ma Having A Resolution Of 9-12 Kyr M(-1), Making It An Exciting Prospect For A Future Oldest Ice Drill Site.
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Clauzel, L., Menegoz, M., Gilbert, A., Gagliardini, O., Six, D., Gastineau, G., et al. (2023). Sensitivity Of Glaciers In The European Alps To Anthropogenic Atmospheric Forcings: Case Study Of The Argentiere Glacier. Geophysical Research Letters, .
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Cook, S., Gillet-Chaulet, F., & Fuerst, J. (2023). Robust Reconstruction Of Glacier Beds Using Transient 2D Assimilation With Stokes. Journal Of Glaciology, .
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Cook, S., Jouvet, G., Millan, R., Rabatel, A., Zekollari, H., & Dussaillant, I. (2023). Committed Ice Loss In The European Alps Until 2050 Using A Deep-Learning-Aided 3D Ice-Flow Model With Data Assimilation. Geophysical Research Letters, 505(232).
Abstract: Modeling The Short-Term (<50 Years) Evolution Of Glaciers Is Difficult Because Of Issues Related To Model Initialization And Data Assimilation. However, This Timescale Is Critical, Particularly For Water Resources, Natural Hazards, And Ecology. Using A Unique Record Of Satellite Remote-Sensing Data, Combined With A Novel Optimisation And Surface-Forcing-Calculation Method Within The Framework Of The Deep-Learning Based Instructed Glacier Model, We Are Able To Ameliorate Initialization Issues. We Thus Model The Committed Evolution Of All Glaciers In The European Alps Up To 2050 Using Present-Day Climate Conditions, Assuming No Future Climate Change. We Find That The Resulting Committed Ice Loss Exceeds A Third Of The Present-Day Ice Volume By 2050, With Multi-Kilometer Frontal Retreats For Even The Largest Glaciers. Our Results Show The Importance Of Modeling Ice Dynamics To Accurately Retrieve The Ice-Thickness Distribution And To Predict Future Mass Changes. Thanks To High-Performance Gpu Processing, We Also Demonstrate Our Method'S Global Potential.
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Cuesta-Valero, F., Beltrami, H., Garcia-Garcia, A., Krinner, G., Langer, M., Macdougall, A., et al. (2023). Continental Heat Storage: Contributions From The Ground, Inland Waters, And Permafrost Thawing. Earth System Dynamics, , 60966–62766.
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Cusicanqui, D., Bodin, X., Duvillard, P., Schoeneich, P., Revil, A., Assier, A., et al. (2023). Glacier, Permafrost And Thermokarst Interactions In Alpine Terrain: Insights From Seven Decades Of Reconstructed Dynamics Of The Chauvet Glacial And Periglacial System (Southern French Alps). Earth Surface Processes And Landforms, .
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Da Silva, E., Woolliams, E., Picot, N., Poisson, J., Skourup, H., Moholdt, G., et al. (2023). Towards Operational Fiducial Reference Measurement (Frm) Data For The Calibration And Validation Of The Sentinel-3 Surface Topography Mission Over Inland Waters, Sea Ice, And Land Ice. Remote Sensing, 151(191).
Abstract: The Copernicus Sentinel-3 Surface Topography Mission (Stm) Land Altimetry Provides Valuable Surface Elevation Information Over Inland Waters, Sea Ice, And Land Ice, Thanks To Its Synthetic Aperture Radar (Sar) Altimeter And Its Orbit That Covers High-Latitude Polar Regions. To Ensure That These Measurements Are Reliable And To Maximise The Return On Investment, Adequate Validation Of The Geophysical Retrieval Methods, Processing Algorithms, And Corrections Must Be Performed Using Independent Observations. The Eu-Esa Project St3Tart (Started July 2021) Aims To Generalise The Concept Of Fiducial Reference Measurements (Frms) For The Copernicus Sentinel-3 Stm. This Work Has Gathered Existing Data, Made New Observations During Field Campaigns, And Ensured That These Observations Meet The Criteria Of Frm Standards So That They Can Be Used To Validate Sentinel-3 Stm Land Altimetry Products Operationally. A Roadmap For The Operational Provision Of The Frm, Including The Definition, Consolidation, And Identification Of The Most Relevant And Cost-Effective Methods And Protocols To Be Maintained, Supported, Or Implemented, Has Been Developed. The Roadmap Includes Guidelines For Si Traceability, Definitions Of Frm Measurement Procedures, Processing Methods, And Uncertainty Budget Estimations.
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Dang, D., Ha, Q., Némery, J., & Strady, E. (2023). The Seasonal Variations In The Interactions Between Rare Earth Elements And Organic Matter In Tropical Rivers. Chemical Geology, 6386.
Abstract: The Escalation Of Global Demands For Critical Minerals To Facilitate The Green Energy Transition Creates Emerging Needs To Better Understand Their Environmental Behaviours. Several Nations Recognize Rare Earth Elements (Rees) As Priority Critical Minerals And Emphasize The Necessity To Evaluate Their Environmental Mobility And Potential Effects On Natural Ecosystems And Human Health. Here, We Investigated The Seasonal Variations In Dissolved Concentrations Of Rees And Their Leachable Fractions From Suspended Particles In Samples Collected Bi-Weekly From The Sai Gon And Dong Nai Rivers In Southern Vietnam. The Investigation Period Extended Over Sixteen Months, Including A Transition From Wet To Dry Seasons. We Reported Significant Mobility Of Rees In The River Waters During The Wet Season Due To Watershed Runoff, Especially In Sai Gon River With The Occurrence Of Acid Sulphate Soils. Dissolved Ree Concentrations In The Dry Season Were Significantly Lower Because Of The Interactions With Organic-Rich Particles (Up To 13% Of Particulate Organic Carbon, Poc) Mainly Derived From Phytoplankton Materials. The Conditional Distribution Coefficients (Logkd From 5 To 7 For Pr) Were Proportional To Poc Content. The Scavenging Capacity Of Particulate Organic Matter Also Led To Affect The Fractionation Between Light Rees And Heavy Rees In Solution, And The Characteristic Middle Ree-Enrichment Patterns For The Leachable Rees Fraction. We Also Reported Significant Eu Anomalies (Eu/Eu* Up To 7) In The Dong Nai River During The Dry Season And Associated This Observation With The Decomposition Of Organic Matter That Previously Accumulated Eu. However, Further Studies Are Required To Confirm This Hypothesis Because Of Small Reservoir Effects; Elevated Eu Anomalies Were Observed In Water Samples With Low Dissolved Eu Concentrations.
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Dasari, S., Paris, G., Pei, Q., Cong, Z., & Widory, D. (2023). Tracing The Origin Of Elevated Springtime Atmospheric Sulfate On The Southern Himalayan-Tibetan Plateau. Environmental Science-Advances, 2(8), 1110–1118.
Abstract: The Himalayan Tibetan Plateau (Htp) Is One Of The World'S Most Climate-Sensitive Regions Outside The Polar Regions. Here, The Climate-Air Quality-Hydrological Cycle Affecting Sulfate Aerosols Remains Sparsely Investigated, With Their Source Origin(S) Requiring Further Investigation. We Tracked The Evolution Of Sulfur Mass-Independent Isotope Fractionation [S-Mif I.E., Delta S-33 Not Equal 0]-As A Potential Source Tracer-In Springtime Aerosol Sulfate Over The Southern Htp. In A First, At The Southern Htp High-Altitude Receptor Site Qomolangma-Mt. Everest Station, Qoms, Similar To 4300 M A.S.L., Elevated Sulfate Concentrations And S-Mif Were Both Found To Be Associated With Biomass Burning Aerosols (So42- And Delta S-33 Vs. K+: R-2 = 0.92 [P < 0.001] And 0.61[P < 0.005], Respectively). This Is In Stark Contrast To Delta S-33 Aerosol Records From The Central Htp And A Downwind Mountainous Site Wherein Anomalous Sulfur Has Been Linked To Stratospheric Intrusions In The Past, And Geological Lake Records From The Region Which Link The Origin Of Modern Sulfate On The Htp To The Influx Of Mineral Dust, Respectively. The Findings Suggest That There Are Yet Unknown Biomass Combustion-Related Processes (E.G., Crop-Residue And Waste Burning, Wildfires) Plausibly Generating Positive Mif In Sulfur, Which Could Have Implications For Historical S-Isotope Records. Comparing The Triple-S-Isotope Imprint In Aerosol Sulfate On The Htp And Its Surrounding Regions Reveals The Existence Of Spatial Heterogeneity In The Dominance Of Competing Sulfate Transport And Formation Processes With Implications For The Regional Tropospheric Chemical And Radiation Budgets.
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Deen, T., Arain, M., Champagne, O., Chow-Fraser, P., & Martin-Hill, D. (2023). Impacts Of Climate Change On Streamflow In The Mckenzie Creek Watershed In The Great Lakes Region. Frontiers In Environmental Science, .
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Deléage, É. (2023). Well-Posedness Of Reynolds Averaged Equations For Compressible Fluids With A Vanishing Pressure. Mathematical Methods In The Applied Sciences, .
Abstract: We Show That The Reynolds Averaged Equations For Compressible Fluids (Neglecting Third Order Correlations) Are Well-Posed In Hs$$ {H} Circumflex S $$ When The Pressure Vanishes In Dimensions D=2$$ D Equal To 2 $$ And 3. In Order To Do This, We Show That The System Is Friedrichs-Symmetrizable. This Model Belongs To The Class Of Non-Conservative Hyperbolic Systems. Hence The Usual Symmetrisation Method For Conservation Laws Can Not Be Used Here.
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Deng, J., Camenen, B., Legout, C., & Nord, G. (2023). Estimation Of Fine Sediment Stocks In Gravel Bed Rivers Including The Sand Fraction. Sedimentology, .
Abstract: Fine Sediment Stored In The Gravel Bed Is An Important Component Of River Systems. Current Field Protocols Usually Allow Evaluation Of The Silt-Clay Fraction Of Fine Sediment Stocks Only And Neglect The Sand Fraction. This Study Proposes A New Protocol To Quantify Fine Sediment Stocks, Including The Sand Fraction Inside The Gravel Bed Matrix. Fine Sediment Stocks Were Sampled Within Patches Of 0.30 M X 0.30 M On The Dry Gravel Bed Surface, Separating The Surface Layer And The Subsurface Layer. The Grain-Size Distribution Of The Samples Was Obtained By Field Sieving (10 Mm, 2 Mm, 500 Mu M And 100 Mu M) Over A Bucket, Using A Known Volume Of Water. The Mass Of The Fraction Below 100 Mu M Was Measured Based On The Concentration Within The Bucket. The Local Stocks Were Then Integrated Over The Whole River Reach By Assigning Local Stocks To Facies, In Which Fine Sediment Stocks Were Assumed To Be Homogeneously Distributed. The Methodology Was Applied To A 1 Km Long Reach Of The River Galabre (Southern French Alps), Characterized By Significant Fine Sediment Stocks And Upstream Sediment Input. Results From Local Measurements Show A Large Amount Of Sand In Both Surface And Subsurface Layers. The Quantity Of Sand Can Reach Up To Three Times The Quantity Of Silt-Clay. An Estimation Of Porosity Showed That Fine Material May Play An Important Role In Structuring The Bed, Since Porosity Increases With Increasing Fine Sediment Content. The Potential Fine Sediment Stock That Can Be Resuspended Due To Channel Migration Is Found To Be Of The Same Order Of Magnitude As The Sediment Budget Estimated From The Measured Flux In The Upstream Hydrometric Station Of The Studied Reach.
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Denisenko, D., Richard, G., & Chambon, G. (2023). A Consistent Three-Equation Shallow-Flow Model For Bingham Fluids. Journal Of Non-Newtonian Fluid Mechanics, 3213.
Abstract: We Derive A Model For Bingham Fluid Flows Down An Inclined Plane With A Consistent Asymptotic Method In The Shallow-Flow Approximation. The Variables Are Expanded Up To The First Order Of Accuracy Both In The Sheared And Pseudo-Plug Layers. The Divergence Of The Strain Rate, Which Is Obtained In Classical Approaches, Is Here Avoided By A Specific Regularization Of The Rheology Allowing To Implement A Regular Perturbation Method In The Whole Fluid Domain. Unlike Classical Regularization Methods, The Material Is Here Characterized By A True Yield Stress. Below The Yield Point, The Behavior Is Perfectly Rigid. An Alternative Tensor Expression Of The Constitutive Law Is Proposed. In Particular, The Assumption Of An Alignment Between The Yield-Stress Tensor And The Strain-Rate Tensor Is Removed. The Model Is Derived By Averaging The Mass, Momentum And Energy Balance Equations Over The Depth. This Yields A Hyperbolic Model Of Three Equations For The Fluid Depth, The Average Velocity And A Third Variable, Called Enstrophy, Related To The Variance Of The Velocity. The Model Features New Relaxation Source Terms And Admits An Exact Balance Energy Equation. The Velocity Field In The Depth Is Consistently Reconstructed Using Only The Variables Of The Depth-Averaged Model Without Any Derivative. The Physical Relevance Of The Enstrophy Is Related To The Shape Of The Velocity Profile. The Linear Stability Of A Uniform Solution Is Investigated For This Model, Showing A Stabilizing Effect Of The Plasticity. Roll Waves Are Simulated Numerically Using A Classical Godunov'S Scheme. The Model For A Newtonian Fluid Is Presented As A Particular Case.
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Deremble, B., Uchida, T., Dewar, W., & Samelson, R. (2023). Eddy-Mean Flow Interaction With A Multiple Scale Quasi Geostrophic Model. Journal Of Advances In Modeling Earth Systems, 151(101).
Abstract: Parameterization Of Mesoscale Eddies In Coarse Resolution Ocean Models Is Necessary To Include The Effect Of Eddies On The Large-Scale Oceanic Circulation. We Propose To Use A Multiple-Scale Quasi-Geostrophic (Msqg) Model To Capture The Eddy Dynamics That Develop In Response To A Prescribed Large-Scale Flow. The Msqg Model Consists In Extending The Traditional Quasi Geostrophic (Qg) Dynamics To Include The Effects Of A Variable Coriolis Parameter And Variable Background Stratification. Solutions To This Msqg Equation Are Computed Numerically And Compared To A Full Primitive Equation Model. The Large-Scale Flow Field Permits Baroclinically Unstable Qg Waves To Grow. These Instabilities Saturate Due To Non-Linearities And A Filtering Method Is Applied To Remove Large-Scale Structures That Develop Due To The Upscale Cascade. The Resulting Eddy Field Represents A Dynamically Consistent Response To The Prescribed Background Flow, And Can Be Used To Rectify The Large-Scale Dynamics. Comparisons Between Gent-Mcwilliams Eddy Parameterization And The Present Solutions Show Large Regions Of Agreement, While Also Indicating Areas Where The Eddies Feed Back Onto The Large Scale In A Manner That The Gent-Mcwilliams Parameterization Cannot Capture. Also Of Interest Is The Time Variability Of The Eddy Feedback Which Can Be Used To Build Stochastic Eddy Parameterizations.
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Deremble, B., Uchida, T., Dewar, W., & Samelson, R. (2023). Eddy-Mean Flow Interaction With A Multiple Scale Quasi Geostrophic Model. Journal Of Advances In Modeling Earth Systems, 151(101).
Abstract: Parameterization Of Mesoscale Eddies In Coarse Resolution Ocean Models Is Necessary To Include The Effect Of Eddies On The Large-Scale Oceanic Circulation. We Propose To Use A Multiple-Scale Quasi-Geostrophic (Msqg) Model To Capture The Eddy Dynamics That Develop In Response To A Prescribed Large-Scale Flow. The Msqg Model Consists In Extending The Traditional Quasi Geostrophic (Qg) Dynamics To Include The Effects Of A Variable Coriolis Parameter And Variable Background Stratification. Solutions To This Msqg Equation Are Computed Numerically And Compared To A Full Primitive Equation Model. The Large-Scale Flow Field Permits Baroclinically Unstable Qg Waves To Grow. These Instabilities Saturate Due To Non-Linearities And A Filtering Method Is Applied To Remove Large-Scale Structures That Develop Due To The Upscale Cascade. The Resulting Eddy Field Represents A Dynamically Consistent Response To The Prescribed Background Flow, And Can Be Used To Rectify The Large-Scale Dynamics. Comparisons Between Gent-Mcwilliams Eddy Parameterization And The Present Solutions Show Large Regions Of Agreement, While Also Indicating Areas Where The Eddies Feed Back Onto The Large Scale In A Manner That The Gent-Mcwilliams Parameterization Cannot Capture. Also Of Interest Is The Time Variability Of The Eddy Feedback Which Can Be Used To Build Stochastic Eddy Parameterizations.
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Dethinne, T., Glaude, Q., Picard, G., Kittel, C., Alexander, P., Orban, A., et al. (2023). Sensitivity Of The Mar Regional Climate Model Snowpack To The Parameterization Of The Assimilation Of Satellite-Derived Wet-Snow Masks On The Antarctic Peninsula. Cryosphere, 171(101), 4267–4288.
Abstract: Both Regional Climate Models (Rcms) And Remote Sensing (Rs) Data Are Essential Tools In Understanding The Response Of Polar Regions To Climate Change. Rcms Can Simulate How Certain Climate Variables, Such As Surface Melt, Runoff And Snowfall, Are Likely To Change In Response To Different Climate Scenarios But Are Subject To Biases And Errors. Rs Data Can Assist In Reducing And Quantifying Model Uncertainties By Providing Indirect Observations Of The Modeled Variables On The Present Climate. In This Work, We Improve On An Existing Scheme To Assimilate Rs Wet Snow Occurrence Data With The “Modele Atmospherique Regional” (Mar) Rcm And Investigate The Sensitivity Of The Rcm To The Parameters Of The Scheme. The Assimilation Is Performed By Nudging The Mar Snowpack Temperature To Match The Presence Of Liquid Water Observed By Satellites. The Sensitivity Of The Assimilation Method Is Tested By Modifying Parameters Such As The Depth To Which The Mar Snowpack Is Warmed Or Cooled, The Quantity Of Water Required To Qualify A Mar Pixel As “Wet” (0.1 % Or 0.2 % Of The Snowpack Mass Being Water), And Assimilating Different Rs Datasets. Data Assimilation Is Carried Out On The Antarctic Peninsula For The 2019-2021 Period. The Results Show An Increase In Meltwater Production (+66.7 % On Average, Or +95 Gt), Along With A Small Decrease In Surface Mass Balance (Smb) (-4.5 % On Average, Or -20 Gt) For The 2019-2020 Melt Season After Assimilation. The Model Is Sensitive To The Tested Parameters, Albeit With Varying Orders Of Magnitude. The Prescribed Warming Depth Has A Larger Impact On The Resulting Surface Melt Production Than The Liquid Water Content (Lwc) Threshold Due To Strong Refreezing Occurring Within The Top Layers Of The Snowpack. The Values Tested For The Lwc Threshold Are Lower Than The Lwc For Typical Melt Days (Approximately 1.2 %) And Impact Results Mainly At The Beginning And End Of The Melting Period. The Assimilation Method Will Allow For The Estimation Of Uncertainty In Mar Meltwater Production And Will Enable The Identification Of Potential Issues In Modeling Near-Surface Snowpack Processes, Paving The Way For More Accurate Simulations Of Snow Processes In Model Projections.
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Diaz, E., Varando, G., Johnson, J., & Camps-Valls, G. (2023). Learning Latent Functions For Causal Discovery. Machine Learning-Science And Technology, .
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Didi, S., Diakhate, M., & Diedhiou, A. (2023). Changes In The West Africa Monsoon Precipitation Extremes During Enso Developing Phases. Atmosphere-Ocean, .
Abstract: A 37-Year Record Of Rainfall Gridded Data Covering West Africa And A Global Sea Surface Temperature (Sst) Dataset Are Used To Investigate The Remote Influence Of Sst Anomalies In The Equatorial Pacific On The Interannual Variability Of West Africa'S Extreme Rainfall Indices Over The Period 1981-2018. The Top Five (5) Years With The Strongest And Weakest Peak Of Nino3.4 Sst Monthly Anomalies Are Selected, And May-To-September (Mjjas) Composite Anomalies Of The Total And Extreme Rainfall Indices Are Performed. Results Reveal That Equatorial Pacific Sst'S Impacts On Daily Rainfall Intensity Are Generally More Robust Than That On Their Frequency. The Significant Changes In The Mean Zonal Atmospheric Circulation Associated With The Sst Lead To Significant Dynamic And Thermodynamic Changes That Affect The West African Monsoon System Locally. During El Nino (La Nina) Years, (I) A Weakening (Strengthening) Of The Tropical Easterly Jet (Tej), (Ii) A Strengthening (Weakening), And Southward (Northward) Shift Position Of The African Easterly Jet (Aej), And (Iii) A Decrease (Increase) Of The Monsoon Flow Are Noted. These Changes In The Atmospheric Circulation Prevent (Encourage) A Supply Of Moisture, Resulting In A Reduction (Increase) In Extreme Precipitation Observed Across West Africa. Equatorial Eastern Pacific Warming (Cooling) Is Also Shown To Lead To Stable (Unstable) Atmospheric Conditions Over West Africa That Block (Generate) The Development Of Convective Systems.
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Dillon, K., Tignat-Perrier, R., Joly, M., Grogan, S., Larose, C., Amato, P., et al. (2023). Comparison Of Airborne Bacterial Populations Determined By Passive And Active Air Sampling At Puy De Dome, France. Aerosol And Air Quality Research, .
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Do Amaral, F., Trung, T., Pellarin, T., & Gratiot, N. (2023). Datasets Of High-Resolution Water Level And Discharge From The Saigon-Dong Nai Estuary System Impacted By A Developing Megacity, Ho Chi Minh City-ViETNAm. Data In Brief, .
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Dominutti, P., Borlaza, L., Sauvain, J., Thuy, V., Houdier, S., Suarez, G., et al. (2023). Source Apportionment Of Oxidative Potential Depends On The Choice Of The Assay: Insights Into 5 Protocols Comparison And Implications For Mitigation Measures. Environmental Science-Atmospheres, 3(101), 1497–1512.
Abstract: The Oxidative Potential (Op) Of Particulate Matter (Pm) Has Recently Been Considered As A Viable Health-Based Metric Of Pm Exposure. Several Acellular Assays Have Been Developed To Assess Op, But There Is No Clear Consensus In The Methodology Or Protocols Used That Allows Inter-Comparison Between Studies. This Research Investigates Five Different Acellular Op Assays And Their Sensitivities With The Chemical Composition Of Atmospheric Particulate Matter (Pm10) And Its Emission Sources. We Revisited And Evaluated Pm10 Samples Collected Over One Year In The Urban Alpine City Of Grenoble, France. The Op Of Pm10 Was Assessed By Integrating Assays Commonly Found In The Literature, Such As Ascorbic Acid (Aa), Dithiothreitol (Dtt) And 2,7-Dichlorofluorescein (Dcfh) But Also Adding Novel And Less Explored Assays Such As Ferric-Xylenol Orange (Fox), And A Direct Ros-Quantification Through Oh. Detailed Source Apportionment Of Pm Using Positive Matrix Factorisation (Pmf) Previously Performed Was Coupled With Multiple Linear Regression (Mlr) Models To Determine The Op Contribution Of Pm10 Sources. The Results Highlight The Importance Of Seasonality In The Mass Contributions Of Each Source And Its Corresponding Influence On Op. These Seasonal Differences Helped To Identify The Specific Reactivity For Each Studied Op Assay. In Winter, A Good Agreement Was Found Between All The Op Assays With Anthropogenic Sources. However, During Warmer Months, With A Reduction In The Share Of Anthropogenic Emissions, A Higher Impact From Biogenic And Secondary Organic-Related Aerosols Has Been Found. Our Results Also Show A Dissimilar Sensitivity Of Each Op To The Pm10 Sources, Likely Associated With The Chemical Composition And Chemical Processes Involved. Thus, Our Findings Show The Importance Of Combining Various Op Assays To Capture Different Sensitivities To Redox-Active Species To Get A Clearer Picture Of The Intrinsic Capacity Of Pm Sources To Cause Damaging Oxidative Reactions In The Lung. Providing The Heterogeneity Of Sources Obtained With The Different Op Assays For A Given Ambient Pm Exposure, The Choice Of A Single Or A Combination Of Op Method(S) Must Be Rationally Evaluated As Part Of The Assessment Strategy. Such A Choice Would Offer Valuable Source-Related Information As A Powerful Tool To Better Understand The Nature And The Intensity Of Air Pollution And Envisage The Targeted Sources For Future Mitigation Policies.
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Dominutti, P., Hopkins, J., Shaw, M., Mills, G., Le, H., Huy, D., et al. (2023). Evaluating Major Anthropogenic Voc Emission Sources In Densely Populated ViETNAmese Cities. Environmental Pollution, .
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Dubo, T., Palomo, I., Camacho, L., Locatelli, B., Cugniet, A., Racinais, N., et al. (2023). Nature-Based Solutions For Climate Change Adaptation Are Not Located Where They Are Most Needed Across The Alps. Regional Environmental Change, 232(1).
Abstract: Climate Change Impacts Social-Ecological Systems In Mountainous Areas By Increasing Certain Natural Disasters And Changing Nature'S Contributions To People (Ncp). Nature-Based Solutions (Nbs) Are Increasingly Implemented To Help Local Communities Adapt To Climatic Hazards. However, The Relevance Of Their Location In Relation To Those Hazards And Local Ncp Has Hardly Been Addressed. In The Portal (Pathways Of Transformation In The Alps) Project, We Identified And Mapped A Portfolio Of 97 Nbs For Climate Change Adaptation In The European Alps. Most Nbs Addressed Drought Or Soil Instability And Aimed To Provide Multiple Ncp Simultaneously Such As Wood Production And Protective Function Against Landslides. We Analysed Whether Nbs Are Located Where They Are The Most Needed, According To Both Current And Future Intensity Of The Hazards They Aim To Address And To Supply-Flow-Demand Indicators Of The Ncp They Aim To Provide. We Found That The Location Of Nbs Is Not Overall Related To Current Supply-Flow-Demand Indicators Of Most Ncp, Nor To The Intensity Of Hazards. Nevertheless, Nbs Addressing Droughts And Floods Are Located In Areas Where These Hazards Are More Intense, But Do Not Match Higher Values For Ncp Indicators. Conversely, Nbs Aiming To Produce Wood And To Provide Protective Function Against Landslides Are Located In Areas With Greater Levels Of These Ncp, Regardless Of The Intensity Of Hazards. These Results Suggest That Hazards And Ncp Indicators Are Not The Main Drivers Of Nbs Implementation. We Argue That Integrating Local Climate Conditions And Current Ncp Flows Is Needed To Underpin A Macro-Regional Strategy For Planning Nbs Implementation.
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Dumont, M., Gascoin, S., Reeveillet, M., Voisin, D., Tuzet, F., Arnaud, L., et al. (2023). Spatial Variability Of Saharan Dust Deposition Revealed Through A Citizen Science Campaign. Earth System Science Data, 151(7), 3075–3094.
Abstract: Saharan Dust Outbreaks Have Profound Effects On Ecosystems, Climate, Human Health, And The Cryosphere In Europe. However, The Spatial Deposition Pattern Of Saharan Dust Is Poorly Known Due To A Sparse Network Of Ground Measurements. Following The Extreme Dust Deposition Event Of February 2021 Across Europe, A Citizen Science Campaign Was Launched To Sample Dust On Snow Over The Pyrenees And The European Alps. This Somewhat Improvised Campaign Triggered Wide Interest Since 152 Samples Were Collected From The Snow In The Pyrenees, The French Alps, And The Swiss Alps In Less Than 4 Weeks. Among The 152 Samples, 113 In Total Could Be Analysed, Corresponding To 70 Different Locations. The Analysis Of The Samples Showed A Large Variability In The Dust Properties And Amount. We Found A Decrease In The Deposited Mass And Particle Sizes With Distance From The Source Along The Transport Path. This Spatial Trend Was Also Evident In The Elemental Composition Of The Dust As The Iron Mass Fraction Decreased From 11% In The Pyrenees To 2% In The Swiss Alps. At The Local Scale, We Found A Higher Dust Mass On South-Facing Slopes, In Agreement With Estimates From High-Resolution Remote Sensing Data. This Unique Dataset, Which Resulted From The Collaboration Of Several Research Laboratories And Citizens, Is Provided As An Open Dataset To Benefit A Large Community And To Enable Further Scientific Investigations. Data Presented In This Study Are Available At Https://Doi.Org/10.5281/Zenodo.7969515 (Dumont Et Al., 2022A).
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Duvillier, C., Eckert, N., Evin, G., & Deschatres, M. (2023). Development And Evaluation Of A Method To Identify Potential Release Areas Of Snow Avalanches Based On Watershed Delineation. Natural Hazards And Earth System Sciences, 232(4), 1383–1408.
Abstract: Snow Avalanches Are A Prevalent Threat In Mountain Territories. Large-Scale Mapping Of Avalanche-Prone Terrain Is A Prerequisite For Land-Use Planning Where Historical Information About Past Events Is Insufficient. To This Aim, The Most Common Approach Is The Identification Of Potential Release Areas (Pras) Followed By Numerical Avalanche Simulations. Existing Methods For Identifying Pras Rely On Terrain Analysis. Despite Their Efficiency, They Suffer From (I) A Lack Of Systematic Evaluation On The Basis Of Adapted Metrics And Past Observations Over Large Areas And (Ii) A Limited Ability To Distinguish Pras Corresponding To Individual Avalanche Paths. The Latter May Preclude Performing Numerical Simulations Corresponding To Individual Avalanche Events, Questioning The Realism Of Resulting Hazard Assessments. In This Paper, A Method That Accurately Identifies Individual Snow Avalanche Pras Based On Terrain Parameters And Watershed Delineation Is Developed, And Confusion Matrices And Different Scores Are Proposed To Evaluate It. Comparison To An Extensive Cadastre Of Past Avalanche Limits From Different Massifs Of The French Alps Used As Ground Truth Leads To True Positive Rates (Recall) Between 80 % And 87 % In Pra Numbers And Between 92.4 % And 94 % In Pra Areas, Which Shows The Applicability Of The Method To The French Alps Context. A Parametric Study Is Performed, Highlighting The Overall Robustness Of The Approach And The Most Important Steps/Choices To Maximize Pra Detection, Among Which The Important Role Of Watershed Delineation To Identify The Right Number Of Individual Pras Is Highlighted. These Results May Contribute To Better Understanding Avalanche Hazard In The French Alps. Wider Outcomes Include An In-Depth Investigation Of The Issue Of Evaluating Automated Pra Detection Methods And A Large Data Set That Could Be Used For Additional Developments, And To Benchmark Existing And/Or New Pra Detection Methods.
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Eichler, A., Legrand, M., Jenk, T., Preunkert, S., Andersson, C., Eckhardt, S., et al. (2023). Consistent Histories Of Anthropogenic Western European Air Pollution Preserved In Different Alpine Ice Cores. Cryosphere, , 211922–213722.
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Erhardt, T., Jensen, C., Adolphi, F., Kjær, H., Dallmayr, R., Twarloh, B., et al. (2023). High-Resolution Aerosol Data From The Top 3.8 Kyr Of The East Greenland Ice Coring Project (Egrip) Ice Core. Earth System Science Data, 151(111), 5079–5091.
Abstract: Here We Present The High-Resolution Continuous Flow Analysis (Cfa) Data From The Top 479 M Of The East Greenland Ice Coring Project (Egrip) Ice Core Covering The Past 3.8 Kyr. The Data Consist Of 1 Mm Depth-Resolution Profiles Of Calcium, Sodium, Ammonium, Nitrate, And Electrolytic Conductivity As Well As Decadal Averages Of These Profiles. The Nominally 1 Mm Data Represent An Oversampling Of The Record As The True Resolution Is Limited By The Analytical Setup To Approximately 1 Cm. Alongside The Data We Provide A Description Of The Measurement Setup, Procedures, The Relevant References For The Specific Methods As Well As An Assessment Of The Precision Of The Measurements, The Sample-To-Depth Assignment, And The Depth And Temporal Resolution Of The Data Set. The Error In Absolute Depth Assignment Of The Data May Be On The Order Of 2 Cm; However, Relative Depth Offsets Between The Records Of The Individual Species Are Only On The Order Of 1 Mm. The Presented Data Have Sub-Annual Resolution Over The Entire Depth Range And Have Already Formed Part Of The Data For An Annually Layer-Counted Timescale For The Egrip Ice Core Used To Improve And Revise The Multi-Core Greenland Ice-Core Chronology (Gicc05) To A New Version, Gicc21 (Sinnl Et Al., 2022). The Data Are Available In Full 1 Mm Resolution And Decadal Averages On Pangaea (Https://Doi.Org/10.1594/Pangaea.945293, Erhardt Et Al., 2022B).
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Escobar, A., Guillard, F., Einav, I., & Faug, T. (2023). A Scaling Law For The Length Of Granular Jumps Down Smooth Inclines. Journal Of Fluid Mechanics, 9739.
Abstract: Granular Jumps Commonly Develop During Granular Flows Over Complex Topographies Or When Hitting Retaining Structures. While This Process Has Been Well-Studied For Hydraulic Flows, In Granular Flows Such Jumps Remain To Be Fully Explored, Given The Role Of Interparticle Friction. Predicting The Length Of Granular Jumps Is A Challenging Question, Relevant To The Design Of Protection Dams Against Avalanches. In This Study, We Investigate The Canonical Case Of Standing Jumps Formed In Granular Flows Down Smooth Inclines Using Extensive Numerical Simulations Based On The Discrete Element Method. We Consider Both Two- And Three-Dimensional Configurations And Vary The Chute Bottom Friction To Account For The Crucial Interplay Between The Sliding Along The Smooth Bottom And The Shearing Across The Granular Bulk Above. By Doing So, We Derived A Robust Scaling Law For The Jump Length That Is Valid Over A Wide Range Of Froude Numbers And Takes Into Account The Influence Of The Packing Density. The Findings Have Potential Implications On A Number Of Situations Encountered In Industry As Well As Problems Associated With Natural Hazards.
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Faïn, X., Etheridge, D., Fourteau, K., Martinerie, P., Trudinger, C., Rhodes, R., et al. (2023). Southern Hemisphere Atmospheric History Of Carbon Monoxide Over The Late Holocene Reconstructed From Multiple Antarctic Ice Archives. Climate Of The Past, 191(111), 2287–2311.
Abstract: Carbon Monoxide (Co) Is A Naturally Occurring Atmospheric Trace Gas, A Regulated Pollutant, And One Of The Main Components Determining The Oxidative Capacity Of The Atmosphere. Evaluating Climate-Chemistry Models Under Different Conditions Than Today And Constraining Past Co Sources Requires A Reliable Record Of Atmospheric Co Mixing Ratios ([Co]) That Includes Data Since Preindustrial Times. Here, We Report The First Continuous Record Of Atmospheric [Co] For Southern Hemisphere (Sh) High Latitudes Over The Past 3 Millennia. Our Continuous Record Is A Composite Of Three High-Resolution Antarctic Ice Core Gas Records And Firn Air Measurements From Seven Antarctic Locations. The Ice Core Gas [Co] Records Were Measured By Continuous Flow Analysis (Cfa), Using An Optical Feedback Cavity-Enhanced Absorption Spectrometer (Of-Ceas), Achieving Excellent External Precision (2.8-8.8 Ppb; 2 Sigma ) And Consistently Low Blanks (Ranging From 4.1 +/- 1.2 To 7.4 +/- 1.4 Ppb), Thus Enabling Paleo-Atmospheric Interpretations. Six New Firn Air [Co] Antarctic Datasets Collected Between 1993 And 2016 Ce At The De08-2, Dssw19K, Dssw20K, South Pole, Aurora Basin North (Abn), And Lock-In Sites (And One Previously Published Firn Co Dataset At Berkner) Were Used To Reconstruct The Atmospheric History Of Co From Similar To 1897 Ce, Using Inverse Modeling That Incorporates The Influence Of Gas Transport In Firn. Excellent Consistency Was Observed Between The Youngest Ice Core Gas [Co] And The [Co] From The Base Of The Firn And Between The Recent Firn [Co] And Atmospheric [Co] Measurements At Mawson Station (Eastern Antarctica), Yielding A Consistent And Contiguous Record Of Co Across These Different Archives. Our Antarctic [Co] Record Is Relatively Stable From – 835 To 1500 Ce, With Mixing Ratios Within A 30-45 Ppb Range (2 Sigma ). There Is A Similar To 5 Ppb Decrease In [Co] To A Minimum At Around 1700 Ce During The Little Ice Age. Co Mixing Ratios Then Increase Over Time To Reach A Maximum Of Similar To 54 Ppb By Similar To 1985 Ce. Most Of The Industrial Period [Co] Growth Occurred Between About 1940 To 1985 Ce, After Which There Was An Overall [Co] Decrease, As Observed In Greenland Firn Air And Later At Atmospheric Monitoring Sites And Attributed Partly To Reduced Co Emissions From Combustion Sources. Our Antarctic Ice Core Gas Co Observations Differ From Previously Published Records In Two Key Aspects. First, Our Mixing Ratios Are Significantly Lower Than Reported Previously, Suggesting That Previous Studies Underestimated Blank Contributions. Second, Our New Co Record Does Not Show A Maximum In The Late 1800S. The Absence Of A [Co] Peak Around The Turn Of The Century Argues Against There Being A Peak In Southern Hemisphere Biomass Burning At This Time, Which Is In Agreement With (I) Other Paleofire Proxies Such As Ethane Or Acetylene And (Ii) Conclusions Reached By Paleofire Modeling. The Combined Ice Core And Firn Air [Co] History, Spanning – 835 To 1992 Ce, Extended To The Present By The Mawson Atmospheric Record, Provides A Useful Benchmark For Future Atmospheric Chemistry Modeling Studies.
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Farvacque, M., Eckert, N., Candia, G., Bourrier, F., Corona, C., & Toe, D. (2023). Holistic Rockfall Risk Assessment In High Mountain Areas Affected By Seismic Activity: Application To The Uspallata Valley, Central Andes, Chile. Risk Analysis, .
Abstract: Over Large Regions Exposed To Natural Disasters, Cascading Effects Resulting From Complex Or Concatenated Natural Processes May Represent A Large Portion Of Total Risk. Populated High-Mountain Environments Are A Major Concern, And Methods For Large-Scale Quantitative Risk Analyses Are Urgently Required To Improve Risk Mitigation. This Article Presents A Comprehensive Quantitative Rockfall Risk Assessment Over A Large Archetypal Valley Of The Andean Mountains, In Central Chile, Which Integrates A Wide Spectrum Of Elements At Risk. Risk Is Expressed As An Expected Damage Both In Monetary Terms And Casualties, At Different Scales Relevant For Decision Making. Notably, Total Rockfall Risk Is Divided Into Its Main Drivers, Which Allows Quantifying Seismically Induced Rockfall Risk. For This Purpose, The Local Seismic Hazard Is Quantified And The Yield Acceleration, That Is, Acceleration Required To Initiate Rockfall, Is Determined At The Regional Scale. The Probability Of Failure Is Thereafter Derived In Terms Of Annual Frequency Of Rockfall Initiation And Integrated In The Quantitative Risk Assessment (Qra) Process. Our Results Show The Significant Role Of Seismic Activity As The Triggering Mechanism Of Rockfalls, And Highlight Elements At Risk That Have A Major Contribution To The Total Risk. Eventually A Sensitivity Analysis Is Conducted To (I) Assess The Robustness Of Obtained Risk Estimates To The Data And Modeling Choices And (Ii) Identify The Most Influential Assumptions. Our Approach Evidences The Feasibility Of Large-Scale Qras In Sensitive Environments And Opens Perspectives For Refining Qras In Similar Territories Significantly Affected By Cascading Effects And Multihazards.
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Favillier, A., Guillet, S., Lopez-Saez, J., Giacona, F., Eckert, N., Zenhausern, G., et al. (2023). Identifying And Interpreting Regional Signals In Tree-Ring Based Reconstructions Of Snow Avalanche Activity In The Goms Valley (Swiss Alps). Quaternary Science Reviews, .
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Fleischmann, A., Papa, F., Hamilton, S., Fassoni-Andrade, A., Wongchuig, S., Espinoza, J., et al. (2023). Increased Floodplain Inundation In The Amazon Since 1980. Environmental Research Letters, 181(3).
Abstract: Extensive Floodplains Throughout The Amazon Basin Support Important Ecosystem Services And Influence Global Water And Carbon Cycles. A Recent Change In The Hydroclimatic Regime Of The Region, With Increased Rainfall In The Northern Portions Of The Basin, Has Produced Record-Breaking High Water Levels On The Amazon River Mainstem. Yet, The Implications For The Magnitude And Duration Of Floodplain Inundation Across The Basin Remain Unknown. Here We Leverage State-Of-The-Art Hydrological Models, Supported By In-Situ And Remote Sensing Observations, To Show That The Maximum Annual Inundation Extent Along The Central Amazon Increased By 26% Since 1980. We Further Reveal Increased Flood Duration And Greater Connectivity Among Open Water Areas In Multiple Amazon Floodplain Regions. These Changes In The Hydrological Regime Of The World'S Largest River System Have Major Implications For Ecology And Biogeochemistry, And Require Rapid Adaptation By Vulnerable Populations Living Along Amazonian Rivers.
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Fotso-Nguemo, T., Weber, T., Diedhiou, A., Chouto, S., Vondou, D., Rechid, D., et al. (2023). Projected Impact Of Increased Global Warming On Heat Stress And Exposed Population Over Africa. Earths Future, .
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Fremand, A., Fretwell, P., Bodart, J., Pritchard, H., Aitken, A., Bamber, J., et al. (2023). Antarctic Bedmap Data: Findable, Accessible, Interoperable, And Reusable (Fair) Sharing Of 60 Years Of Ice Bed, Surface, And Thickness Data. Earth System Science Data, 151(7), 2695–2710.
Abstract: One Of The Key Components Of This Research Has Been The Mapping Of Antarctic Bed Topography And Ice Thickness Parameters That Are Crucial For Modelling Ice Flow And Hence For Predicting Future Ice Loss And The Ensuing Sea Level Rise. Supported By The Scientific Committee On Antarctic Research (Scar), The Bedmap3 Action Group Aims Not Only To Produce New Gridded Maps Of Ice Thickness And Bed Topography For The International Scientific Community, But Also To Standardize And Make Available All The Geophysical Survey Data Points Used In Producing The Bedmap Gridded Products. Here, We Document The Survey Data Used In The Latest Iteration, Bedmap3, Incorporating And Adding To All Of The Datasets Previously Used For Bedmap1 And Bedmap2, Including Ice Bed, Surface And Thickness Point Data From All Antarctic Geophysical Campaigns Since The 1950S. More Specifically, We Describe The Processes Used To Standardize And Make These And Future Surveys And Gridded Datasets Accessible Under The Findable, Accessible, Interoperable, And Reusable (Fair) Data Principles. With The Goals Of Making The Gridding Process Reproducible And Allowing Scientists To Re-Use The Data Freely For Their Own Analysis, We Introduce The New Scar Bedmap Data Portal (Https://Bedmap.Scar.Org, Last Access: 1 March 2023) Created To Provide Unprecedented Open Access To These Important Datasets Through A Web-Map Interface. We Believe That This Data Release Will Be A Valuable Asset To Antarctic Research And Will Greatly Extend The Life Cycle Of The Data Held Within It. Data Are Available From The Uk Polar Data Centre: Https://Data.Bas.Ac.Uk (Last Access: 5 May 2023 ). See The Data Availability Section For The Complete List Of Datasets.
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Gaetani, M., Ceglar, A., Diedhiou, A., Jerez, S., Rodriguez-Fonseca, B., & Sultan, B. (2023). Editorial: (10 Years) Water-Energy-Food Nexus: Impact Of Climate Variability And Change On The Water-Energy-Food Nexus. Frontiers In Climate, .
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Ghasemi, M., Charrahy, Z., & Gonzalez-Garcia, A. (2023). Mapping Cultural Ecosystem Services Provision: An Integrated Model Of Recreation And Ecotourism Opportunities. Land Use Policy, .
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Gilbert, A., Gimbert, F., Gagliardini, O., & Vincent, C. (2023). Inferring The Basal Friction Law From Long Term Changes Of Glacier Length, Thickness And Velocity On An Alpine Glacier. Geophysical Research Letters, 505(161).
Abstract: Basal Sliding Of Glaciers And Ice Sheets Remains A Source Of Uncertainty In Simulating The Long-Term Evolution Of Ice Masses. In Particular, The Response Of Ice Flow To Changes In Driving Stress Depends Strongly On The Value Of The Exponent M In Nonlinear Friction Laws (E.G., Weertman'S Law), Which Is Poorly Constrained By Observations. Here We Constrain The Friction Law At A Natural Scale On Argentiere Glacier (French Alps, Hard-Bed), Taking Advantage Of Well-Resolved Observations Of Glacier Mass Balance, Geometry And Basal Sliding Over Time Spans That Include Large Changes In Driving Stress. By Combining Three Different Independent Methods Based On (A) Surface Velocity Inversion, (B) Transient Length Change Modeling, And (C) Direct Local Sliding Measurements, We Consistently Find A Value Of M = 3.1 +/- 0.3. We Suggest That Weertman'S Law Is Suitable For Modeling The Long-Term Evolution Of Hard-Bedded Glaciers And Ice Sheets.
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Gilbert, A., Gimbert, F., Gagliardini, O., & Vincent, C. (2023). Inferring The Basal Friction Law From Long Term Changes Of Glacier Length, Thickness And Velocity On An Alpine Glacier. Geophysical Research Letters, 505(161).
Abstract: Basal Sliding Of Glaciers And Ice Sheets Remains A Source Of Uncertainty In Simulating The Long-Term Evolution Of Ice Masses. In Particular, The Response Of Ice Flow To Changes In Driving Stress Depends Strongly On The Value Of The Exponent M In Nonlinear Friction Laws (E.G., Weertman'S Law), Which Is Poorly Constrained By Observations. Here We Constrain The Friction Law At A Natural Scale On Argentiere Glacier (French Alps, Hard-Bed), Taking Advantage Of Well-Resolved Observations Of Glacier Mass Balance, Geometry And Basal Sliding Over Time Spans That Include Large Changes In Driving Stress. By Combining Three Different Independent Methods Based On (A) Surface Velocity Inversion, (B) Transient Length Change Modeling, And (C) Direct Local Sliding Measurements, We Consistently Find A Value Of M = 3.1 +/- 0.3. We Suggest That Weertman'S Law Is Suitable For Modeling The Long-Term Evolution Of Hard-Bedded Glaciers And Ice Sheets.
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Gonzalez, A., Fontaine, F., Barruol, G., Recking, A., Burtin, A., Join, J., et al. (2023). Seismic Signature Of A River Flooding In La R & Prime;Eunion Island During The Tropical Cyclone Dumazile (March 2018). Journal Of Applied Geophysics, 2152.
Abstract: Monitoring Of Sediment Transport During Extreme Flood Events Is Difficult And Often Impossible. Fluvial Seismology Can Provide Constraints On The Mechanisms Of This Transport And On The Seismic Sources But Few Cases Of Application In Context Of Extreme Events Such As Tropical Cyclones Were Realized. Recordings From Three Seismic Stations Temporarily Installed Along A River (The Rivie`Re Du Ma<Sic>T) Located In La Re & Prime;Union Island (Indian Ocean) Are Analysed To Characterize High-Frequency (> 1 Hz) Seismic Noise Induced By The Extreme Flood Generated By The Tropical Cyclone Dumazile (March 2018). We Evidence A Good Correlation (R2 = 0.94) Between The Amplitude Of The Seismic Signal And The Water Level At Lower Frequencies (2-7 Hz), Particularly During The Rising Limb Of The River Flood. The Relationship Between Seismic Amplitude And Water Level Measurements Tested At Multiple Frequency Ranges Are Consistent With A Signal Dominated By Water Flow At Lower Frequencies And By Sediment Transport At Higher Frequencies (15-45 Hz). We Show That The Use Of Seismic Measurement, Particularly At Stations Located Very Close To The Riverbed Can Provide Comprehensive Information On The Mechanisms Involved During Sediment Transport Associated With Extreme Flood Events When Direct Measurements Are Not Possible.
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Gonzalez-Garcia, A., Aguado, M., Solascasas, P., Palomo, I., Gonzalez, J., Garcia-Llorente, M., et al. (2023). Co-Producing An Ecosystem Services-Based Plan For Sustainable University Campuses. Landscape And Urban Planning, 2302.
Abstract: In The Context Of Global Change, Social-Ecological Perspectives For Organisations And Territorial Planning Schemes Are Key To Facilitate A Transition Towards Sustainability. Consequently, Ecosystem Services (Es) Assessment And Mapping Are Being Increasingly Used To Enhance Knowledge Co-Production For More Sustainable Territorial Management. Higher Education Organizations Have The Potential To Catalyse The Sustainability Transition Of So-Ciety, But There Is A Lack Of Studies Integrating Novel And Current Sustainable Development Approaches In Spatial Planning At University Campuses. Here, We Proposed An Integrated Approach For Developing An Ecosystem Services-Based Plan To Manage The Campus Of The Autonomous University Of Madrid (Spain). We Developed A Participatory Process Integrating All The Various Actors And The Decision Making-Bodies Of The University. This Participatory Process Involved Meetings With Different Groups And 2,126 Surveys Administrated To Students, Professors, Researchers And Administration/Services Staff. We Also Developed A Technical Process For Assessing Es Including Eight Es Maps (Four Regulating, One Provisioning And Three Cultural), Consulted With The Experts And Stakeholders Involved, And Built The Final Version Of The Planning Guide Integrating All Perspectives To Promote Es-Based Strategic Lines. Our Results Showed That Es Maps Are Useful For Creating Management Units And For Multi -Scale Analysis. Es Maps Highlighted Important Values Of The Campus, Allowing The Integration Of More Social Actors That Allow A Stronger Participative Process And The Creation Of A Long-Term Planning Scheme. However, We Identified Certain Aspects Of The Es Approach That Hinder Real-World Application, Including Inherent Problems Associated With Shifting Politics.
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Gonzalez-Garcia, A., Aguado, M., Solascasas, P., Palomo, I., Gonzalez, J., Garcia-Llorente, M., et al. (2023). Co-Producing An Ecosystem Services-Based Plan For Sustainable University Campuses. Landscape And Urban Planning, 2302.
Abstract: In The Context Of Global Change, Social-Ecological Perspectives For Organisations And Territorial Planning Schemes Are Key To Facilitate A Transition Towards Sustainability. Consequently, Ecosystem Services (Es) Assessment And Mapping Are Being Increasingly Used To Enhance Knowledge Co-Production For More Sustainable Territorial Management. Higher Education Organizations Have The Potential To Catalyse The Sustainability Transition Of So-Ciety, But There Is A Lack Of Studies Integrating Novel And Current Sustainable Development Approaches In Spatial Planning At University Campuses. Here, We Proposed An Integrated Approach For Developing An Ecosystem Services-Based Plan To Manage The Campus Of The Autonomous University Of Madrid (Spain). We Developed A Participatory Process Integrating All The Various Actors And The Decision Making-Bodies Of The University. This Participatory Process Involved Meetings With Different Groups And 2,126 Surveys Administrated To Students, Professors, Researchers And Administration/Services Staff. We Also Developed A Technical Process For Assessing Es Including Eight Es Maps (Four Regulating, One Provisioning And Three Cultural), Consulted With The Experts And Stakeholders Involved, And Built The Final Version Of The Planning Guide Integrating All Perspectives To Promote Es-Based Strategic Lines. Our Results Showed That Es Maps Are Useful For Creating Management Units And For Multi -Scale Analysis. Es Maps Highlighted Important Values Of The Campus, Allowing The Integration Of More Social Actors That Allow A Stronger Participative Process And The Creation Of A Long-Term Planning Scheme. However, We Identified Certain Aspects Of The Es Approach That Hinder Real-World Application, Including Inherent Problems Associated With Shifting Politics.
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Gonzalez-Garcia, A., Aguado, M., Solascasas, P., Palomo, I., Gonzalez, J., Garcia-Llorente, M., et al. (2023). Co-Producing An Ecosystem Services-Based Plan For Sustainable University Campuses. Landscape And Urban Planning, .
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Goodwin, S., Lapillonne, S., Piton, G., & Chambon, G. (2023). An Sph Study On Viscoplastic Surges Overriding Mobile Beds: The Many Regimes Of Entrainment. Computers & Geosciences, 1811.
Abstract: Flow-Type Landslides Entrain Mobile Bed Material, But The Processes Involved Are Diverse And Require Systematic Study. We Perform Direct Numerical Simulations Using The Open-Source Sph Package Dualsphysics With A Regularized Herschel-Bulkley Rheology. We Then Compare Model Output With Physical Test Data, And Hence Investigate The Effects Of Varying The Bed Yield Stress Tau(Gamma,B) And Bed Depth H(B), Interpreting The Results Using A Newly-Identified Set Of Dimensionless Numbers. Results Reveal Diverse Interaction Regimes Between Surges And Mobile Beds, Including ''Rigid Bed'', ''Lubrication'', ''Shallow Ploughing'', ''Surfing'', ''Plunging'', And ''Deep Ploughing''. Shallow, Borderline-Stable Beds ''Lubricate'' The Surge: Once Destabilized, These Beds Cause Strong Acceleration Of The Combined Flow Front. Deeper Borderline-Stable Beds Allow The Surge Material To ''Plunge'' Downward, Massively Displacing Bed Material Upward And Downstream. For Stabler Beds, ''Ploughing'' And ''Surfing'' Are Associated With Intermediate And High Values Of Tau(Gamma,B), Respectively. In Both Cases, Beds Retard The Surge, With Mobile Dams Forming For ''Ploughing'' Regimes. Across All Regimes Identified, The Influence Of Tau(Gamma,B) Is Non-Monotonic, With Intermediate Values Decelerating The Combined Flow Fronts The Most. Furthermore, The Different Interaction Regimes Exhibit Unique Velocity Profiles. We Develop Phase Diagrams Based On Three Dimensionless Numbers, Demarcating These Regimes.
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Grilli, R., Delsontro, T., Garnier, J., Jacob, F., & Nemery, J. (2023). A Novel High-Resolution In Situ Tool For Studying Carbon Biogeochemical Processes In Aquatic Systems: The Lake Aiguebelette Case Study. Journal Of Geophysical Research-Biogeosciences, 1281(121).
Abstract: Lakes And Reservoirs Are A Significant Source Of Atmospheric Methane (Ch4), With Emissions Comparable To The Largest Global Ch4 Emitters. Understanding The Processes Leading To Such Significant Emissions From Aquatic Systems Is Therefore Of Primary Importance For Producing Accurate Projections Of Emissions In A Changing Climate. In This Work, We Present The First Deployment Of A Novel Membrane Inlet Laser Spectrometer (Mils) For Fast Simultaneous Detection Of Dissolved Ch4, Ethane (C2H6) And The Stable Carbon Isotope Of Methane (Delta 13Ch4). During A 1-Day Field Campaign, We Performed 2D Mapping Of Surface Water Of Lake Aiguebelette (France). Average Dissolved Ch4 Concentrations And Delta 13Ch4 Were 391.9 +/- 156.3 Nmol L-1 And -67.3 +/- 3.4 Parts Per Thousand In The Littoral Area And 169.8 +/- 26.6 Nmol L-1 And -61.5 +/- 3.6 Parts Per Thousand In The Pelagic Area. The Dissolved Ch4 Concentration In The Pelagic Zone Was 50 Times Larger Than The Concentration Expected At Equilibrium With The Atmosphere, Confirming An Oversaturation Of Dissolved Ch4 In Surface Waters Over Shallow And Deep Areas. The Results Suggest The Presence Of Ch4 Sources Less Enriched In 13C In The Littoral Zone (Presumably The Littoral Sediments). The Ch4 Pool Became More Enriched In 13C With Distance From Shore, Suggesting That Oxidation Prevailed Over Epilimnetic Ch4 Production And It Was Further Confirmed By An Isotopic Mass Balance Technique With The High-Resolution Data. This New In Situ Fast Response Sensor Allows One To Obtain Unique High-Resolution And High-Spatial Coverage Data Sets Within A Limited Amount Of Survey Time. This Tool Will Be Useful In The Future For Studying Processes Governing Ch4 Dynamics In Aquatic Systems. High-Resolution Mapping Of Surface Methane And Its Isotopic Signature Enables Accurate Characterization Of Aquatic Systems And Discrimination Of Biochemical Processes At Work. At Lake Aiguebelette, This New In Situ Tool Allowed Us To Conclude That Methane Present At The Surface Comes Mainly From Shallow Littoral Areas, Where Sediments, Which Are A Source Of Methane, Are Closer To The Surface. During Lateral Transport Of Water Masses From The Littoral Zone, The Change In Isotopic Signature Reveals That Methane Oxidation Prevails Over Local In Situ Production. Comparison With Previous Studies Validates The Importance Of High-Resolution Measurements (Particularly To Capture The High Variability In The Littoral Zone) And Showed That Smaller Lakes Experience Stronger Methane Isotopic Signature Changes For A Given Methane Concentration Variation. This Can Be Explained By The Fact That The Smaller Lake Has A Larger Littoral-To-Total Surface Area. This New Tool Will Be Useful In The Nearby Future To Study The Processes Governing Ch4 Dynamics In Aquatic Systems. Fast In Situ Measurements Of Dissolved Methane And Its Stable Carbon Isotopehigh-Spatial Resolution Mapping Of Dissolved Methane And Its Stable Carbon Isotopeimproved Production/Oxidation Process Identification Over Discrete Sampling
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Guilbert, A., Bernard, J., Peyre, H., Costet, N., Hough, I., Seyve, E., et al. (2023). Prenatal And Childhood Exposure To Ambient Air Pollution And Cognitive Function In School-Age Children: Examining Sensitive Windows And Sex-Specific Associations. Environmental Research, 2352.
Abstract: Background: Combined Effect Of Both Prenatal And Early Postnatal Exposure To Ambient Air Pollution On Child Cognition Has Rarely Been Investigated And Periods Of Sensitivity Are Unknown. This Study Explores The Temporal Relationship Between Pre- And Postnatal Exposure To Pm10, Pm2.5, No2 And Child Cognitive Function. Methods: Using Validated Spatiotemporally Resolved Exposure Models, Pre- And Postnatal Daily Pm2.5, Pm10 (Satellite Based, 1 Km Resolution) And No2 (Chemistry-Transport Model, 4 Km Resolution) Concentrations At The Mother'S Residence Were Estimated For 1271 Mother-Child Pairs From The French Eden And Pelagie Cohorts. Scores Representative Of Children'S General, Verbal And Non-Verbal Abilities At 5-6 Years Were Constructed Based On Subscale Scores From The Wppsi-Iii, Wisc-Iv Or Nepsy-Ii Batteries, Using Confirmatory Factor Analysis (Cfa). Associations Of Both Prenatal (First 35 Gestational Weeks) And Postnatal (60 Months After Birth) Exposure To Air Pollutants With Child Cognition Were Explored Using Distributed Lag Non-Linear Models Adjusted For Confounders. Results: Increased Maternal Exposure To Pm10, Pm2.5 And No2, During Sensitive Windows Comprised Between The 15Th And The 33Rd Gestational Weeks, Was Associated With Lower Males' General And Non-Verbal Abilities. Higher Postnatal Exposure To Pm2.5 Between The 35Th And 52Nd Month Of Life Was Associated With Lower Males' General, Verbal And Non-Verbal Abilities. Some Protective Associations Were Punctually Observed For The Very First Gestational Weeks Or Months Of Life For Both Males And Females And The Different Pollutants And Cognitive Scores. Discussion: These Results Suggest Poorer Cognitive Function At 5-6 Years Among Males Following Increased Maternal Exposure To Pm10, Pm2.5 And No2 During Mid-Pregnancy And Child Exposure To Pm2.5 Around 3-4 Years. Apparent Protective Associations Observed Are Unlikely To Be Causal And Might Be Due To Live Birth Selection Bias, Chance Finding Or Residual Confounding.
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Guilbert, A., Hough, I., Seyve, E., Rolland, M., Quentin, J., Slama, R., et al. (2023). Association Of Prenatal And Postnatal Exposures To Warm Or Cold Air Temperatures With Lung Function In Young Infants. Jama Network Open, 6(3).
Abstract: Importance Little Is Known About Long-Term Associations Of Early-Life Exposure To Extreme Temperatures With Child Health And Lung Function. Objectives To Investigate The Association Of Prenatal And Postnatal Heat Or Cold Exposure With Newborn Lung Function And Identify Windows Of Susceptibility. Design, Setting, And Participants This Population-Based Cohort Study (Sepages) Recruited Pregnant Women In France Between July 8, 2014, And July 24, 2017. Data On Temperature Exposure, Lung Function, And Covariates Were Available From 343 Mother-Child Dyads. Data Analysis Was Performed From January 1, 2021, To December 31, 2021. Exposures Mean, Sd, Minimum, And Maximum Temperatures At The Mother-Child'S Residence, Estimated Using A State-Of-The-Art Spatiotemporally Resolved Model. Main Outcomes And Measures Outcome Measures Were Tidal Breathing Analysis And Nitrogen Multiple-Breath Washout Test Measured At 2 Months Of Age. Adjusted Associations Between Both Long-Term (35 Gestational Weeks And First 4 Weeks After Delivery) And Short-Term (7 Days Before Lung Function Test) Exposure To Ambient Temperature And Newborn Lung Function Were Analyzed Using Distributed Lag Nonlinear Models. Results A Total Of 343 Mother-Child Pairs Were Included In The Analyses (Median [Iqr] Maternal Age At Conception, 32 [30.0-35.2] Years; 183 [53%] Male Newborns). A Total Of 246 Mothers And/Or Fathers (72%) Held At Least A Master'S Degree. Among The 160 Female Newborns (47%), Long-Term Heat Exposure (95Th Vs 50Th Percentile Of Mean Temperature) Was Associated With Decreased Functional Residual Capacity (-39.7 Ml; 95% Ci, -68.6 To -10.7Ml For 24 Degrees C Vs 12 Degrees C At Gestational Weeks 20-35 And Weeks 0-4 After Delivery) And Increased Respiratory Rate (28.0/Min; 95% Ci, 4.2-51.9/Min For 24 Degrees C Vs 12 Degrees C At Gestational Weeks 14-35 And Weeks 0-1 After Delivery). Long-Term Cold Exposure (5Th Vs 50Th Percentile Of Mean Temperature) Was Associated With Lower Functional Residual Capacity (-21.9 Ml; 95% Ci, -42.4 To -1.3 Ml For 1 Degrees C Vs 12 Degrees C At Gestational Weeks 15-29), Lower Tidal Volume (-23.8 Ml; 95% Ci, -43.1 To -4.4 Ml For 1 Degrees C Vs 12 Degrees C At Gestationalweeks 14-35 And Weeks 0-4 After Delivery), And Increased Respiratory Rate (45.5/Min; 95% Ci, 10.1-81.0/Min For 1 Degrees C Vs 12 Degrees C At Gestational Weeks 6-35 And Weeks 0-1 After Delivery) In Female Newborns As Well. No Consistent Association Was Observed For Male Newborns Or Short-Term Exposure To Cold Or Heat. Conclusions And Relevance In This Cohort Study, Long-Term Heat And Cold Exposure From The Second Trimester Until 4 Weeks After Birth Was Associated With Newborn Lung Volumes, Especially Among Female Newborns.
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Guillevic, F., Rossi, M., Develle, A., Spadini, L., Martins, J., Arnaud, F., et al. (2023). Pb Dispersion Pathways In Mountain Soils Contaminated By Ancient Mining And Smelting Activities. Applied Geochemistry, 1501.
Abstract: Over The Last Millennia, Mining And Smelting Activities Have Produced Large Amounts Of Mine And Metallurgical Wastes That Remain Enriched In Potentially Toxic Trace Elements (Pte). A Spatial Distribution Of Pb Content Was Coupled To Mineralogical Observations And Single Extraction Tests To Characterise The Pb Contamination Legacy And Pb Dispersion Trajectories In An Ancient Mining And Smelting Site That Has Been Abandoned For Approximatively 200 Years. In The Peisey-Nancroix Pb-Ag Mine (Savoy, France), Extreme Anthropogenic Pb Contamination Is Located Close To The Slag Heaps And Along Ore And Slag Transport Paths. The Contamination Gradient Is Restricted To A Few Hundred Metres Downhill, Down To Background Pb Values. The Pb-Bearing Phases Change Along The Contamination Gradient. The Most Contaminated Soils Contain Significant Amounts Of Galena And Slags That Are More Or Less Weathered Into Pyromorphite And Cerussite. Pb-Bearing Mn (Hydr-)Oxides Are The Most Stable And Ubiquitous Forms Of Pb, Which Proportions Increase Downgradient. Despite The Presence Of Some Stable Pbbearing Phases (Pyromorphite, Pb-Bearing Mn (Hydr-)Oxides), Extraction Tests Indicate That A Small Proportion Of Pb May Still Be Mobile Over Time.
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Guo, L., Li, J., Dehecq, A., Li, Z., Li, X., & Zhu, J. (2023). A New Inventory Of High Mountain Asia Surging Glaciers Derived From Multiple Elevation Datasets Since The 1970S. Earth System Science Data, , 284122–286122.
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Gupta, A., Reverdy, A., Cohard, J., Hector, B., Descloitres, M., Vandervaere, J., et al. (2023). Impact Of Distributed Meteorological Forcing On Simulated Snow Cover And Hydrological Fluxes Over A Mid-Elevation Alpine Micro-Scale Catchment. Hydrology And Earth System Sciences, 272(1), 191–212.
Abstract: From The Micro- To The Mesoscale, Water And Energy Budgets Of Mountainous Catchments Are Largely Driven By Topographic Features Such As Terrain Orientation, Slope, Steepness, And Elevation, Together With Associated Meteorological Forcings Such As Precipitation, Solar Radiation, And Wind Speed. Those Topographic Features Govern The Snow Deposition, Melting, And Transport, Which Further Impacts The Overall Water Cycle. However, This Microscale Variability Is Not Well Represented In Earth System Models Due To Coarse Resolutions. This Study Explores The Impact Of Precipitation, Shortwave Radiation, And Wind Speed On The Water Budget Distribution Over A 15.28 Ha Small, Mid-Elevation (2000-2200 M) Alpine Catchment At Col Du Lautaret (France). The Grass-Dominated Catchment Remains Covered With Snow For 5 To 6 Months Per Year. The Surface-Subsurface Coupled Distributed Hydrological Model Parflow-Clm Is Used At A Very High Resolution (10 M) To Simulate The Impacts On The Water Cycle Of Meteorological Variability At Very Small Spatial And Temporal Scales. These Include 3D Simulations Of Hydrological Fluxes With Spatially Distributed Forcing Of Precipitation, Shortwave Radiation, And Wind Speed Compared To 3D Simulations Of Hydrological Fluxes With Non-Distributed Forcing. Our Precipitation Distribution Method Encapsulates The Spatial Snow Distribution Along With Snow Transport. The Model Simulates The Dynamics And Spatial Variability Of Snow Cover Using The Common Land Model (Clm) Energy Balance Module And Under Different Combinations Of Distributed Forcing. The Resulting Subsurface And Surface Water Transfers Are Computed By The Parflow Module. Distributed Forcing Leads To Spatially Heterogeneous Snow Cover Simulation, Which Becomes Patchy At The End Of The Melt Season And Shows A Good Agreement With The Remote Sensing Images (Mean Bias Error (Mbe) = 0.22). This Asynchronous Melting Results In A Longer Melting Period Compared To The Non-Distributed Forcing, Which Does Not Generate Any Patchiness. Among The Distributed Meteorological Forcings Tested, Precipitation Distribution, Including Snow Transport, Has The Greatest Impact On Spatial Snow Cover (Mbe = 0.06) And Runoff. Shortwave Radiation Distribution Has An Important Impact, Reducing Evapotranspiration As A Function Of The Slope Orientation (Decreasing The Slope Between Observed And Simulated Evapotranspiration From 1.55 To 1.18). For The Primarily East-Facing Catchment Studied Here, Distributing Shortwave Radiation Helps Generate Realistic Timing And Spatial Heterogeneity In The Snowmelt At The Expense Of An Increase In The Mean Bias Error (From 0.06 To 0.22) For All Distributed Forcing Simulations Compared To The Simulation With Only Distributed Precipitation. Distributing Wind Speed In The Energy Balance Calculation Has A More Complex Impact On Our Catchment, As It Accelerates Snowmelt When Meteorological Conditions Are Favorable But Does Not Generate Snow Patches At The End Of Our Test Case. This Shows That Slope- And Aspect-Based Meteorological Distribution Can Improve The Spatio-Temporal Representation Of Snow Cover And Evapotranspiration In Complex Mountain Terrain.
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Gupta, R., Bourrier, F., Acary, V., & Lambert, S. (2023). Bayesian Interface Based Calibration Of A Novel Rockfall Protection Structure Modelled In The Non-Smooth Contact Dynamics Framework. Engineering Structures, 2972.
Abstract: This Article Presents The Development And Calibration Of A Numerical Model Simulating The Response Of A Novel Rockfall Protection Structure Subjected To Localized Dynamic Loading. This Structure Is Made Of Piled-Up Concrete Blocks Interconnected Via Metallic Components Whose Dynamics Response Under Projectile Impact Is Examined Via Real-Scale Experiments. The Corresponding Numerical Model Is Developed In A Python Based Open Source Software Siconos Which Implements The Non-Smooth Contact Dynamics (Nscd) Method. The Geometrical Features And Mechanical Properties Are Incorporated In The Model Via Specific Developments Pertinent To The Modelling Requirements In Siconos. Some Parameters Peculiar To The Numerical Model Are Calibrated Against The Spatial-Temporal Measurements From Two Full-Scale Impact Experiments. The Bayesian Interface Statistical Learning Method Aided By The Polynomial Chaos Expansion Based Meta-Model Of The Nscd Model Is Deployed For The Calibration. The Additional Understanding Of The Model Dynamics Through The Byproducts Of The Meta-Model Is Highlighted. In The End, The Nscd Model Is Successfully Calibrated Against The Spatial-Temporal Response Of The Experimental Structure With More Than 90% Accuracy For Impact Energies Up To 1 Mj.
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Gustin, M., Dunham-Cheatham, S., Allen, N., Choma, N., Johnson, W., Lopez, S., et al. (2023). Observations Of The Chemistry And Concentrations Of Reactive Hg At Locations With Different Ambient Air Chemistry. Science Of The Total Environment, 9049.
Abstract: The Hg Research Community Needs Methods To More Accurately Measure Atmospheric Hg Concentrations And Chemistry. The Reactive Mercury Active System (Rmas) Uses Cation Exchange, Nylon, And Ptfe Membranes To Determine Reactive Mercury (Rm), Gaseous Oxidized Mercury, And Particulate-Bound Mercury (Pbm) Concentrations And Chemistry. New Data For Atlanta, Georgia (Nrgt) Demonstrated That Particulate-Bound Hg Was Dominant And The Chemistry Was Primarily N And S Hg-Ii Compounds. At Great Salt Lake, Utah (Gsl), Rm Was Predominately Pbm, With N=S > Organics > Halogen > O Hg-Ii Compounds. At Guadalupe Mountains National Park, Texas (Gumo), Halogenated Compound Concentrations Were Lowest When Air Interacting With The Site Was Primarily Derived From The Midwest, And Highest When The Air Was Sourced From Mexico. At Amsterdam Island, Southern Indian Ocean, Compounds Were Primarily Halogenated With Some N, S, And Organic Hg-Ii Compounds Potentially Associated With Biological Activity. The Geos-Chem Model Was Applied To See If It Predicted Measurements At Five Field Sites. Model Values Were Higher Than Observations At Gsl, Slightly Lower At Nrgt, And Observations Were An Order Of Magnitude Higher Than Modeled Values For Gumo And Reno, Nevada. In General, Data Collected From 13 Locations Indicated That N, S, And Organic Rm Compounds Were Associated With City And Forest Locations, Halogenated Compounds Were Sourced From The Marine Boundary Layer, And O Compounds Were Associated With Long-Range Transport. Data Being Developed Currently, And In The Past, Suggest There Are Multiple Forms Of Rm That Modelers Must Consider, And Pbm Is An Important Component Of Rm.
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Halas, P., Mouginot, J., De Fleurian, B., & Langebroek, P. (2023). Impact Of Seasonal Fluctuations Of Ice Velocity On Decadal Trends Observed In Southwest Greenland. Remote Sensing Of Environment, 2852.
Abstract: By Tracking The Feature Displacement Between Satellite Images Spaced Approximately One Year Apart, Surface Runoff Has Been Shown To Have A Long-Term Impact On The Average Ice Flow Of A Land-Terminating Sector Of Greenland. In This Study, We Revisit The Multi-Year Trends In Ice Flow By Assessing More Carefully The Impact Of Seasonal Fluctuation In Velocity On The Annual Mean Ice Velocity. We Find That, Depending On The Length And Period Used To Measure Displacement, Seasonal Fluctuations Do Have An Impact On Observed Velocities On Up To 15%, And Can Affect Decadal Trends. Nevertheless, The Magnitude Of This Fluctuation Is Small Enough To Confirm The General Slowdown Observed During The 2000-2012 Period. Between 2012 And 2019, We Find Significant Re-Acceleration Of Low-Lying Glaciers Tongue But Velocity Trends Elsewhere Are Generally Insignificant And Not Spatially Consistent. Finally, We Propose A More Selective Approach To Recovering Velocity Trends Using Satellite Imagery That Involves Using Only Measurements Where The Image Pair Starting Date Is Before Summer, In Order To Have Comparable Measurements For Every Year, Sampling A Melt Season And The Following Winter.
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Haruna, A., Blanchet, J., & Favre, A. (2023). Modeling Intensity-Duration-Frequency Curves For The Whole Range Of Non-Zero Precipitation: A Comparison Of Models. Water Resources Research, .
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Heintzenberg, J., Legrand, M., Gao, Y., Hara, K., Huang, S., Humphries, R., et al. (2023). Spatio-Temporal Distributions Of The Natural Non-Sea-Salt Aerosol Over The Southern Ocean And Coastal Antarctica And Its Potential Source Regions. Tellus Series B-Chemical And Physical Meteorology, 757(1).
Abstract: More Than 40 Years Of Aerosol Data Including Concentrations Of Particle Number And Of Nine Major Ions Collected Over The Southern Ocean And Coastal Stations Have Been Aggregated And Filtered With Back Trajectories To Reduce The Risk Of Influence From Adjacent Continents. That Provided A Rich Dataset Including Latitudinal Distribution And Seasonality Of Physical And Chemical Aerosol Parameters That Allow Insights Into Aerosol Sources Over The Southern Ocean. These Data Together With Statistics Of Back Trajectory Paths Of High (75% Percentile) And Low (25% Percentile) Concentrations Of The Studied Aerosol Parameters Were Used To Identify Potential Source Regions Of The Respective Compounds. For Particle Number Concentrations, Msa, And The Non-Sea-Salt Fractions Of Ca And Potassium The Most Prominent Source Regions Were Found In High Dms-Areas Close To Antarctica, Whereas The Potential Source Regions Of Nh4 And The Non-Sea-Salt Fraction Of Mg Were Located In Part Further North Over The Southern Ocean. These Geographical Differences Would Reflect Differences In The Marine Biota.
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Hellal, J., Lise, B., Annette, B., Aurélie, C., Giulia, C., Simon, C., et al. (2023). Unlocking Secrets Of Microbial Ecotoxicology: Recent Achievements And Future Challenges. Fems Microbiology Ecology, 999(101).
Abstract: Environmental Pollution Is One Of The Main Challenges Faced By Humanity. By Their Ubiquity And Vast Range Of Metabolic Capabilities, Microorganisms Are Affected By Pollution With Consequences On Their Host Organisms And On The Functioning Of Their Environment. They Also Play Key Roles In The Fate Of Pollutants Through The Degradation, Transformation, And Transfer Of Organic Or Inorganic Compounds. Thus, They Are Crucial For The Development Of Nature-Based Solutions To Reduce Pollution And Of Bio-Based Solutions For Environmental Risk Assessment Of Chemicals. At The Intersection Between Microbial Ecology, Toxicology, And Biogeochemistry, Microbial Ecotoxicology Is A Fast-Expanding Research Area Aiming To Decipher The Interactions Between Pollutants And Microorganisms. This Perspective Paper Gives An Overview Of The Main Research Challenges Identified By The Ecotoxicomic Network Within The Emerging One Health Framework And In The Light Of Ongoing Interest In Biological Approaches To Environmental Remediation And Of The Current State Of The Art In Microbial Ecology. We Highlight Prevailing Knowledge Gaps And Pitfalls In Exploring Complex Interactions Among Microorganisms And Their Environment In The Context Of Chemical Pollution And Pinpoint Areas Of Research Where Future Efforts Are Needed. Overview Of The Main Research Challenges At Different Scales For Microbial Ecotoxicology As Identified By The Ecotoxicomic Network In The Light Of The Current State Of The Art.
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Heutte, B., Bergner, N., Beck, I., Angot, H., Dada, L., Quéléver, L., et al. (2023). Measurements Of Aerosol Microphysical And Chemical Properties In The Central Arctic Atmosphere During Mosaic. Scientific Data, 101(1).
Abstract: The Arctic Environment Is Transforming Rapidly Due To Climate Change. Aerosols' Abundance And Physicochemical Characteristics Play A Crucial, Yet Uncertain, Role In These Changes Due To Their Influence On The Surface Energy Budget Through Direct Interaction With Solar Radiation And Indirectly Via Cloud Formation. Importantly, Arctic Aerosol Properties Are Also Changing In Response To Climate Change. Despite Their Importance, Year-Round Measurements Of Their Characteristics Are Sparse In The Arctic And Often Confined To Lower Latitudes At Arctic Land-Based Stations And/Or Short High-Latitude Summertime Campaigns. Here, We Present Unique Aerosol Microphysics And Chemical Composition Datasets Collected During The Year-Long Multidisciplinary Drifting Observatory For The Study Of Arctic Climate (Mosaic) Expedition, In The Central Arctic. These Datasets, Which Include Aerosol Particle Number Concentrations, Size Distributions, Cloud Condensation Nuclei Concentrations, Fluorescent Aerosol Concentrations And Properties, And Aerosol Bulk Chemical Composition (Black Carbon, Sulfate, Nitrate, Ammonium, Chloride, And Organics) Will Serve To Improve Our Understanding Of High-Arctic Aerosol Processes, With Relevance Towards Improved Modelling Of The Future Arctic (And Global) Climate.
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Hill, E., Urruty, B., Reese, R., Garbe, J., Gagliardini, O., Durand, G., et al. (2023). The Stability Of Present-Day Antarctic Grounding Lines – Part 1: No Indication Of Marine Ice Sheet Instability In The Current Geometry. Cryosphere, 171(9), 3739–3759.
Abstract: Theoretical And Numerical Work Has Shown That Under Certain Circumstances Grounding Lines Of Marine-Type Ice Sheets Can Enter Phases Of Irreversible Advance And Retreat Driven By The Marine Ice Sheet Instability (Misi). Instances Of Such Irreversible Retreat Have Been Found In Several Simulations Of The Antarctic Ice Sheet. However, It Has Not Been Assessed Whether The Antarctic Grounding Lines Are Already Undergoing Misi In Their Current Position. Here, We Conduct A Systematic Numerical Stability Analysis Using Three State-Of-The-Art Ice Sheet Models: Ua, Elmer/Ice, And The Parallel Ice Sheet Model (Pism). For The First Two Models, We Construct Steady-State Initial Configurations Whereby The Simulated Grounding Lines Remain At The Observed Present-Day Positions Through Time. The Third Model, Pism, Uses A Spin-Up Procedure And Historical Forcing Such That Its Transient State Is Close To The Observed One. To Assess The Stability Of These Simulated States, We Apply Short-Term Perturbations To Submarine Melting. Our Results Show That The Grounding Lines Around Antarctica Migrate Slightly Away From Their Initial Position While The Perturbation Is Applied, And They Revert Once The Perturbation Is Removed. This Indicates That Present-Day Retreat Of Antarctic Grounding Lines Is Not Yet Irreversible Or Self-Sustained. However, Our Accompanying Paper (Part 2, ) Shows That If The Grounding Lines Retreated Further Inland, Under Present-Day Climate Forcing, It May Lead To The Eventual Irreversible Collapse Of Some Marine Regions Of West Antarctica.
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Hollender, F., Theodoulidis, N., Mariscal, A., Chaudat, T., Steidl, J., & Roumelioti, Z. (2023). The ?Glass Beads? Coupling Solution For Borehole And Posthole Accelerometers: Shaking Table Tests And Field Retrievability. Seismological Research Letters, 949(2), 925–934.
Abstract: Borehole Accelerometers Are Designed To Record Strong Ground Movements At Depth. They Have Become An Important Complement To Surface Accelerometers For Seismic And Earthquake Engineering Applications. Borehole Accelerometers Present Several Imple-Mentation Challenges, Including Their Coupling With The Geological Environment. One Possible Coupling Solution Is The Use Of Small Glass Beads, Which Are Placed Inside The Borehole Casing With The Purpose Of Filling In Any Empty Space Between The Sensor And The Casing Walls. We Carried Out A Test On A Shaking Table, Over A Wide Range Of Peak Ground Accelerations (Pga From 0.17 To 1.64G), Allowing The Comparison Of The Sig-Nals Between A Surface Accelerometer And A Borehole Accelerometer Coupled Through The Glass Beads. These Tests Show That There Is Almost No Difference Between The Surface And Borehole Accelerometer Signals Between 0.5 And 25 Hz, And Only Very Small Differences Outside This Band (0.2-0.5 Hz And 25-80 Hz). Furthermore, Experience From Multiple Ver-Tical Accelerometric Arrays Show That An Installation Using Glass Beads Is “Reversible”, That Is, 30 Yr After The Initial Installation It Can Still Be Possible To Easily Extract The Acceler-Ometers For Repair Or Replacement, Without Any Problems Or Damage To The Sensors.
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Houngnibo, M., Ali, A., Agali, A., Waongo, M., Lawin, A., & Cohard, J. (2023). Stochastic Disaggregation Of Seasonal Precipitation Forecasts Of The West African Regional Climate Outlook Forum. International Journal Of Climatology, .
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Houphlet, S., Dusseux, P., Adiko, A., Konan-Waidhet, A., Munoz, F., Bigot, S., et al. (2023). Object-Based Characterization Of Vegetation Heterogeneity With Sentinel Images Proves Efficient In A Highly Human-Influenced National Park Of Cote D'Ivoire. Environmental Monitoring And Assessment, 1951(1).
Abstract: Forest Monitoring Requires More Automated Systems To Analyze High Ecosystem Heterogeneity. The Traditional Pixel-Based Detection Method Has Proven To Be Less And Less Effective. A Novel Change Detection Method Is Therefore Proposed To Detect Changes In Forest Cover Using Satellite Images At Very High Spatial Resolution. This Is Object-Oriented Classification, Which Groups Pixels Into Interpreted Objects, Based On Their Spectral Values, Spatial, And Textural Properties. Using Sentinel And Lansat Images, We Tested For The First Time In The West African Rainforest Zone The Effectiveness Of This Method For Better Detection, Delineation, And Analysis Of Land Use And Occupation Types. The Mean Shift Algorithm Was Used In Both The Segmentation And Classification Processes. Next, We Compared The Proposed Object-Oriented Method With A Pixel-Based Image Classification Detection Method By Implementing Both Methods Under The Same Conditions. High Detection Accuracy (> 90%) And An Overall Kappa Greater Than 0.90 Were Obtained By The Object-Oriented Method, Which Is About 20% Higher Than The Pixel-Based Method. The Object-Based Method Was Free Of Salt And Pepper Effects And Was Less Prone To Image Misregistration In Terms Of Change Detection Accuracy And Mapping Results. This Study Demonstrates That The Object-Based Classifier Is A Much Better Approach Than The Classical Pixel-Based Classifier. In Addition, It Shows The Problems Of Detecting Heterogeneous Landscapes And Explains The Observed Confusions Between The Types Of Vegetation Formations Specific To Tropical Wetlands. The Results Obtained Are Encouraging And The Contribution Of High-Resolution Images And The Object-Based Method To Better Discrimination Of Tropical Wetland Vegetation Is Discussed.
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Hutchinson, K., Deshayes, J., Ethe, C., Rousset, C., De Lavergne, C., Vancoppenolle, M., et al. (2023). Improving Antarctic Bottom Water Precursors In Nemo For Climate Applications. Geoscientific Model Development, , 362933–365033.
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Jacobs, S., Kelemen, E., O'Farrell, P., Martin, A., Schaafsma, M., Dendoncker, N., et al. (2023). The Pitfalls Of Plural Valuation. Current Opinion In Environmental Sustainability, 646.
Abstract: This Paper Critically Examines The Current Political Context In Which Valuation Studies Of Nature Are Undertaken. It Challenges The Belief That Somehow, More And Technically Better Valuation Will Drive The Societal Change Toward More Just And Sustainable Futures. Instead, We Argue That Current And Proposed Valuation Practices Risk To Continue To Overrepresent The Values Of Those Who Hold Power And Dominate The Valuation Space, And To Perpetuate The Discrimination Of The Views And Values Of Nondominant Stakeholders. In Tackling This Politically Sensitive Issue, We Define A Political Typology Of Valuations, Making Explicit The Roles Of Power And Discrimination. This Is Done To Provide Valuation Professionals And Other Actors With A Simple Framework To Determine If Valuation Actions And Activities Are Constructive, Inclusive, Resolve Injustices And Enable Systemic Change, Or Rather Entrench The Status Quo Or Aggravate Existing Injustices. The Objective Is To Buttress Actors In Their Decisions To Support, Accept, Improve, Oppose, Or Reject Such Valuations.
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Jenkins, J., Paiement, A., Ourmieres, Y., Le Sommer, J., Verron, J., Ubelmann, C., et al. (2023). A Dnn Framework For Learning Lagrangian Drift With Uncertainty. Applied Intelligence, .
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Jomelli, V., Wagnon, P., Swingedouw, D., Charton, J., Braucher, R., Hue, A., et al. (2023). Unraveling The Climate Control On Debris-Free Glacier Evolution In The Everest Region (Nepal, Central Himalaya) During The Holocene. Quaternary Science Reviews, .
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Jones, N., Strozzi, T., Rabatel, A., Ducasse, E., & Mouginot, J. (2023). Surface Instability Mapping In Alpine Paraglacial Environments Using Sentinel-1 Dinsar Techniques. Ieee Journal Of Selected Topics In Applied Earth Observations And Remote Sensing, 161, 45.
Abstract: Current Climate Warming Leads To Widespread Glacier Shrinkage In High Alpine Terrains And Associated Changes In Surface Dynamics Of Deglacierized Environments. In Consequence, Slope Instabilities Increasingly Develop Along Retreating Glaciers Through Debuttressing Effects Or Degrading Permafrost Conditions. In The Context Of Associated Hazards To The Local Environment And Infrastructure, A Thorough Analysis Of Slope Instabilities Is Highly Relevant. Affected Regions Are Mostly Inaccessible And Cover Large Areas, Therefore Remote Sensing Techniques Such As Differential Interferometric Synthetic Aperture Radar (Dinsar) Are Valuable Tools To Monitor Surface Movements And Assess Their Evolution. We Apply Standard And Advanced Dinsar Methods Using Sentinel-1 Sar Data From 2015 Until Late 2021 To Map And Classify Slope Instabilities In Three Glacierized Regions In The European Alps. The Final Products Include An Inventory Per Region, With A Total Of 815 Mapped Slope Instabilities, Of Which 38% Move <3, 9% Move 3-10, 42% Move 10-30, And 11% Move >30 Cm/Yr. An Additional Assessment Of Four Landslides Occurring Along Shrinking Glaciers Shows Time Series With Recent Accelerations In 2018/19. Validation Of Sentinel-1 Derived Slope Movement Products Is Performed By Comparison With Shorter Wavelength Terrasar-X And Optical Sentinel-2 Derived Data Using Offset Tracking. Results Clearly Show The Suitability Of Sentinel-1 Dinsar Methods To Detect A Range Of Slope Movements In High Alpine Terrain, Yet Also Highlight The Limitations. We Therefore Recommend A Combination Of Advanced Sentinel-1 Dinsar And Sentinel-2 Offset Tracking Methods To Develop A Comprehensive Inventory Of Alpine Slope Motion.
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Jourdain, B., Vincent, C., Réveillet, M., Rabatel, A., Brun, F., Six, D., et al. (2023). A Method To Estimate Surface Mass-Balance In Glacier Accumulation Areas Based On Digital Elevation Models And Submergence Velocities. Journal Of Glaciology, 696(2772), 1403–1418.
Abstract: Measuring Surface Mass-Balance In The Accumulation Areas Of Glaciers Is Challenging Because Of The High Spatial Variability Of Snow Accumulation And The Difficulty Of Conducting Annual Field Glaciological Measurements. Here, We Propose A Method That Can Solve Both These Problems For Many Locations. Ground-Penetrating Radar Measurements And Firn Cores Extracted From A Site In The French Alps Were First Used To Reconstruct The Topography Of A Buried End-Of-Summer Snow Horizon From A Past Year. Using These Data And Surface Elevation Observations From Lidar And Global Navigation Satellite System Instruments, We Calculated The Submergence Velocities Over The Period Between The Buried Horizon And More Recent Surface Elevation Observations. The Differences Between The Changes In Surface Elevation And The Submergence Velocities Were Then Used To Calculate The Annual Surface Mass-Balances With An Accuracy Of +/- 0.34 M W.E. Assuming That The Submergence Velocities Remain Stable Over Several Years, The Surface Mass-Balance Can Be Reconstructed For Subsequent Years From The Differences In Surface Elevation Alone. As Opposed To The Glaciological Method That Requires Substantial Fieldwork Year After Year To Provide Only Point Observations, This Method, Once Submergence Velocities Have Been Calculated, Requires Only Remote-Sensing Data To Provide Spatially Distributed Annual Mass-Balances In Accumulation Areas.
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Kern, H., Jomelli, V., Eckert, N., Grancher, D., Deschatres, M., & Arnaud-Fassetta, G. (2023). Influence Of Snow And Meteorological Conditions On Snow-Avalanche Deposit Volumes And Consequences For Road-Network Vulnerability. Land Degradation & Development, .
Abstract: Snow Avalanches Are A Major Component Of The Mountain Cryosphere That Frequently Create Road Obstructions. Deposit Characteristics Determine The Extent Of Damage To The Road Infrastructures And The Period Of Disruption Of The Road Network, But The Factors Controlling Snow-Deposit Volumes Remain Largely Unknown. This Study Investigates The Influence Of Meteorological And Snowpack Conditions On Snow-Avalanche Deposits And Road-Network Vulnerability Based On 1986 Deposit Volumes From 182 Paths Located In Two Regions Of The French Alps Between 2003 And 2017: The Guil And Haute-Maurienne Valleys. During The Period, 195 Avalanches Impacted The Road Network In These Areas, Leading To Major Disruptions. In The Haute-Maurienne, Correlations Between Deposit Volumes And Meteorological And Snowpack Conditions Are High In Winter. However, The Relationships Differ With Path Elevation And Orientation. Results Do Not Show Any Significant Relationship Between Volumes And Meteorological Or Snowpack Conditions For The Spring Season. Focusing On Deposits That Disturbed The Road Network In Winter And Spring Reveals A Distinct Influence Of Meteorological And Snow Variables Compared To The Overall Dataset, With Snowfall Intensity As The Predominant Control Variable Of Deposit Volumes Leading To Road Cuts. When The Same Analysis Is Conducted By Considering Guil Valley Separately Or By Aggregating The Haute-Maurienne With Guil Valley Area Data, Results Do Not Show Any Significant Relationship, Highlighting The Specific Local Nature Of Relations Between Deposit Volumes And Meteorological And Snowpack Conditions.
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Klein, C., Hanchen, L., Potter, E., Junquas, C., Harris, B., & Maussion, F. (2023). Untangling The Importance Of Dynamic And Thermodynamic Drivers For Wet And Dry Spells Across The Tropical Andes. Environmental Research Letters, 181(3).
Abstract: Andean Vegetation And Agriculture Depend On The Patterns Of Rainfall During The South American Monsoon. However, Our Understanding On The Importance Of Dynamic (Upper-Level Wind Circulation) As Compared To Thermodynamic (Amazon Basin Moisture) Drivers For Andes Rainfall Remains Limited. This Study Examines The Effect Of These Drivers On 3-7 Day Wet And Dry Spells Across The Tropical Andes And Assesses Resulting Impacts On Vegetation. Using Reanalysis And Remote Sensing Data From 1985-2018, We Find That Both Dynamic And Thermodynamic Drivers Play A Role In Determining The Rainfall Patterns. Notably, We Show That The Upper-Level Wind Is An Important Driver Of Rainfall Across The Entire Tropical Andes Mountain Range, But Not In The Amazon Lowlands, Suggesting A Crucial Role Of Topography In This Relationship. From Thermodynamic Perspective, We Find Wet Spell Conditions To Be Associated With Increased Moisture Along The Andes' Eastern Foothills Accompanied By A Strengthened South American Low-Level Jet, With Moisture Lifted Into The Andes Via Topography And Convection For All Considered Regions. Our Results Suggest That While Changes In Amazon Basin Moisture Dominate Rainfall Changes On Daily Time Scales Associated With Three Day Spells, Upper-Level Dynamics Play A More Important Role On The Synoptic Time Scale Of 5-7 Day Spells. Considering Impacts On The Ground, We Find That Only 5-7 Day Spells In The Semi-Arid Andes Have A Prolonged Effect On Vegetation. Our Study Emphasizes The Need To Consider Both Dynamic And Thermodynamic Drivers When Estimating Rainfall Changes In The Tropical Andes, Including In The Context Of Future Climate Projections.
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Kleindienst, A., Zivkovic, I., Tessier, E., Koenig, A., Heimbürger-Boavida, L., Horvat, M., et al. (2023). Assessing Comparability And Uncertainty Of Analytical Methods For Methylated Mercury Species In Seawater. Analytica Chimica Acta, 12781.
Abstract: Background: The Relative Distribution And Importance Of Monomethylmercury (Mmhg) And Dimethylmercury (Dmhg) In Seawater Is Still Under Debate. A Lack Of Comparability Between Measurements At Sub-Picomolar Levels Hampered The Further Understanding Of The Biogeochemical Hg Cycle. To Overcome This, We Assessed The Relative Standard Measurement Uncertainties (U-Ex,U-R) For Direct Measurements Of Mmhg And Dmhg By Species-Specific Isotope Dilution Icp-Ms And Cryo-Focusing Gc-Icp-Ms At Femtomolar Concentrations. Furthermore, U-Ex,U-R Was Determined For The Indirect Determination Of Dmhg (Dmhgcalc = Mehg – Mmhg) And Mehg (Mehgcalc = Mmhg + Dmhg) To Compare The Two Methodologies.Results: Expanded U-Ex,U-R (Confidence Interval Of 95%) For Cryo-Focusing Gc-Icp-Ms Was 14.4 (<50 Fm) And 14.2% (>50 Fm) And For Ss-Id Gc-Icp-Ms 5.6 (<50 Fm) And 3.7% (>50 Fm). For Concentrations Above 50 Fm, U-Ex,U-R For Dmhgcalc Was Always Lower Than For Direct Measurements (14.2%). For Mehgcalc, On The Other Hand, U-Ex,U-R Was Always Higher For Concentrations Above 115 Fm (Range: 3.7-13.9%) Than For Direct Measurements (3.7%). We Evaluated The Comparability Of Directly Measured And Calculated Dmhg And Mehg Concentrations Based On Hg Speciation Measurements For Two Vertical Profiles In The Mediterranean Sea. We Show That Directly Measured And Indirectly Determined Dmhg And Mehg Concentrations Yield Comparable Results.Significance: Our Results Validate The Application Of The Indirect Method For The Determination Of Dmhg If A Direct Measurement Method With A Low U-Ex,U-R Such As Isotope Dilution Is Used For Mmhg And Mehg Measurements. The Validation Of The Indirect Measurement Approach Opens New Possibilities To Generate More Precise And Accurate Dmhg Data In The Global Ocean.
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Klotz, S., Le Bouteiller, C., Mathys, N., Fontaine, F., Ravanat, X., Olivier, J., et al. (2023). A High-Frequency, Long-Term Data Set Of Hydrology And Sediment Yield: Thealpine Badland Catchments Of Draix-Bléone Observatory. Earth System Science Data, 151(101), 4371–4388.
Abstract: Draix-Bleone Critical Zone Observatory Was Created In 1983 To Study Erosion Processes In A Mountainous Badland Region Of The French Southern Alps. Six Catchments Of Varying Size (0.001 To 22 Km(2)) And Vegetation Cover Are Equipped To Measure Water And Sediment Fluxes, Both As Bedload And Suspended Load. This Paper Presents The Core Dataset Of The Observatory, Including Rainfall And Meteorology, High-Frequency Discharge And Suspended-Sediment Concentration, And Event-Scale Bedload Volumes. The Longest Records Span Almost 40 Years. Measurement And Data-Processing Methods Are Presented, As Well As Data Quality Assessment Procedures And Examples Of Results. All The Data Presented In This Paper Are Available On The Open Repository 10.17180/Obs.Draix (Draix-Bleone Observatory, 2015), And A 5-Year Snapshot Is Available For Review At 10.57745/Beyqfq (Klotz Et Al., 2023).
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Knuth, F., Shean, D., Bhushan, S., Schwat, E., Alexandrov, O., Mcneil, C., et al. (2023). Historical Structure From Motion (Hsfm): Automated Processing Of Historical Aerial Photographs For Long-Term Topographic Change Analysis. Remote Sensing Of Environment, 2852.
Abstract: Precisely Measuring The Earth'S Changing Surface On Decadal To Centennial Time Scales Is Critical For Many Science And Engineering Applications, Yet Long-Term Records Of Quantitative Landscape Change Are Often Temporally And Geographically Sparse. Archives Of Scanned Historical Aerial Photographs Provide An Opportunity To Augment These Records With Accurate Elevation Measurements That Capture The Historical State Of The Earth Surface. Structure From Motion (Sfm) Photogrammetry Workflows Produce High-Quality Digital Elevation Models (Dems) And Orthoimage Mosaics From These Historical Images, But Time-Intensive Tasks Like Manual Image Preprocessing (E.G., Fiducial Marker Identification) And Ground Control Point (Gcp) Selection Impede Processing At Scale. We Developed An Automated Method To Process Historical Images And Generate Self-Consistent Time Series Of High-Resolution (0.5-2 M) Dems And Orthomosaics, Without Manual Gcp Selection. The Method Relies On Sfm To Correct Camera Interior And Exterior Orientation And A Robust Multi-Stage Co-Registration Approach Using Modern Reference Terrain Datasets For Geolocation Refinement. We Demonstrate The Method Using Scanned Images From The North American Glacier Aerial Photography (Nagap) Archive Collected Between 1967 And 1997. We Present Results For Two Sites With Variable Photo Acquisition Geometry And Overlap – Mount Baker And South Cascade Glacier In Washington State, Usa. The Automated Method Corrects Initial Camera Position Errors Of Several Kilometers And Produces Accurately Georeferenced, High-Resolution Dems And Orthoimages, Regardless Of Camera Configuration, Acquisition Geometry, Terrain Characteristics, And Reference Dem Properties. The Average Rms Reprojection Error Following Bundle Adjustment Optimization Was 0.67 Px (0.15 M) For The 261 Images Contributing To 10 Final Dem Mosaics Between 1970 And 1992 At Mount Baker, And 0.65 Px (0.13 M) For The 243 Images Contributing To 18 Individual Dems Between 1967 And 1997 At South Cascade Glacier. The Relative Accuracy Of Elevation Values In The Historical Time Series Stacks Was 0.68 M At Mount Baker And 0.37 M At South Cascade Glacier. Our Products Have Reduced Systematic Error And Improved Accuracy Compared To Dem Products Generated Using Sfm With Manual Gcp Selection. Final Elevation Change Measurement Precision Was Similar To 0.7-1.0 M Over A 30-Year Period, Enabling The Study Of Processes With Rates As Low As Similar To 1-3 Cm/Yr. Our Results Demonstrate The Potential Of This Scalable Method To Rapidly Process Archives Of Historical Imagery And Deliver New Quantitative Insights On Long-Term Geodetic Change And Earth Surface Processes.
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Kochtitzky, W., Copland, L., King, M., Hugonnet, R., Jiskoot, H., Morlighem, M., et al. (2023). Closing Greenland'S Mass Balance: Frontal Ablation Of Every Greenlandic Glacier From 2000 To 2020. Geophysical Research Letters, 505(171).
Abstract: In Greenland, 87% Of The Glacierized Area Terminates In The Ocean, But Mass Lost At The Ice-Ocean Interface, Or Frontal Ablation, Has Not Yet Been Fully Quantified. Using Measurements And Models We Calculate Frontal Ablation Of Greenland'S 213 Outlet And 537 Peripheral Glaciers And Find A Total Frontal Ablation Of 481.8 +/- 24.0 For 2000-2010 And 510.2 +/- 18.6 Gt A(-1) For 2010-2020. Ice Discharge Accounted For Similar To 90% Of Frontal Ablation During Both Periods, While Mass Loss Due To Terminus Retreat Comprised The Remainder. Only 16 Glaciers Were Responsible For The Majority (>50%) Of Frontal Ablation From 2010 To 2020. These Estimates, Along With The Climatic-Basal Balance, Allow For A More Complete Accounting Of Greenland Ice Sheet And Peripheral Glacier Mass Balance. In Total, Greenland Accounted For Similar To 90% Of Northern Hemisphere Frontal Ablation For 2000-2010 And 2010-2020.
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Koenig, A., Magand, O., Rose, C., Di Muro, A., Miyazaki, Y., Colomb, A., et al. (2023). Observed In-Plume Gaseous Elemental Mercury Depletion Suggests Significant Mercury Scavenging By Volcanic Aerosols. Environmental Science-Atmospheres, .
Abstract: Terrestrial Volcanism Is Known To Emit Mercury (Hg) Into The Atmosphere. However, Despite Many Years Of Investigation, Its Net Impact On The Atmospheric Hg Budget Remains Insufficiently Constrained, In Part Because The Transformations Of Hg In Volcanic Plumes As They Age And Mix With Background Air Are Poorly Understood. Here We Report The Observation Of Complete Gaseous Elemental Mercury (Gem) Depletion Events In Dilute And Moderately Aged (& Sim;3-7 Hours) Volcanic Plumes From Piton De La Fournaise On Reunion Island. While It Has Been Suggested That Co-Emitted Bromine Could, Once Photochemically Activated, Deplete Gem In A Volcanic Plume, We Measured Low Bromine Concentrations In Both The Gas- And Particle-Phase And Observed Complete Gem Depletion Even Before Sunrise, Ruling Out A Leading Role Of Bromine Chemistry Here. Instead, We Hypothesize That The Gem Depletions Were Mainly Caused By Gas-Particle Interactions With Sulfate-Rich Volcanic Particles (Mostly Of Submicron Size), Abundantly Present In The Dilute Plume. We Consider Heterogeneous Gem Oxidation And Gem Uptake By Particles As Plausible Manifestations Of Such A Process And Derive Empirical Rate Constants. By Extrapolation, We Estimate That Volcanic Aerosols May Scavenge 210 Mg Y(-1) (67-480 Mg Y(-1)) Of Hg From The Atmosphere Globally, Acting Effectively As Atmospheric Mercury Sink. While This Estimate Is Subject To Large Uncertainties, It Highlights That Hg Transformations In Aging Volcanic Plumes Must Be Better Understood To Determine The Net Impact Of Volcanism On The Atmospheric Hg Budget And Hg Deposition Pathways.
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Koenig, A., Magand, O., Verreyken, B., Brioude, J., Amelynck, C., Schoon, N., et al. (2023). Mercury In The Free Troposphere And Bidirectional Atmosphere-Vegetation Exchanges – Insights From Maido Mountain Observatory In The Southern Hemisphere Tropics. Atmospheric Chemistry And Physics, 232(2), 1309–1328.
Abstract: Atmospheric Mercury (Hg) Observations In The Lower Free Troposphere (Lft) Can Give Important Insights Into Hg Redox Chemistry And Can Help Constrain Hg Background Concentrations On A Regional Level. Relatively Continuous Sampling Of Lft Air, Inaccessible To Most Ground-Based Stations, Can Be Achieved At Highaltitude Observatories. However, Such High-Altitude Observatories Are Rare, Especially In The Southern Hemisphere (Sh), And Atmospheric Hg In The Sh Lft Is Unconstrained. To Fill This Gap, We Continuously Measured Gaseous Elemental Mercury (Gem; Hourly) And Reactive Mercury (Rm; Integrated Over Similar To 6-14 D) For 9 Months At Maido Mountain Observatory (2160Ma.S.L.) On Remote Reunion Island (21.1 Degrees S, 55.5 Degrees E) In The Tropical Indian Ocean. Gem Exhibits A Marked Diurnal Variation Characterized By A Midday Peak (Mean: 0.95 Ngm(-3); Sd: 0.08 Ngm(-3)) And A Nighttime Low (Mean: 0.78 Ngm(-3); Sd: 0.11 Ngm(-3)). We Find That This Diurnal Variation Is Likely Driven By The Interplay Of Important Gem Photo-Reemission From The Islands' Vegetated Surfaces (I.E. Vegetation C Soil) During Daylight Hours (8-22 Ngm(-2) H(-1)), Boundary Layer Influences During The Day, And Predominant Lft Influences At Night. We Estimate Gem In The Lft Based On Nighttime Observations In Particularly Dry Air Masses And Find A Notable Seasonal Variation, With Lft Gem Being Lowest From December To March (Mean 0.66 Ngm 3; Sd: 0.07 Ngm 3) And Highest From September To November (Mean: 0.79 Ng M(-3); Sd: 0.09 Ng M(-3)). Such A Clear Gem Seasonality Contrasts With The Weak Seasonal Variation Reported For The Sh Marine Boundary Layer But Is In Line With Modeling Results, Highlighting The Added Value Of Continuous Hg Observations In The Lft. Maido Rm Is 10.6 Pg M(-3) (Sd: 5.9 Pg M(-3)) On Average, But Rm In The Cloud-Free Lft Might Be About Twice As High, As Weekly-Biweekly Sampled Rm Observations Are Likely Diluted By Low-Rm Contributions From The Boundary Layer And Clouds.
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Kokhanovsky, A., Brell, M., Segl, K., Bianchini, G., Lanconelli, C., Lupi, A., et al. (2023). First Retrievals Of Surface And Atmospheric Properties Using Enmap Measurements Over Antarctica. Remote Sensing, .
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Konate, D., Didi, S., Dje, K., Diedhiou, A., Kouassi, K., Kamagate, B., et al. (2023). Observed Changes In Rainfall And Characteristics Of Extreme Events In Cote D'Ivoire (West Africa). Hydrology, .
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Kondi-Akara, G., Hingray, B., Francois, B., & Diedhiou, A. (2023). Recent Trends In Urban Electricity Consumption For Cooling In West And Central African Countries. Energy, .
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Kopp, R., Oppenheimer, M., O'Reilly, J., Drijfhout, S., Edwards, T., Fox-Kemper, B., et al. (2023). Communicating Future Sea-Level Rise Uncertainty And Ambiguity To Assessment Users. Nature Climate Change, .
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Lalande, M., Ménégoz, M., Krinner, G., Ottlé, C., & Cheruy, F. (2023). Improving Climate Model Skill Over High Mountain Asia By Adapting Snow Cover Parameterization To Complex-Topography Areas. Cryosphere, 171(121), 5095–5130.
Abstract: This Study Investigates The Impact Of Topography On Five Snow Cover Fraction (Scf) Parameterizations Developed For Global Climate Models (Gcms), Including Two Novel Ones. The Parameterization Skill Is First Assessed With The High Mountain Asia Snow Reanalysis (Hmasr), And Three Of Them Are Implemented In The Orchidee Land Surface Model (Lsm) And Tested In Global Land-Atmosphere Coupled Simulations. Hmasr Includes Snow Depth (Sd) Uncertainties, Which May Be Due To The Elevation Differences Between In Situ Stations And Hmasr Grid Cells. Nevertheless, The Scf-Sd Relationship Varies Greatly Between Mountainous And Flat Areas In Hmasr, Especially During The Snow-Melting Period. The New Parameterizations That Include A Dependency On The Subgrid Topography Allow A Significant Scf Bias Reduction, Reaching 5 % To 10 % On Average In The Global Simulations Over Mountainous Areas, Which In Turn Leads To A Reduction Of The Surface Cold Bias From – 1.8 Circle C To About – 1 Circle C In High Mountain Asia (Hma). Furthermore, The Seasonal Hysteresis Between Scf And Sd Found In Hmasr Is Better Captured In The Parameterizations That Split The Accumulation And The Depletion Curves Or That Include A Dependency On The Snow Density. The Deep-Learning Scf Parameterization Is Promising But Exhibits More Resolution-Dependent And Region-Dependent Features. Persistent Snow Cover Biases Remain In Global Land-Atmosphere Experiments. This Suggests That Other Model Biases May Be Intertwined With The Snow Biases And Points Out The Need To Continue Improving Snow Models And Their Calibration. Increasing The Model Resolution Does Not Consistently Reduce The Simulated Scf Biases, Although Biases Get Narrower Around Mountain Areas. This Study Highlights The Complexity Of Calibrating Scf Parameterizations Since They Affect Various Land-Atmosphere Feedbacks. In Summary, This Research Spots The Importance Of Considering Topography In Scf Parameterizations And The Challenges In Accurately Representing Snow Cover In Mountainous Regions. It Calls For Further Efforts To Improve The Representation Of Subgrid-Scale Processes Affecting Snowpack In Climate Models.
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Lamare, M., Domine, F., Revuelto, J., Pelletier, M., Arnaud, L., & Picard, G. (2023). Investigating The Role Of Shrub Height And Topography In Snow Accumulation On Low-Arctic Tundra Using Uav-Borne Lidar. Journal Of Hydrometeorology, , 83588–85388.
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Lambert, S., Bourrier, F., Ceron-Mayo, A., Dugelas, L., Dubois, F., & Piton, G. (2023). Small-Scale Modeling Of Flexible Barriers. I: Mechanical Similitude Of The Structure. Journal Of Hydraulic Engineering, 1491(3).
Abstract: Flexible Barriers Can Be Used To Trap Woody Debris Or Debris Flows. However, Their Small Scale Modelling Is Challenging Because Of Their Possible Deformation. This Article Addresses How To Meet The Partial Mechanical Similitude Of Manufactured Flexible Barriers. Relevant Dimensionless Parameters Are Defined From Flow Velocity, Barrier Geometry, And Component Mechanical Properties. These Similitude Criteria Are Validated Using Numerical Simulations Of Barriers Exposed To A Hydrodynamic Loading At Various Scales. The Simulations Also Confirm The Importance Of Accounting For The Mechanical Characteristics Of The Barrier Components When Designing Model Barriers In View Of Achieving Realistic Deformations. Next, A Real Barrier With Complex Features Is Scaled To Conduct Flume Experiments. This Scaled Barrier Is 3D-Printed With Material Selected To Achieve The Mechanical Similitude Criterion. Another Validation Of This Approach Is Performed Considering Hydrostatic Loading And Checking That Simulated And Measured Deformations Are Similar. As An Application Case, The Deformations Measured During The Experiments Performed With Woody Debris Are Also Compared To The Hydrostatic Loading.
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Lambert, S., Fontaine, F., & Piton, G. (2023). Flexible Barrier And Flow-Driven Woody Debris: An Experimental Investigation Of Their Interaction. European Journal Of Environmental And Civil Engineering, .
Abstract: Flexible Barriers Have Been Recently Proposed As A Promising Alternative For Trapping Woody Debris Driven By The Flow In Torrents And Rivers Before They Reach Elements At Risks. Small-Scale Experiments In Similitude With The Real-Scale Have Been Conducted In View Of Addressing The Interaction Between The Flow And The Barrier. A Particular Attention Was Paid To The Identification Of The Parameters With Influence On The Loading Experienced By The Barrier, Varying The Woody Debris Mixtures Characteristics, Water Discharge, Flume Inclination And Woody Debris Supply Mode. This Investigation Emphasised The Intricacy Of The Relation Between The Barrier Loading And The Characteristics Of The Trapped Logs And Of The Logs Accumulation. The Barrier Loading Revealed Inversely Proportional To The Woody Debris Accumulation Permittivity, Which Quantifies Its Capacity To Let The Water Seep Through. Permittivity Depended On The Way The Accumulation Built Up And On The Evolution Of Its Characteristics With Increasing Discharge And Trapped Logs Volume. Finally, The Loading Exerted By The Flow On The Barrier Was Derived From The Barrier Elongation, Revealing That It Could Be Modelled As A Hydrostatic Load With A Reduction Factor Of 0.5.
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Lamothe, A., Savarino, J., Ginot, P., Soussaintjean, L., Gautier, E., Akers, P., et al. (2023). An Extraction Method For Nitrogen Isotope Measurement Of Ammonium In Alow-Concentration Environment. Atmospheric Measurement Techniques, 161(171), 4015–4030.
Abstract: Ammonia (Nh3) Participates In The Nucleation And Growth Of Aerosols And Thus Plays A Major Role In Atmospheric Transparency, Pollution, Health, And Climate-Related Issues. Understanding Its Emission Sources Through Nitrogen Stable Isotopes Is Therefore A Major Focus Of Current Work To Mitigate The Adverse Effects Of Aerosol Formation. Since Ice Cores Can Preserve The Past Chemical Composition Of The Atmosphere For Centuries, They Are A Top Tool Of Choice For Understanding Past Nh3 Emissions Through Ammonium (Nh4+), The Form Of Nh3 Archived In Ice. However, The Remote Or High-Altitude Sites Where Glaciers And Ice Sheets Are Typically Localized Have Relatively Low Fluxes Of Atmospheric Nh4+ Deposition, Which Makes Ice Core Samples Very Sensitive To Laboratory Nh3 Contamination. As A Result, Accurate Techniques For Identifying And Tracking Nh3 Emissions Through Concentration And Isotopic Measurements Are Highly Sought To Constrain Uncertainties In Nh3 Emission Inventories And Atmospheric Reactivity Unknowns. Here, We Describe A Solid-Phase Extraction Method For Nh4+ Samples Of Low Concentration That Limits External Contamination And Produces Precise Isotopic Results. By Limiting Nh3Atm Exposure With A Scavenging Fume Hood And Concentrating The Targeted Nh4+ Through Ion Exchange Resin, We Successfully Achieve Isotopic Analysis Of 50 Nmol Nh4+ Samples With A 0.6 Parts Per Thousand Standard Deviation. This Extraction Method Is Applied To An Alpine Glacier Ice Core From Col Du Dome, Mont Blanc, Where We Successfully Demonstrate The Analytical Approach Through The Analysis Of Two Replicate 8 M Water Equivalent Ice Cores Representing 4 Years Of Accumulation With A Reproducibility Of +/- 2.1 Parts Per Thousand. Applying This Methodology To Other Ice Cores In Alpine And Polar Environments Will Open New Opportunities For Understanding Past Changes In Nh3 Emissions And Atmospheric Chemistry.
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Langue, C., Lavaysse, C., Vrac, M., & Flamant, C. (2023). Heat Wave Monitoring Over West African Cities: Uncertainties, Characterization And Recent Trends. Natural Hazards And Earth System Sciences, 232(4), 1313–1333.
Abstract: Heat Waves Can Be One Of The Most Dangerous Climatic Hazards Affecting The Planet, Having Dramatic Impacts On The Health Of Humans And Natural Ecosystems As Well As On Anthropogenic Activities, Infrastructures And Economy. Based On Climatic Conditions In West Africa, The Urban Centres Of The Region Appear To Be Vulnerable To Heat Waves. The Goals Of This Work Are Firstly To Assess The Potential Uncertainties Encountered In Heat Wave Detection And Secondly To Analyse Their Recent Trend In West Africa Cities During The Period 1993-2020. This Is Done Using Two State-Of-The-Art Reanalysis Products, Namely The Fifth-Generation European Centre For Medium-Range Weather Forecasts (Ecmwf) Reanalysis (Era5) And Modern-Era Retrospective Analysis For Research And Applications (Merra), As Well As Two Local Station Datasets, Namely Dakar-Yoff In Senegal And Aeroport Felix Houphouet-Boigny, Abidjan, In Cote D'Ivoire. An Estimate Of Station Data From Reanalyses Is Processed Using An Interpolation Technique: The Nearest Neighbour To The Station With A Land Sea Mask = 0.5. The Interpolated Temperatures From Local Stations In Dakar And Abidjan Show Slightly Better Correlation With Era5 Than With Merra. Three Types Of Uncertainty Are Discussed: The First Type Of Uncertainty Is Related To The Reanalyses Themselves, The Second Is Related To The Sensitivity Of Heat Wave Frequency And Duration To The Threshold Values Used To Monitor Them, And The Last One Is Linked To The Choice Of Indicators And The Methodology Used To Define Heat Waves. Three Sorts Of Heat Wave Have Been Analysed, Namely Those Occurring During Daytime, Nighttime, And Both Daytime And Nighttime Concomitantly. Four Indicators Have Been Used To Analyse Heat Waves Based On 2 M Temperature, Humidity, 10 M Wind Or A Combination Of These. We Found That Humidity Plays An Important Role In Nighttime Events; Concomitant Events Detected With Wet-Bulb Temperature Are More Frequent And Located Over The Northern Sahel. Strong And More Persistent Heat Waves Are Found In The Continental (Cont) Region. For All Indicators, We Identified 6 Years With A Significantly Higher Frequency Of Events (1998, 2005, 2010, 2016, 2019 And 2020), Possibly Due To Higher Sea Surface Temperatures In The Equatorial Atlantic Ocean Corresponding To El Nino Events For Some Years. A Significant Increase In The Frequency, Duration And Intensity Of Heat Waves In The Cities Has Been Observed During The Last Decade (2012-2020); This Is Thought To Be A Consequence Of Climate Change Acting On Extreme Events.
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Lapere, R., Thomas, J., Marelle, L., Ekman, A., Frey, M., Lund, M., et al. (2023). The Representation Of Sea Salt Aerosols And Their Role In Polar Climate Within Cmip6. Journal Of Geophysical Research-Atmospheres, 1281(6).
Abstract: Natural Aerosols And Their Interactions With Clouds Remain An Important Uncertainty Within Climate Models, Especially At The Poles. Here, We Study The Behavior Of Sea Salt Aerosols (Ssaer) In The Arctic And Antarctic Within 12 Climate Models From Cmip6. We Investigate The Driving Factors That Control Ssaer Abundances And Show Large Differences Based On The Choice Of The Source Function, And The Representation Of Aerosol Processes In The Atmosphere. Close To The Poles, The Cmip6 Models Do Not Match Observed Seasonal Cycles Of Surface Concentrations, Likely Due To The Absence Of Wintertime Ssaer Sources Such As Blowing Snow. Further Away From The Poles, Simulated Concentrations Have The Correct Seasonality, But Have A Positive Mean Bias Of Up To One Order Of Magnitude. Ssaer Optical Depth Is Derived From The Modis Data And Compared To Modeled Values, Revealing Good Agreement, Except For Winter Months. Better Agreement For Aerosol Optical Depth Than Surface Concentration May Indicate A Need For Improving The Vertical Distribution, The Size Distribution And/Or Hygroscopicity Of Modeled Polar Ssaer. Source Functions Used In Cmip6 Emit Very Different Numbers Of Small Ssaer, Potentially Exacerbating Cloud-Aerosol Interaction Uncertainties In These Remote Regions. For Future Climate Scenarios Ssp126 And Ssp585, We Show That Ssaer Concentrations Increase At Both Poles At The End Of The 21St Century, With More Than Two Times Mid-20Th Century Values In The Arctic. The Pre-Industrial Climate Cmip6 Experiments Suggest There Is A Large Uncertainty In The Polar Radiative Budget Due To Ssaer.Plain Language Summary Aerosols Emitted From The Ocean, Such As Sea Salt Particles (Aerosols), Are Critical For The Climate Of Polar Regions. However, There Is Still Uncertainty In Their Representation In Climate Models. The Purpose Of This Work Is To Evaluate The Representation Of Sea Salt Aerosols (Ssaer) In The Arctic And Antarctic In A Recent Model Inter-Comparison Initiative, And To Assess The Consequences For Our Understanding Of Present-Day And Future Polar Climate. We Find That The Models Disagree Between Them And With Observations From Ground Stations And From Space. This Suggests That The Formulation Of Sea Salt Emissions In Global Models Is Not Adapted For Polar Regions. With Sea Ice Retreat, Ssaer Will Most Likely Increase In The Future, Which Makes Addressing The Current Uncertainty An Important Next Step For The Scientific Community.
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Lapillonne, S., Fontaine, F., Liebault, F., Richefeu, V., & Piton, G. (2023). Debris-Flow Surges Of A Very Active Alpine Torrent: A Field Database. Natural Hazards And Earth System Sciences, 232(4), 1241–1256.
Abstract: This Paper Presents A Methodology To Analyse Debris Flows Focusing At The Surge Scale Rather Than The Full Scale Of The Debris-Flow Event, As Well As Its Application To A French Site. Providing Bulk Surge Features Like Volume, Peak Discharge, Front Height, Front Velocity And Froude Numbers Allows For Numerical And Experimental Debris-Flow Investigations To Be Designed With Narrower Physical Ranges And Thus For Deeper Scientific Questions To Be Explored. We Suggest A Method To Access Such Features At The Surge Scale That Can Be Applied To A Wide Variety Of Monitoring Stations. Requirements For Monitoring Stations For The Methodology To Be Applicable Include (I) Flow Height Measurements, (Ii) A Cross-Section Assumption And (Iii) A Velocity Estimation. Raw Data From Three Monitoring Stations On The Real Torrent (Drainage Area: 2 Km(2), Southeastern France) Are Used To Illustrate An Application To 34 Surges Measured From 2011 To 2020 At Three Monitoring Stations. Volumes Of Debris-Flow Surges On The Real Torrent Are Typically Sized At A Few Thousand Cubic Metres. The Peak Flow Height Of Surges Ranges From 1 To 2 M. The Peak Discharge Range Is Around A Few Dozen Cubic Metres Per Second. Finally, We Show That Froude Numbers Of Such Surges Are Near Critical.
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Lavorel, S., Anquetin, S., & Buclet, N. (2023). Trajectories Of Socio-Ecological Change In Mountains. Regional Environmental Change, .
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Law, R., Christoffersen, P., Mackie, E., Cook, S., Haseloff, M., & Gagliardini, O. (2023). Complex Motion Of Greenland Ice Sheet Outlet Glaciers With Basal Temperate Ice. Science Advances, 9(6).
Abstract: Uncertainty Associated With Ice Sheet Motion Plagues Sea Level Rise Predictions. Much Of This Uncertainty Arises From Imperfect Representations Of Physical Processes Including Basal Slip And Internal Ice Deformation, With Ice Sheet Models Largely Incapable Of Reproducing Borehole-Based Observations. Here, We Model Isolated Three-Dimensional Domains From Fast-Moving (Sermeq Kujalleq/Store Glacier) And Slow-Moving (Isunnguata Sermia) Ice Sheet Settings In Greenland. By Incorporating Realistic Geostatistically Simulated Topography, We Show That A Spatially Highly Variable Layer Of Temperate Ice (Much Softer Ice At The Pressure-Melting Point) Forms Naturally In Both Settings, Alongside Ice Motion Patterns Which Diverge Substantially From Those Obtained Using Smoothly Varying Bedmachine Topography. Temperate Ice Is Vertically Extensive (>100 Meters) In Deep Troughs But Thins Notably (<5 Meters) Over Bedrock Highs, With Basal Slip Rates Reaching >90 Or <5% Of Surface Velocity Dependent On Topography And Temperate Layer Thickness. Developing Parameterizations Of The Net Effect Of This Complex Motion Can Improve The Realism Of Predictive Ice Sheet Models.
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Le Cozannet, G., Nicholls, R., Durand, G., Slangen, A., Lincke, D., & Chapuis, A. (2023). Adaptation To Multi-Meter Sea-Level Rise Should Start Now. Environmental Research Letters, 181(9).
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Le Guillou, F., Gaultier, L., Ballarotta, M., Metref, S., Ubelmann, C., Cosme, E., et al. (2023). Regional Mapping Of Energetic Short Mesoscale Ocean Dynamics From Altimetry: Performances From Real Observations. Ocean Science, 191(5), 1517–1527.
Abstract: For Over 25 Years, Satellite Altimetry Has Provided Invaluable Information About The Ocean Dynamics At Many Scales. In Particular, Gridded Sea Surface Height (Ssh) Maps Allow Us To Estimate The Mesoscale Geostrophic Circulation In The Ocean. However, Conventional Interpolation Techniques Rely On Static Optimal Interpolation Schemes, Hence Limiting The Estimation Of Non-Linear Dynamics At Scales Not Well Sampled By Altimetry (I.E., Below 150-200Km At Mid-Latitudes). To Overcome This Limitation In The Resolution Of Small-Scale Ssh Structures (And Thus Small-Scale Geostrophic Currents), A Back-And-Forth Nudging Algorithm Combined With A Quasi-Geostrophic Model, A Technique Called Bfn-Qg, Has Been Successfully Applied On Simulated Ssh Data In Observing System Simulation Experiments (Osses). The Result Is A Significant Reduction In Interpolation Error And An Improvement In The Space-Time Resolutions Of The Experimental Gridded Product Compared To Those Of Operational Products. In This Study, We Propose That The Bfn-Qg Be Applied To Real Altimetric Ssh Data In A Highly Turbulent Region Spanning A Part Of The Agulhas Current. The Performances Are Evaluated Within Observing System Experiments (Oses) That Use Independent Data (Such As Independent Ssh, Sea Surface Temperature And Drifter Data) As Ground Truth. By Comparing The Mapping Performances To The Ones Obtained With Operational Products, We Show That The Bfn-Qg Improves The Mapping Of Short, Energetic Mesoscale Structures And Associated Geostrophic Currents Both In Space And Time. In Particular, The Bfn-Qg Improves (I) The Spatial Effective Resolution Of The Ssh Maps By A Factor Of 20%, (Ii) The Zonal And (Especially) The Meridional Geostrophic Currents, And (Iii) The Prediction Of Lagrangian Transport For Lead Times Up To 10D. Unlike The Results Obtained In The Osses, The Oses Reveal More Contrasting Performances In Low-Variability Regions, Which Are Discussed In The Paper.
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Le Roux, E., Evin, G., Samacoïts, R., Eckert, N., Blanchet, J., & Morin, S. (2023). Projection Of Snowfall Extremes In The French Alps As A Function Of Elevation And Global Warming Level. Cryosphere, 171(111), 4691–4704.
Abstract: Following The Projected Increase In Extreme Precipitation, An Increase In Extreme Snowfall May Be Expected In Cold Regions, E.G., For High Latitudes Or At High Elevations. By Contrast, In Low- To Medium-Elevation Areas, The Probability Of Experiencing Rainfall Instead Of Snowfall Is Generally Projected To Increase Due To Warming Conditions. Yet, In Mountainous Areas, Despite The Likely Existence Of These Contrasted Trends According To Elevation, Changes In Extreme Snowfall With Warming Remain Poorly Quantified. This Paper Assesses Projected Changes In Heavy And Extreme Snowfall, I.E., In Mean Annual Maxima And 100-Year Return Levels, In The French Alps As A Function Of Elevation And Global Warming Level. We Apply A Recent Methodology, Based On The Analysis Of Annual Maxima With Non-Stationary Extreme Value Models, To An Ensemble Of 20 Adjusted General Circulation Model-Regional Climate Model (Gcm-Rcm) Pairs From The Euro-Cordex Experiment Under The Representative Concentration Pathway 8.5 (Rcp8.5) Scenario. For Each Of The 23 Massifs Of The French Alps, Maxima In The Hydrological Sense (1 August To 31 July) Are Provided From 1951 To 2100 And Every 300 M Of Elevations Between 900 And 3600 M. Results Rely On Relative Or Absolute Changes Computed With Respect To Current Climate Conditions (Corresponding Here To + 1 Circle C Global Warming Level) At The Massif Scale And Averaged Over All Massifs. Overall, Daily Mean Annual Maxima Of Snowfall Are Projected To Decrease Below 3000 M And Increase Above 3600 M, While 100-Year Return Levels Are Projected To Decrease Below 2400 M And Increase Above 3300 M. At Elevations In Between, Values Are On Average Projected To Increase Until + 3 Circle C Of Global Warming And Then Decrease. At + 4 Circle C, Average Relative Changes In Mean Annual Maxima And 100-Year Return Levels, Respectively, Vary From – 26 % And – 15 % At 900 M To + 3 % And + 8 % At 3600 M. Finally, For Each Global Warming Level Between + 1.5 And + 4 Circle C, We Compute The Elevation Threshold That Separates Contrasted Trends, I.E., Where The Average Relative Change Equals Zero. This Elevation Threshold Is Shown To Be Lower For Higher Return Periods, And It Is Projected To Rise From 3000 M At + 1.5 Circle C To 3350 M At + 4 Circle C For Mean Annual Maxima And From 2600 To 3000 M For 100-Year Return Levels. These Results Have Implications For The Management Of Risks Related To Extreme Snowfall.
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Le, H., Nguyen, T., Gratiot, N., Deleersnijder, E., & Soares-Frazao, S. (2023). The Multi-Channel System Of The Vietnamese Mekong Delta: Impacts On The Flow Dynamics Under Relative Sea-Level Rise Scenarios. Water, 151(202).
Abstract: The Mekong Delta Has The World'S Third-Largest Surface Area. It Plays An Indisputable Role In The Economy And Livelihoods Of Vietnam And Cambodia, With Repercussions At Regional And Global Scales. During Recent Decades, The Vietnamese Part Of The Mekong Delta Underwent Profound Human Interventions (Construction Of Dykes And Multi-Channel Networks), Which Modified The Hydrodynamic Regime, Especially Cycles Of Field Submersion. In This Study, We First Applied A Full 2D Numerical Hydraulic Model, Telemac-2D, To Examine The Effects Of The Complex Channel And River Networks On The Spatial And Temporal Distribution Of The Flow In The 40,000 Km2 Of The Vietnamese Mekong Delta. Then, Two Scenarios Of Relative Sea-Level Rise In 2050 And 2100 Were Implemented To Simulate The Future Patterns Of Water Fluxes In The Delta. The Results Show That Dykes And Multi-Channel Networks Would Reduce The Inundation Area By 36% And Lessen The Peak Water Level By 15% And The Discharge Over The Floodplains By 24%. Despite This Protection, Under A Relative Sea-Level Rise Of 30 Cm And 100 Cm, The Maximum Flooded Area Could Occupy About 69% And 85% Of The Whole Delta In 2050 And 2100, Respectively.
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Lebon, Y., Francois, C., Navel, S., Vallier, F., Guillard, L., Pinasseau, L., et al. (2023). Aquifer Recharge By Stormwater Infiltration Basins: Hydrological And Vadose Zone Characteristics Control The Impacts Of Basins On Groundwater Chemistry And Microbiology. Science Of The Total Environment, 8658.
Abstract: Stormwater Infiltration Systems (Sis) Are Designed To Collect And Infiltrate Urban Stormwater Runoff Into The Ground For Flood Risk Mitigation And Artificial Aquifer Recharge. Many Studies Have Demonstrated That Infiltration Practices Can Im-Pact Groundwater Chemistry And Microbiology. However, Quantitative Assessments Of The Hydrogeological Factors Re-Sponsible Of These Changes Remain Scarce. Thus, The Present Study Aimed To Quantitatively Test Whether Changes Of Groundwater Chemistry And Microbiology Induced By Sis Were Linked To Two Factors Associated With Vadose Zone Prop-Erties (Vadose Zone Thickness, Water Transit Time From Surface To Groundwater) And One Factor Associated With Ground-Water Recharge Rate (Assessed By Groundwater Table Elevation During Rain Events). To Evaluate Changes In Chemistry (No3-, Po43- And Dissolved Organic Carbon Concentrations), Groundwater Samples Were Collected In Wells Located In Sis-Impacted And Non-Sis-Impacted Zones During Experimental Periods Of 10 Days. During The Same Periods, Clay Beads Were Incubated In The Same Wells To Measure Changes Of Groundwater Microbial Biofilms (Microbial Biomass, Dehydrogenase And Hydrolytic Activities) Induced By Sis. Results Showed That Changes In Po43- Supplied To Groundwa-Ter During Stormwater Infiltration Was Negatively Correlated With Vadose Zone Thickness. A Short Water Transit Time From Surface To Groundwater Increased Dissolved Organic Carbon Concentrations In The Aquifer Which, In Turn, Increased Biofilm Biomasses In Groundwater. The Groundwater Recharge Rate During Rain Events (Assessed By Groundwater Table Elevation) Diluted No3- Concentrations In The Aquifer But Also Influenced The Changes Of Biofilm Activities Induced By Sis. Groundwater Recharge Rate During Rain Events Probably Increased The Fluxes Of Water And Dissolved Organic Carbon In Groundwater, Stimulating The Activity Of Microbial Biofilms. Overall, The Present Study Is The First To Quantify Con-Jointly Several Factors And Processes (Water Transfer, Dilution, Solute Fluxes) That Could Explain The Impact Of Stormwater Infiltration On Chemistry And/Or Microbiology In Groundwater.
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Lecavalier, B., Tarasov, L., Balco, G., Spector, P., Hillenbrand, C., Buizert, C., et al. (2023). Antarctic Ice Sheet Paleo-Constraint Database. Earth System Science Data, 151(8), 3573–3596.
Abstract: We Present A Database Of Observational Constraints On Past Antarctic Ice Sheet Changes During The Last Glacial Cycle Intended To Consolidate The Observations That Represent Our Understanding Of Past Antarctic Changes And For State-Space Estimation And Paleo-Model Calibrations. The Database Is A Major Expansion Of The Initial Work Of Briggs And Tarasov (2013). It Includes New Data Types And Multi-Tier Data Quality Assessment. The Updated Constraint Database, Antice2 (Https://Theghub.Org/Resources/4884, Lecavalier Et Al., 2022), Consists Of Observations Of Past Grounded- And Floating-Ice-Sheet Extent, Past Ice Thickness, Past Relative Sea Level, Borehole Temperature Profiles, And Present-Day Bedrock Displacement Rates. In Addition To Paleo-Observations, The Present-Day Ice Sheet Geometry And Surface Ice Velocities Are Incorporated To Constrain The Present-Day Ice Sheet Configuration. The Method By Which The Data Are Curated Using Explicitly Defined Criteria Is Detailed. Moreover, The Observational Uncertainties Are Specified. The Methodology By Which The Constraint Database Can Be Applied To Evaluate A Given Ice Sheet Reconstruction Is Discussed. The Implementation Of The Antice2 Database For Antarctic Ice Sheet Model Calibrations Will Improve Antarctic Ice Sheet Predictions During Past Warm And Cold Periods And Yield More Robust Paleo-Model Spin Ups For Forecasting Future Ice Sheet Changes.
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Legrain, E., Blard, P., Kageyama, M., Charreau, J., Leduc, G., Bourdin, S., et al. (2023). Moisture Amplification Of The High-Altitude Deglacial Warming. Quaternary Science Reviews, 3183.
Abstract: In Response To Anthropogenic Warming, Glaciers Are Shrinking Almost Everywhere, Endangering Water Accessibility In Areas Located Downstream. Glacier Fluctuations Are At First Order Controlled By Local Precipitation And Temperature, But Large Uncertainties Persist On The Potential Role Of Local Moisture In Amplifying Or Dampening Temperature Changes At High-Elevation. Here, We Combine Glacier Extents And Sea Surface Temperature (Sst) During The Last Glacial Maximum (Lgm) To Quantify Altitudinal Thermal Gradients (Lapse Rate) From 40N To 40S Along The American Cordillera. We Also Constrain Modern Lapse Rates Based On Present Day Temperature And Sst Database To Explore How The Lapse Rate Has Changed Since The Lgm Along This North South Transect. Based On Proxy-Based Quantitative Paleo-Precipitation Estimations Above 2000 M, We Investigate How These Lapse Rate Changes Compare With Moisture Modifications Around The Cordillera And Discuss The Mechanisms That Potentially Controlled Lapse Rate Changes During The Post-Lgm Deglacial Warming. We Find That Lapse Rate Changes Are Linearly Related To Changes In Precipitation And Derive A Quantitative Relationship Between These Two Parameters. To Further Explore The Processes Involved In Controlling Lapse Rate Variations, We Use The Ipsl Global Climate Model Outputs, For The Lgm And Pre-Industrial States In This Region. The Ipsl Model Also Yields A Shallower Modern Lapse Rate In The Wetter Tropical Region, Confirming The Observed Correlation Between Precipitation Changes And Lapse Rate Variations. The Ipsl Model Also Supports A Close Coupling Of Continental Relative Moisture And Mean Annual Precipitation In The Studied Area, Indicating That Moisture Is Involved In The Precipitation – Lapse Rate Relationship. Our Results Suggest That Future Warming May Be Enhanced In High Altitude Regions Where Precipitation Is Expected To Increase. Using Our Most Reliable Relationship Linking Precipitation And Lapse Rate Changes, We Conclude That, Assuming A 1 C-Degrees Warming At Sea Level, A Mean Annual Precipitation Increases Of 500 Mm.A(-1) Could Lead To A Warming Amplification Of 4.1 +/- 0.8 C At 4000 M Asl (Mean Elevation Of Modern Glaciers). In This Case, A 2 C-Degrees Warming At Sea Level Would Yield >6 C Degrees Warming At 4000 M Asl. This Study Therefore Confirms That Special Attention Should Be Given To The Climate Projections Of Glacier Melting In Tropical And Mid Latitude Regions.
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Legrain, E., Parrenin, F., & Capron, E. (2023). A Gradual Change Is More Likely To Have Caused The Mid-Pleistocene Transition Than An Abrupt Event. Communications Earth & Environment, .
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Legrand, M., Mcconnell, J., Bergametti, G., Plach, A., Desboeufs, K., Chellman, N., et al. (2023). A Two-Fold Increase Of Phosphorus In Alpine Ice Over The Twentieth Century: Contributions From Dust, Primary Biogenic Emissions, Coal Burning, And Pig Iron Production. Journal Of Geophysical Research-Atmospheres, 1281(191).
Abstract: Phosphorus (P) Is A Key Nutrient For Many Organisms But Its Global Atmospheric Budget Is Largely Unconstrained. Estimates Of Major Emissions Sources Such As Fossil-Fuel Combustion Range From Similar To 0.02 To 1.1 Tg Yr-1, And Primary Biogenic Emissions Range From 0.16 To 1.0 Tg Yr-1. Here We Used Detailed Measurements Of Phosphorus In Alpine Ice Cores Extracted From The Col Du Dome (Cdd) Glacier Located Near The Mont Blanc Summit And Atmospheric Model Simulations To Evaluate Changes In Western European Emissions From Pre-Industrial (Pi) To Modern Times. The Ice-Core Records Show That P Concentrations During The Pi Were About 0.9 Ng G-1, Of Which One Third Was Of Crustal Origin And Two Thirds The Result Of Primary Biogenic Emissions. Concentrations Were Higher Throughout The 20Th Century, Reaching 2.5 Ng G-1 In The 1980S. Analysis Of Source Tracers Measured In The Same Ice, Commodity Productions Statistics, And Other Information Suggest That The Increase In P Throughout The 20Th Century Was Caused By Enhanced Emissions From Natural And Anthropogenic Sources. Coal Burning And Steel Industry Represented The Main Anthropogenic Sources During The First And Second Half Of The Century, Respectively. After 1950, The Increase In P Was Also Caused By Enhanced Dust Emissions, With Increased Biogenic Emissions Caused By Recent Changes Of Use-Land Also Contributing. These Findings Provide Important Constraints On The Atmospheric P Budget At The Scale Of Western Europe During The Recent Centuries. Phosphorus Is An Important Nutrient For Terrestrial And Aquatic Flora And Fauna. Whereas Dust Aerosol Emissions Are The Dominant Atmospheric Source Of Phosphorus On A Global Scale, Other Sources Such As Biogenic Particles Emitted By Vegetation, As Well As Fossil-Fuel Combustion, May Represent Important Sources In Less-Dusty Industrialized Regions. Estimates Of These Non-Crustal Sources Are Uncertain, However, With Values Often Varying By An Order Of Magnitude Or More. Comparison With Long-Term Pollution Records Extracted From Well-Dated Ice Cores Provides A Means Of Evaluating These Estimates. Here, We Analyzed Phosphorus In Ice Cores Extracted Near The Mont Blanc Summit In The French Alps To Develop An 1850 To 2000 Record. Phosphorus Deposition Doubled During This Period, With Increases Attributed To Enhancement Of Both Natural (Dust And Biogenic Particles Emitted By Vegetation) And Anthropogenic (Mainly Coal Burning And The Steel Industry) Emissions. A Doubling Of Phosphorus In Alpine Ice Deposited Between 1850 And 2000 From Increasing Natural And Anthropogenic Emissionsphosphorus Deposition Trends From 1900 To 1975 Mainly Attributed To Coal Burning And Pig Iron Industry Emissionsnatural European Phosphorus Sources Dominated By Primary Emissions Of Biogenic (70%) And Dust (30%) Particles That Were Enhanced After 1975
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Legrand, M., Mcconnell, J., Bergametti, G., Plach, A., Desboeufs, K., Chellman, N., et al. (2023). A Two-Fold Increase Of Phosphorus In Alpine Ice Over The Twentieth Century: Contributions From Dust, Primary Biogenic Emissions, Coal Burning, And Pig Iron Production. Journal Of Geophysical Research-Atmospheres, 1281(191).
Abstract: Phosphorus (P) Is A Key Nutrient For Many Organisms But Its Global Atmospheric Budget Is Largely Unconstrained. Estimates Of Major Emissions Sources Such As Fossil-Fuel Combustion Range From Similar To 0.02 To 1.1 Tg Yr(-1), And Primary Biogenic Emissions Range From 0.16 To 1.0 Tg Yr(-1). Here We Used Detailed Measurements Of Phosphorus In Alpine Ice Cores Extracted From The Col Du D & Ocirc;Me (Cdd) Glacier Located Near The Mont Blanc Summit And Atmospheric Model Simulations To Evaluate Changes In Western European Emissions From Pre-Industrial (Pi) To Modern Times. The Ice-Core Records Show That P Concentrations During The Pi Were About 0.9 Ng G(-1), Of Which One Third Was Of Crustal Origin And Two Thirds The Result Of Primary Biogenic Emissions. Concentrations Were Higher Throughout The 20Th Century, Reaching 2.5 Ng G(-1) In The 1980S. Analysis Of Source Tracers Measured In The Same Ice, Commodity Productions Statistics, And Other Information Suggest That The Increase In P Throughout The 20Th Century Was Caused By Enhanced Emissions From Natural And Anthropogenic Sources. Coal Burning And Steel Industry Represented The Main Anthropogenic Sources During The First And Second Half Of The Century, Respectively. After 1950, The Increase In P Was Also Caused By Enhanced Dust Emissions, With Increased Biogenic Emissions Caused By Recent Changes Of Use-Land Also Contributing. These Findings Provide Important Constraints On The Atmospheric P Budget At The Scale Of Western Europe During The Recent Centuries.
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Legrand, M., Mcconnell, J., Bergametti, G., Plach, A., Desboeufs, K., Chellman, N., et al. (2023). A Two-Fold Increase Of Phosphorus In Alpine Ice Over The Twentieth Century: Contributions From Dust, Primary Biogenic Emissions, Coal Burning, And Pig Iron Production. Journal Of Geophysical Research-Atmospheres, 1281(191).
Abstract: Phosphorus (P) Is A Key Nutrient For Many Organisms But Its Global Atmospheric Budget Is Largely Unconstrained. Estimates Of Major Emissions Sources Such As Fossil-Fuel Combustion Range From Similar To 0.02 To 1.1 Tg Yr(-1), And Primary Biogenic Emissions Range From 0.16 To 1.0 Tg Yr(-1). Here We Used Detailed Measurements Of Phosphorus In Alpine Ice Cores Extracted From The Col Du D & Ocirc;Me (Cdd) Glacier Located Near The Mont Blanc Summit And Atmospheric Model Simulations To Evaluate Changes In Western European Emissions From Pre-Industrial (Pi) To Modern Times. The Ice-Core Records Show That P Concentrations During The Pi Were About 0.9 Ng G(-1), Of Which One Third Was Of Crustal Origin And Two Thirds The Result Of Primary Biogenic Emissions. Concentrations Were Higher Throughout The 20Th Century, Reaching 2.5 Ng G(-1) In The 1980S. Analysis Of Source Tracers Measured In The Same Ice, Commodity Productions Statistics, And Other Information Suggest That The Increase In P Throughout The 20Th Century Was Caused By Enhanced Emissions From Natural And Anthropogenic Sources. Coal Burning And Steel Industry Represented The Main Anthropogenic Sources During The First And Second Half Of The Century, Respectively. After 1950, The Increase In P Was Also Caused By Enhanced Dust Emissions, With Increased Biogenic Emissions Caused By Recent Changes Of Use-Land Also Contributing. These Findings Provide Important Constraints On The Atmospheric P Budget At The Scale Of Western Europe During The Recent Centuries.
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Legrand, M., Mcconnell, J., Bergametti, G., Preunkert, S., Chellman, N., Desboeufs, K., et al. (2023). Alpine-Ice Record Of Bismuth Pollution Implies A Major Role Of Military Use During World War Ii. Scientific Reports, .
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Li, C., Enrico, M., Magand, O., Araujo, B., Le Roux, G., Osterwalder, S., et al. (2023). A Peat Core Hg Stable Isotope Reconstruction Of Holocene Atmospheric Hg Deposition At Amsterdam Island (37.8(O)S). Geochimica Et Cosmochimica Acta, 3413, 62–74.
Abstract: Mercury (Hg) Stable Isotopes Have Been Broadly Used To Investigate The Sources, Transformation And Deposition Of Atmospheric Hg During The Industrial Era Thanks To The Multiple Isotope Signatures Deriving From Mass-Dependent (Represented By Delta Hg-202) And Mass-Independent Fractionation (Represented By Axxxhg) In The Environment. Less Is Known About The Impact Of Past Climate Change On Atmospheric Hg Deposition And Cycling, And Whether Hg Isotopes Covary With Past Climate. Here, We Investigate Hg Concentration And Hg Isotope Signatures In A 6600-Year-Old Ombrotrophic Peat Record From Amsterdam Island (Ams, 37.8(O)S), And In Modern Ams Rainfall And Gaseous Elemental Hg (Hg-0) Samples. Results Show That Holocene Atmospheric Hg Deposition And Plant Hg Uptake Covary With Dust Deposition, And Are Both Lower Under A High Humidity Regime Associated With Enhanced Southern Westerly Winds. Modern Ams Gaseous Hg-0 And Rainfall Hgii Isotope Signatures Are Similar To Those In The Northern Hemisphere (Nh). Holocene Peat Delta Hg-199 And A200Hg Are Significantly Correlated (R2 = 0.67, P < 0.001, N = 58), Consistently Oscillating Between The Modern Hg-0 And Rainfall Hg-Ii End-Members. Peat A200Hg And Delta Hg-199 Provide Evidence Of Plant Uptake Of Hg-0 As The Dominant Pathway Of Hg Deposition To Ams Peatland, With Some Exceptions During Humid Periods. In Contrast To Nh Archives Generally Documenting A Modern Increase In Delta Hg-199, Recent Peat Layers (Post-1900Ce) From Ams Show The Lowest Delta Hg-199 In The Peat Profile (-0.42 +/- 0.27 Parts Per Thousand, 1Cs, N = 8). This Likely Reflects A Significant Change In The Post-Depositional Process On Deposited Anthropogenic Hg In 20Th Century (I.E. Dark Abiotic Reduction), Enabling More Negative Delta Hg-199 To Be Observed In Ams Peat. We Further Find That The Oscillations Of Hg Isotopes Are Consistent With Established Holocene Climate Variability From Dust Proxies. We Suggest Peat Hg Isotope Records Might Be A Valid Rainfall Indicator. (C) 2022 The Authors. Published By Elsevier Ltd.
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Li, L., Deremble, B., Lahaye, N., & Memin, E. (2023). Stochastic Data-Driven Parameterization Of Unresolved Eddy Effects In A Baroclinic Quasi-Geostrophic Model. Journal Of Advances In Modeling Earth Systems, 151(2).
Abstract: In This Work, A Stochastic Representation Based On A Physical Transport Principle Is Proposed To Account For Mesoscale Eddy Effects On The Large-Scale Oceanic Circulation. This Stochastic Framework Arises From A Decomposition Of The Lagrangian Velocity Into A Smooth-In-Time Component And A Highly Oscillating Noise Term. One Important Characteristic Of This Random Model, Without Any External Forcing And Damping, Is That It Conserves The Total Energy Of The Resolved Flow For Any Realization. The Proposed Stochastic Formulation Is Successfully Implemented In A Well Established Multi-Layered Quasi-Geostrophic Dynamical Core. The Empirical Spatial Correlation Of The Unresolved Noise Is Calibrated From The Eddy-Resolving Simulation Data. In Particular, A Stationary Correction Drift Can Be Introduced In The Noise Through Girsanov Transformation. This Non-Intuitive Term Appears To Be Important In Reproducing On A Coarse Mesh The Eastward Jet Of The Wind-Driven Double-Gyre Circulation. In Addition, A Projection Method Has Been Proposed To Constrain The Noise To Act Along The Iso-Surfaces Of The Vertical Stratification. The Resulting Noise Enables Us To Improve The Intrinsic Low-Frequency Variability Of The Large-Scale Current.
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Liebault, F., Piegay, H., Cassel, M., & Arnaud, F. (2023). Bedload Tracing With Rfid Tags In Gravel-Bed Rivers: Review And Meta-Analysis After 20?Years Of Field And Laboratory Experiments. Earth Surface Processes And Landforms, .
Abstract: Soon After Their First Deployment In Rivers In The Early 2000S, Rfid Tags Rapidly Became The Reference Technology For Bedload Tracing In Rivers. We Can Estimate From The Literature That During The Last 20 Years, More Than 30,000 Rfid Tracers Have Been Injected In Gravel-Bed Rivers All Around The World To Study Bedload Transport. Many Field Experiments Have Been Reported In A Great Diversity Of Fluvial Environments, Complemented By Many Laboratory Experiments And Methodological Developments. This Paper Proposes A Review Of These Works, Notably Based On The Compilation Of More Than 350 Rfid Surveys, Complemented By 97 Magnetic Surveys, For A Total Of 125 Study Sites. The Meta-Analysis Of This Database Shows That Rfid Tracers Have Improved Our Understanding Of Sediment Transport In Fluvial Environments With Rapid Bedload Dispersion. It Is Also Shown That Central Positions Of Tracer Plumes Are Moving Faster Over Time Than Tracer Leading Fronts, As Attested By A General Relation Between Maximum And Mean Distances Of Transport. The Most Recent Methodological Developments Based On The Use Of Active Uhf Rfid Tags Show That It Is Now Possible To Conduct Efficient Bedload Tracing Experiments Not Only In Small Streams, But Also In Large Gravel-Bed Rivers Or Very Active Braided Channels. Other Addressed Topics Include Rfid Deployment And Survey In River Channels, Controlling Factors Of Tracer Mobility (Flow Conditions, Grain-Size And Shape, Channel Morphology), Bedload Monitoring Approaches Using Rfid Tracers, And Applications Of Rfid Tracers For Evaluating Human Effects On Bedload Transport. Key Challenges Of Bedload Tracing With Rfid Tags Are Also Proposed. A Review Of Field And Laboratory Radio Frequency Identification (Rfid) Bedload Tracing Experiments Is Proposed, Including A Meta-Analysis Of Data Coming From 459 Tracer Surveys For A Total Of 125 Study Sites. Rfid Tracers Open New Avenues For Exploring Fluvial Environments Prone To Rapid Bedload Dispersion. The Most Recent Methodological Developments Based On Active Ultra-High Frequency Rfid Tags Show That It Is Now Possible To Conduct Efficient Bedload Tracing Experiments Not Only In Small Streams But Also In Large Gravel-Bed Rivers Or Active Braided Channels.Image
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Loffler, P., Escher, B., Baduel, C., Virta, M., & Lai, F. (2023). Antimicrobial Transformation Products In The Aquatic Environment: Global Occurrence, Ecotoxicological Risks, And Potential Of Antibiotic Resistance. Environmental Science & Technology, .
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Lott, F., Beljaars, A., Pauget, L., & Deremble, B. (2023). Neutral And Stratified Turbulent Boundary-Layer Flow Over Low Mountains. Quarterly Journal Of The Royal Meteorological Society, .
Abstract: A Theory For Flow Over Gentle Hills Using A Mixing-Length Turbulence Closure Is Developed To Describe The Transition From Turbulent Orographic Form Drag To Gravity Wave Drag. It Confirms That The First Is Associated With Downstream Sheltering, And The Second With Upstream Blocking And Strong Downslope Winds. It Shows That The Altitude At Which The Incident Flow Needs To Be Taken To Calculate The Drag Is The Inner Layer Scale At Which Dissipation Equilibrates Disturbance Advection. It Also Shows That The Parameter That Controls The Transition, Here A Richardson Number, Compares The Mountain Length With The Altitude Of The Turning Points Above Which The Upward-Propagating Gravity Waves Become Evanescent. Our Solutions Are Also Used To Show That The Downslope Winds Penetrate Well Into The Inner Layer And That A Good Fraction Of The Drag Is Deposited In The Inner Layer: All Of It In The Neutral Case, A Large Fraction In The Intermediate Cases When There Are Trapped Lee Waves, And Even In Stable Situations Without Trapping Part Of The Gravity Wave Drag Is Eroded In The Inner Layer. Some Discussion On How To Combine Neutral And Stratified Effects In The Parametrization Of Subgrid Scale Orography In Large-Scale Models Is Given. A Theory For The Interaction Between A Boundary Layer And A Low Mountain Is Derived. The Incident Wind Considered (U0$$ {U}_0 $$, Left Panel) Presents A Logarithmic Profile Near The Surface. The Theory Describes The Transition From Neutral To Stratified Flows, And The Systems Of Mountain Waves (Upward Propagating And Trapped, See Right Panel) That Develop During The Transition. The Theory Also Reproduces The Transition From Downstream Sheltering To Downslope Winds (Zoom) As Stratification Increases. The Mountain Drag And Reynolds Stress Profiles Are Also Discussed.Image
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Maclennan, M., Lenaerts, J., Shields, C., Hoffman, A., Wever, N., Thompson-Munson, M., et al. (2023). Climatology And Surface Impacts Of Atmospheric Rivers On West Antarctica. Cryosphere, 171(2), 865–881.
Abstract: Atmospheric Rivers (Ars) Transport Large Amounts Of Moisture From The Mid- To High-Latitudes And They Are A Primary Driver Of The Most Extreme Snowfall Events, Along With Surface Melting, In Antarctica. In This Study, We Characterize The Climatology And Surface Impacts Of Ars On West Antarctica, Focusing On The Amundsen Sea Embayment And Marie Byrd Land. First, We Develop A Climatology Of Ars In This Region, Using An Antarctic-Specific Ar Detection Tool Combined With The Modern-Era Retrospective Analysis For Research And Applications, Version 2 (Merra-2) And The European Centre For Medium-Range Weather Forecasts (Ecmwf) Reanalysis V5 (Era5) Atmospheric Reanalyses. We Find That While Ars Are Infrequent (Occurring 3 % Of The Time), They Cause Intense Precipitation In Short Periods Of Time And Account For 11 % Of The Annual Surface Accumulation. They Are Driven By The Coupling Of A Blocking High Over The Antarctic Peninsula With A Low-Pressure System Known As The Amundsen Sea Low. Next, We Use Observations From Automatic Weather Stations On Thwaites Eastern Ice Shelf With The Firn Model Snowpack And Interferometric Reflectometry (Ir) To Examine A Case Study Of Three Ars That Made Landfall In Rapid Succession From 2 To 8 February 2020, Known As An Ar Family Event. While Accumulation Dominates The Surface Impacts Of The Event On Thwaites Eastern Ice Shelf (> 100 Kgm(-2) Or Millimeters Water Equivalent), We Find Small Amounts Of Surface Melt As Well (< 5 Kgm(-2)). The Results Presented Here Enable Us To Quantify The Past Impacts Of Ars On West Antarctica'S Surface Mass Balance (Smb) And Characterize Their Interannual Variability And Trends, Enabling A Better Assessment Of Future Ar-Driven Changes In The Smb.
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Magand, O., Angot, H., Bertrand, Y., Sonke, J., Laffont, L., Duperray, S., et al. (2023). Over A Decade Of Atmospheric Mercury Monitoring At Amsterdam Island In The French Southern And Antarctic Lands. Scientific Data, 101(1).
Abstract: The Minamata Convention, A Global And Legally Binding Treaty That Entered Into Force In 2017, Aims To Protect Human Health And The Environment From Harmful Mercury (Hg) Effects By Reducing Anthropogenic Hg Emissions And Environmental Levels. The Conference Of The Parties Is To Periodically Evaluate The Convention'S Effectiveness, Starting In 2023, Using Existing Monitoring Data And Observed Trends. Monitoring Atmospheric Hg Levels Has Been Proposed As A Key Indicator. However, Data Gaps Exist, Especially In The Southern Hemisphere. Here, We Present Over A Decade Of Atmospheric Hg Monitoring Data At Amsterdam Island (37.80 Degrees S, 77.55 Degrees E), In The Remote Southern Indian Ocean. Datasets Include Gaseous Elemental And Oxidised Hg Species Ambient Air Concentrations From Either Active/Continuous Or Passive/Discrete Acquisition Methods, And Annual Total Hg Wet Deposition Fluxes. These Datasets Are Made Available To The Community To Support Policy-Making And Further Scientific Advancements.
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Mahaman, R., Nazoumou, Y., Favreau, G., Ousmane, B., Boucher, M., Babaye, M., et al. (2023). Paleochannel Groundwater Discharge To The River Niger In The Iullemmeden Basin Estimated By Near- Surface Geophysics And Piezometry. Environmental Earth Sciences, .
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Maier, N., Andersen, J., Mouginot, J., Gimbert, F., & Gagliardini, O. (2023). Wintertime Supraglacial Lake Drainage Cascade Triggers Large-Scale Ice Flow Response In Greenland. Geophysical Research Letters, 505(4).
Abstract: Surface Melt Forces Summertime Ice-Flow Accelerations On Glaciers And Ice Sheets. Here, We Show That Large Meltwater-Forced Accelerations Also Occur During Wintertime In Greenland. We Document Supraglacial Lakes (Sgls) Draining In Cascades At Unusually High Elevation, Causing An Expansive Flow Acceleration Over A Similar To 5,200 Km(2) Region During Winter. The Three-Component Interferometric Surface Velocity Field And Decomposition Modeling Reveal The Underlying Flood Propagation With Unprecedented Detail As It Traveled Over 160 Km From The Drainage Site To The Margin, Providing Novel Constraints On Subglacial Water Pathways, Drainage Morphology, And Links With Basal Sliding. The Triggering Sgls Continuously Grew Over 40 Years And Suddenly Released Decades Of Stored Meltwater, Demonstrating Surface Melting Can Impact Dynamics Well Beyond Melt Production. We Show These Events Are Likely Common And Thus Their Cumulative Impact On Dynamics Should Be Further Evaluated.
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Mallet, M., Humphries, R., Fiddes, S., Alexander, S., Altieri, K., Angot, H., et al. (2023). Untangling The Influence Of Antarctic And Southern Ocean Life On Clouds. Elementa-Science Of The Anthropocene, 111(1).
Abstract: Polar Environments Are Among The Fastest Changing Regions On The Planet. It Is A Crucial Time To Make Significant Improvements In Our Understanding Of How Ocean And Ice Biogeochemical Processes Are Linked With The Atmosphere. This Is Especially True Over Antarctica And The Southern Ocean Where Observations Are Severely Limited And The Environment Is Far From Anthropogenic Influences. In This Commentary, We Outline Major Gaps In Our Knowledge, Emerging Research Priorities, And Upcoming Opportunities And Needs. We Then Give An Overview Of The Large-Scale Measurement Campaigns Planned Across Antarctica And The Southern Ocean In The Next 5 Years That Will Address The Key Issues. Until We Do This, Climate Models Will Likely Continue To Exhibit Biases In The Simulated Energy Balance Over This Delicate Region. Addressing These Issues Will Require An International And Interdisciplinary Approach Which We Hope To Foster And Facilitate With Ongoing Community Activities And Collaborations.
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Maloku, K., Hingray, B., & Evin, G. (2023). Accounting For Precipitation Asymmetry In A Multiplicative Random Cascade Disaggregation Model. Hydrology And Earth System Sciences, 272(202), 3643–3661.
Abstract: Analytical Multiplicative Random Cascades (Mrcs) Are Widely Used For The Temporal Disaggregation Of Coarse-Resolution Precipitation Time Series. This Class Of Models Applies Scaling Models To Represent The Dependence Of The Cascade Generator On The Temporal Scale And The Precipitation Intensity. Although Determinant, The Dependence On The External Precipitation Pattern Is Usually Disregarded In The Analytical Scaling Models. Our Work Presents A Unified Mrc Modelling Framework That Allows The Cascade Generator To Depend In A Continuous Way On The Temporal Scale, Precipitation Intensity And A So-Called Precipitation Asymmetry Index.Different Mrc Configurations Are Compared For 81 Locations In Switzerland With Contrasted Climates. The Added Value Of The Dependence Of The Mrc On The Temporal Scale Appears To Be Unclear, Unlike What Was Suggested In Previous Works. Introducing The Precipitation Asymmetry Dependence Into The Model Leads To A Drastic Improvement In Model Performance For All Statistics Related To Precipitation Temporal Persistence (Wet-Dry Transition Probabilities, Lag-N Autocorrelation Coefficients, Lengths Of Dry-Wet Spells). Accounting For Precipitation Asymmetry Seems To Solve This Important Limitation Of Previous Mrcs.The Model Configuration That Only Accounts For The Dependence On Precipitation Intensity And Asymmetry Is Highly Parsimonious, With Only Five Parameters, And Provides Adequate Performances For All Locations, Seasons And Temporal Resolutions. The Spatial Coherency Of The Parameter Estimates Indicates A Real Potential For Regionalisation And For Further Application To Any Location In Switzerland.
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Mardoñez, V., Pandolfi, M., Borlaza, L., Jaffrezo, J., Alastuey, A., Besombes, J., et al. (2023). Source Apportionment Study On Particulate Air Pollution In Two High-Altitude Bolivian Cities: La Paz And El Alto. Atmospheric Chemistry And Physics, 232(181), 10325–10347.
Abstract: La Paz And El Alto Are Two Fast-Growing, High-Altitude Bolivian Cities Forming The Second-Largest Metropolitan Area In The Country. Located Between 3200 And 4050 M A.S.L. (Above Sea Level), These Cities Are Home To A Burgeoning Population Of Approximately 1.8 Million Residents. The Air Quality In This Conurbation Is Heavily Influenced By Urbanization; However, There Are No Comprehensive Studies Evaluating The Sources Of Air Pollution And Their Health Impacts. Despite Their Proximity, The Substantial Variation In Altitude, Topography, And Socioeconomic Activities Between La Paz And El Alto Result In Distinct Sources, Dynamics, And Transport Of Particulate Matter (Pm). In This Investigation, Pm10 Samples Were Collected At Two Urban Background Stations Located In La Paz And El Alto Between April 2016 And June 2017. The Samples Were Later Analyzed For A Wide Range Of Chemical Species Including Numerous Source Tracers (Oc, Ec, Water-Soluble Ions, Sugar Anhydrides, Sugar Alcohols, Trace Metals, And Molecular Organic Species). The United States Environmental Protection Agency (U.S. Epa) Positive Matrix Factorization (Pmf V.5.0) Receptor Model Was Employed For The Source Apportionment Of Pm10. This Is One Of The First Source Apportionment Studies In South America That Incorporates An Extensive Suite Of Organic Markers, Including Levoglucosan, Polycyclic Aromatic Hydrocarbons (Pahs), Hopanes, And Alkanes, Alongside Inorganic Species. The Multisite Pmf Resolved 11 Main Sources Of Pm. The Largest Annual Contribution To Pm10 Came From The Following Two Major Sources: The Ensemble Of The Four Vehicular Emissions Sources (Exhaust And Non-Exhaust), Accountable For 35 % And 25 % Of The Measured Pm In La Paz And El Alto, Respectively; And Dust, Which Contributed 20 % And 32 % To The Total Pm Mass. Secondary Aerosols Accounted For 22 % (24 %) In La Paz (El Alto). Agricultural Smoke Resulting From Biomass Burning In The Bolivian Lowlands And Neighboring Countries Contributed To 9 % (8 %) Of The Total Pm10 Mass Annually, Increasing To 17 % (13 %) Between August-October. Primary Biogenic Emissions Were Responsible For 13 % (7 %) Of The Measured Pm10 Mass. Additionally, A Profile Associated With Open Waste Burning Occurring From May To August Was Identified. Although This Source Contributed Only To 2 % (5 %) Of The Total Pm10 Mass, It Constitutes The Second Largest Source Of Pahs, Which Are Compounds Potentially Hazardous To Human Health. Our Analysis Additionally Resolved Two Different Traffic-Related Factors, A Lubricant Source (Not Frequently Identified), And A Non-Exhaust Emissions Source. Overall, This Study Demonstrates That Pm10 Concentrations In La Paz And El Alto Region Are Predominantly Influenced By A Limited Number Of Local Sources. In Conclusion, To Improve Air Quality In Both Cities, Efforts Should Primarily Focus On Addressing Dust, Traffic Emissions, Open Waste Burning, And Biomass Burning.
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Marengo, J., Espinoza, J., Bettolli, L., Cunha, A., Molina-Carpio, J., Skansi, M., et al. (2023). A Cold Wave Of Winter 2021 In Central South America: Characteristics And Impacts. Climate Dynamics, .
Abstract: During The Austral Winter (June-August) Of 2021, The Meteorological Services Of Brazil, Argentina, Peru, Paraguay, Bolivia, And Chile All Issued Forecasts For Unusually Cold Conditions. Record-Low Minimum Temperatures And Cold Spells Were Documented, Including One Strong Cold Wave Episode That Affected 5 Countries. In This Study, We Define A Cold Wave As A Period In Which Daily Maximum And Minimum Air Temperatures Are Below The Corresponding Climatological 10Th Percentile For Three Or More Consecutive Days. The Intense Cold Wave Event In The Last Week Of June, 2021, Resulted In Record-Breaking Minimum Daily Temperatures In Several Places In Central South America And Chile. Several Locations Had Temperatures About 10 Degrees C Below Average, Central South America Had Freezing Conditions, And Southern Brazil Even Saw Snow. The Cold Air Surge Was Characterized By An Intense Upper-Air Trough Located Close To 35 Degrees S And 70 Degrees W. The Southerly Flow To The West Of This Trough Brought Very Cold Air Northward Into Subtropical And Tropical South America. A Northward Flow Between The Lower-Level Cyclonic And Anticyclonic Perturbations Caused The Intense Southerly Flow Between The Upper-Level Ridge And Trough. This Condition Facilitated The Inflow Of Near-Surface Cold Air From Southern Argentina Into Southeastern Brazil And Tropical South America East Of The Andes. In The City Of Sao Paulo, The Cold Wave Caused The Death Of 13 Homeless People From Hypothermia. Frost And Snow Across Southern And Southeastern Brazil Caused Significant Damage To Coffee, Sugarcane, Oranges, Grapes, And Other Fruit And Vegetable Crops. Wine And Coffee Production Fell, The Latter By 30%, And Prices Of Food And Commodities In The Region Rose.
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Marsal, A., Slama, R., Lyon-Caen, S., Borlaza, L., Jaffrezo, J., Boudier, A., et al. (2023). Prenatal Exposure To Pm2.5 Oxidative Potential And Lung Function In Infants And Preschool- Age Children: A Prospective Study. Environmental Health Perspectives, 1311(1).
Abstract: Background: Fine Particulate Matter (Pm2.5) Has Been Found To Be Detrimental To Respiratory Health Of Children, But Few Studies Have Examined The Effects Of Prenatal Pm2.5 Oxidative Potential (Op) On Lung Function In Infants And Preschool Children.Objectives: We Estimated The Associations Of Personal Exposure To Pm2.5 And Op During Pregnancy On Offspring Objective Lung Function Parameters And Compared The Strengths Of Associations Between Both Exposure Metrics.Methods: We Used Data From 356 Mother-Child Pairs From The Sepages Cohort. Pm Filters Collected Twice During A Week Were Analyzed For Op, Using The Dithiothreitol (Dtt) And The Ascorbic Acid (Aa) Assays, Quantifying The Exposure Of Each Pregnant Woman. Lung Function Was Assessed With Tidal Breathing Analysis (Tbfvl) And Nitrogen Multiple-Breath Washout (N2Mbw) Test, Performed At 6 Wk, And Airwave Oscillometry (Aos) Performed At 3 Y. Associations Of Prenatal Pm2.5 Mass And Op With Lung Function Parameters Were Estimated Using Multiple Linear Regressions.Results: In Neonates, An Interquartile (Iqr) Increase In Opdttv (0.89 Nmol/Min/M3) Was Associated With A Decrease In Functional Residual Capacity (Frc) Measured Byn2Mbw [Beta = – 2.26 Ml; 95% Confidence Interval (Ci): -4.68, 0.15]. Associations With Pm2.5 Showed Similar Patterns In Comparison With Opdtt V But Of Smaller Magnitude. Lung Clearance Index (Lci) And Tbfvl Parameters Did Not Show Any Clear Association With The Exposures Considered. At 3 Y, Increased Frequency-Dependent Resistance Of The Lungs (Rrs7-19) From Aos Tended To Be Associated With Higher Opdtt V (Beta = 0.09 Hpa X S/L; 95% Ci: -0.06, 0.24) And Opaav (Iqr =1.14 Nmol/Min/M3; Beta = 0.12 Hpa X S/L; 95% Ci: -0.04, 0.27) But Not With Pm2.5 (Iqr = 6.9 Mu G/M3; Beta = 0.02 Hpa X S/L; 95% Ci: -0.13, 0.16). Results For Frc And Rrs7-19 Remained Similar In Op Models Adjusted On Pm2.5.Discussion: Prenatal Exposure To Opdtt V Was Associated With Several Offspring Lung Function Parameters Over Time, All Related To Lung Volumes. Https://Doi.Org/10.1289/Ehp11155
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Martin, L., Westermann, S., Magni, M., Brun, F., Fiddes, J., Lei, Y., et al. (2023). Recent Ground Thermo-Hydrological Changes In A Southern Tibetan Endorheic Catchment And Implications For Lake Level Changes. Hydrology And Earth System Sciences, 272(242), 4409–4436.
Abstract: Climate Change Modifies The Water And Energy Fluxes Between The Atmosphere And The Surface In Mountainous Regions Such As The Qinghai-Tibet Plateau (Qtp), Which Has Shown Substantial Hydrological Changes Over The Last Decades, Including Rapid Lake Level Variations. The Ground Across The Qtp Hosts Either Permafrost Or Is Seasonally Frozen, And, In This Environment, The Ground Thermal Regime Influences Liquid Water Availability, Evaporation And Runoff. Consequently, Climate-Induced Changes In The Ground Thermal Regime May Contribute To Variations In Lake Levels, But The Validity Of This Hypothesis Has Yet To Be Established.This Study Focuses On The Cryo-Hydrology Of The Catchment Of Lake Paiku (Southern Tibet) For The 1980-2019 Period. We Process Era5 Data With Downscaling And Clustering Tools (Toposcale, Toposub) To Account For The Spatial Variability Of The Climate In Our Forcing Data (Fiddes And Gruber, 2012, 2014). We Use A Distributed Setup Of The Cryogrid Community Model (Version 1.0) To Quantify Thermo-Hydrological Changes In The Ground During This Period. Forcing Data And Simulation Outputs Are Validated With Data From A Weather Station, Surface Temperature Loggers And Observations Of Lake Level Variations. Our Lake Budget Reconstruction Shows That The Main Water Input To The Lake Is Direct Precipitation (310 Mm Yr – 1 ), Followed By Glacier Runoff (280 Mm Yr – 1 ) And Land Runoff (180 Mm Yr – 1 ). However, Altogether These Components Do Not Offset Evaporation (860 Mm Yr – 1 ).Our Results Show That Both Seasonal Frozen Ground And Permafrost Have Warmed (0.17 Circle C Per Decade 2 M Deep), Increasing The Availability Of Liquid Water In The Ground And The Duration Of Seasonal Thaw. Correlations With Annual Values Suggest That Both Phenomena Promote Evaporation And Runoff. Yet, Ground Warming Drives A Strong Increase In Subsurface Runoff So That The Runoff / (Evaporation + Runoff) Ratio Increases Over Time. This Increase Likely Contributed To Stabilizing The Lake Level Decrease After 2010.Summer Evaporation Is An Important Energy Sink, And We Find Active-Layer Deepening Only Where Evaporation Is Limited. The Presence Of Permafrost Is Found To Promote Evaporation At The Expense Of Runoff, Consistently With Recent Studies Suggesting That A Shallow Active Layer Maintains Higher Water Contents Close To The Surface. However, This Relationship Seems To Be Climate Dependent, And We Show That A Colder And Wetter Climate Produces The Opposite Effect. Although The Present Study Was Performed At The Catchment Scale, We Suggest That This Ambivalent Influence Of Permafrost May Help To Understand The Contrasting Lake Level Variations Observed Between The South And North Of The Qtp, Opening New Perspectives For Future Investigations.
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Mathiot, P., & Jourdain, N. (2023). Southern Ocean Warming And Antarctic Ice Shelf Melting In Conditions Plausible By Late 23Rd Century In A High-End Scenario. Ocean Science, 191(6), 1595–1615.
Abstract: How Much Antarctic Ice Shelf Basal Melt Rates Can Increase In Response To Global Warming Remains An Open Question. Here We Describe The Response Of The Southern Ocean And Ice Shelf Cavities To An Abrupt Change To High-End Atmospheric Conditions Plausible By The Late 23Rd Century Under The Ssp5-8.5 Scenario. To Achieve This Objective, We First Present And Evaluate A New 0.25 Circle Global Configuration Of The Nemo Nucleus For European Modelling Of The Ocean Ocean And Sea Ice Model. Our Present-Day Simulations Demonstrate Good Agreement With Observational Data For Key Variables Such As Temperature, Salinity, And Ice Shelf Melt Rates, Despite The Remaining Difficulties To Simulate The Interannual Variability In The Amundsen Sea. The Ocean Response To The High-End Atmospheric Perturbation Includes A Strengthening And Extension Of The Ross And Weddell Gyres And A Quasi-Disappearance Of Sea Ice, With A Subsequent Decrease In Production Of High Salinity Shelf Water And Increased Intrusion Of Warmer Water Onto The Continental Shelves Favoured By Changes In Baroclinic Currents At The Shelf Break. We Propose To Classify The Perturbed Continental Shelf As A “Warm-Fresh Shelf”. This Induces A Substantial Increase In Ice Shelf Basal Melt Rates, Particularly In The Coldest Seas, With A Total Basal Mass Loss Rising From 1180 To 15 700 Gt Yr – 1 And An Antarctica Averaged Melt Rate Increasing From 0.8 To 10.6 M Yr – 1 . In The Perturbed Simulation, Most Ice Shelves Around Antarctica Experience Conditions That Are Currently Found In The Amundsen Sea, While The Amundsen Sea Warms By 2 Circle C. These Idealised Projections Can Be Used As A Base To Calibrate Basal Melt Parameterisations Used In Long-Term Ice Sheet Projections.
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Maure, D., Kittel, C., Lambin, C., Delhasse, A., & Fettweis, X. (2023). Spatially Heterogeneous Effect Of Climate Warming On The Arctic Land Ice. Cryosphere, 171(111), 4645–4659.
Abstract: Global Warming Has Already Substantially Altered The Arctic Cryosphere. Due To The Arctic Warming Amplification, The Temperature Is Increasing More Strongly, Leading To Pervasive Changes In This Area. Recent Years Were Notably Marked By Melt Records Over The Greenland Ice Sheet, While Other Regions Such As Svalbard Seem To Remain Less Influenced. This Raises The Question Of The Current State Of The Greenland Ice Sheet And The Various Ice Caps In The Arctic For Which Few Studies Are Available. Here, We Run The Regional Climate Model (Rcm) Modele Atmospherique Regional (Mar) At A Resolution Of 6 Km Over Four Different Domains Covering All Arctic Land Ice To Produce A Unified Surface Mass Balance Product From 1950 To The Present Day. We Also Compare Our Results To Large-Scale Indices To Better Understand The Heterogeneity Of The Evolutions Across The Arctic And Their Links To Recent Climate Change. We Find A Sharp Decrease Of Surface Mass Balance (Smb) Over The Western Arctic (Canada And Greenland) In Relationship With The Atmospheric Blocking Situations That Have Become More Frequent In Summer, Resulting In A 41 % Increase Of The Melt Rate Since 1950. This Increase Is Not Seen Over The Russian Arctic Permanent Ice Areas, Where Melt Rates Have Increased By Only 3 % On Average, Illustrating A Heterogeneity In The Arctic Smb Response To Global Warming.
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Mentani, A., Govoni, L., Bourrier, F., & Zabatta, R. (2023). Metamodelling Of The Load-Displacement Response Of Offshore Piles In Sand. Computers And Geotechnics, .
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Menut, L., Cholakian, A., Siour, G., Lapere, R., Pennel, R., Mailler, S., et al. (2023). Impact Of Landes Forest Fires On Air Quality In France During The 2022 Summer. Atmospheric Chemistry And Physics, , 728177–729677.
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Metref, S., Cosme, E., Le Lay, M., & Gailhard, J. (2023). Snow Data Assimilation For Seasonal Streamflow Supply Prediction In Mountainous Basins. Hydrology And Earth System Sciences, , 228322–229922.
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Milojevic, T., Blanchet, J., & Lehning, M. (2023). Determining Return Levels Of Extreme Daily Precipitation, Reservoir Inflow, And Dry Spells. Frontiers In Water, 5.
Abstract: Return Level Calculations Are Widely Used To Determine The Risks That Extreme Events May Pose To Infrastructure, Including Hydropower Site Operations. Extreme Events (E.G., Extreme Precipitation And Droughts) Are Expected To Increase In Frequency And Intensity In The Future, But Not Necessarily In A Homogenous Way Across Regions. This Makes Localized Assessment Important For Understanding Risk Changes To Specific Sites. However, For Sites With Relatively Small Datasets, Selecting An Applicable Method For Return Level Calculations Is Not Straightforward. This Study Focuses On The Application Of Traditional Univariate Extreme Value Approaches (Generalized Extreme Value And Generalized Pareto) As Well As Two More Recent Approaches (Extended Generalized Pareto And Metastatistical Extreme Value Distributions), That Are Specifically Suited For Application To Small Datasets. These Methods Are Used To Calculate Return Levels Of Extreme Precipitation At Six Alpine Stations And High Reservoir Inflow Events For A Hydropower Reservoir. In Addition, Return Levels Of Meteorological Drought And Low Inflow Periods (Dry Spells) Are Determined Using A Non-Parametric Approach. Return Levels For Return Periods Of 10- And 20- Years Were Calculated Using 10-, 20-, And 40- Years Of Data For Each Method. The Results Show That Even Shorter Timeseries Can Give Similar Return Levels As Longer Timeseries For Most Methods. However, The Gev Has Greater Sensitivity To Sparse Data And Tended To Give Lower Estimates For Precipitation Return Levels. The Mev Is Only To Be Preferred Over Gpd If The Underlying Distribution Fits The Data Well. The Result Is Used To Assemble A Profile Of 10- And 20-Year Return Levels Estimated With Various Statistical Approaches, For Extreme High Precipitation/Inflow And Low Precipitation/Inflow Events. The Findings Of The Study May Be Helpful To Researchers And Practitioners Alike In Deciding Which Statistical Approach To Use To Assess Local Extreme Precipitation And Inflow Risks To Individual Reservoirs.
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Molina-Carpio, J., Rivera, I., Espinoza-Romero, D., Ceron, W., Espinoza, J., & Ronchail, J. (2023). Regionalization Of Rainfall In The Upper Madeira Basin Based On Interannual And Decadal Variability: A Multi-Seasonal Approach. International Journal Of Climatology, .
Abstract: Identifying Rainfall Regions Associated With Specific Modes Of Variability Is Of Practical Interest For Water Resources Management, Seasonal Forecasting, And Mitigation Of Weather-Related Risks. This Study Aims To Identify Homogeneous Rainfall Regions Within The Similar To 1 Million Km(2) Upper Madeira River Basin-Southwestern Amazon-By Their Interannual And Decadal Variability And Relates This Variability To Ocean Indices. An Observed Dataset Of 146 Ground-Based Rainfall Stations, Distributed Throughout The Andes And The Amazon, And Homogenized At The Monthly Time-Step For The Period 1980-2016, Was Used For The Analysis. With No Spatial Constraints, Hierarchical Cluster Analysis And Principal Component Analysis (Pca) Optimally Grouped Stations Into 10 Rainfall Homogenous Regions. The Value Of The Regionalization For Interpreting The Rainfall Variability Was Evaluated By Relating The Seasonal Rainfall Time Series Of The Regions With Ocean Indices. Then, By Applying Pca To Seasonal Rainfall Series And Linking The Principal Components To Sea Surface Temperature And Ocean Indices, An Insight Into The Main Large-Scale Drivers Of The Rainfall Spatio-Temporal Variability In This Basin At Interannual And Decadal Scales Is Provided. This Analysis Identified Differences In The Year-Round Influences Of The Tropical Pacific And/Or Atlantic Oceans On The 10 Homogenous Regions.
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Molina-Carpio, J., Rivera, I., Espinoza-Romero, D., Cerón, W., Espinoza, J., & Ronchail, J. (2023). Regionalization Of Rainfall In The Upper Madeira Basin Based On Interannual And Decadal Variability: A Multi-Seasonal Approach. International Journal Of Climatology, 434(141), 6402–6419.
Abstract: Identifying Rainfall Regions Associated With Specific Modes Of Variability Is Of Practical Interest For Water Resources Management, Seasonal Forecasting, And Mitigation Of Weather-Related Risks. This Study Aims To Identify Homogeneous Rainfall Regions Within The Similar To 1 Million Km(2) Upper Madeira River Basin-Southwestern Amazon-By Their Interannual And Decadal Variability And Relates This Variability To Ocean Indices. An Observed Dataset Of 146 Groundbased Rainfall Stations, Distributed Throughout The Andes And The Amazon, And Homogenized At The Monthly Time-Step For The Period 1980-2016, Was Used For The Analysis. With No Spatial Constraints, Hierarchical Cluster Analysis And Principal Component Analysis (Pca) Optimally Grouped Stations Into 10 Rainfall Homogenous Regions. The Value Of The Regionalization For Interpreting The Rain-Fall Variability Was Evaluated By Relating The Seasonal Rainfall Time Series Of The Regions With Ocean Indices. Then, By Applying Pca To Seasonal Rainfall Series And Linking The Principal Components To Sea Surface Temperature And Ocean Indices, An Insight Into The Main Large-Scale Drivers Of The Rainfall Spatio-Temporal Variability In This Basin At Interannual And Decadal Scales Is Provided. This Analysis Identified Differences In The Year-Round Influences Of The Tropical Pacific And/Or Atlantic Oceans On The 10 Homogenous Regions.
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Morel, M., Piton, G., Kuss, D., Evin, G., & Le Bouteiller, C. (2023). Statistical Modeling Of Sediment Supply In Torrent Catchments Of The Northern French Alps. Natural Hazards And Earth System Sciences, , 176911–178711.
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Moron, V., Camberlin, P., Aellig, R., Champagne, O., Fink, A., Knippertz, P., et al. (2023). Diurnal To Interannual Variability Of Low-Level Cloud Cover Over Western Equatorial Africa In May-October. International Journal Of Climatology, .
Abstract: This Study Examines The Diurnal To Interannual Variations Of The Stratiform Cloud Cover In May-October (1971-2019) From A 3-Hourly Station Database And From Era5 Reanalyses Over Western Equatorial Africa (Wea). The Main Diurnal Variations Of The Local-Scale Fraction And Genus Of Stratiform Clouds Are Synthesized Into Three Canonical Diurnal Types (I.E., “Clear,” “Clear Afternoon,” “Cloudy” Days). The Interannual Variations Of Frequencies Of The Three Diurnal Types During The Cloudiest Months (Jjas) Are Mostly Associated With Two Main Mechanisms: A Meridional Shallow Overturning Cell Associating More “Cloudy” And Less “Clear” And “Clear Afternoon” Days To Anomalous Southerlies Below 900 Hpa Over And Around Wea, Anomalous Ascent Around 5 Degrees-7 Degrees N, Anomalous Northerlies Between 875 And 700 Hpa, And Anomalous Subsidence Over The Equatorial Atlantic. This Circulation Is Strongly Related To Interannual Variations Of The Equatorial Atlantic Upwelling (I.E., More Clouds When The Upwelling Is Strong) Associated With A Meridional Shift Of The Intertropical Convergence Zone Over The Tropical Atlantic And Adjacent Continents. The Second Mechanism Operates Mostly In The Zonal Direction And Involves Again The Coupled Ocean-Atmosphere System Over The Equatorial Atlantic, But Also The Remote El Nino-Southern Oscillation (Enso). An Anomalously Cold Equatorial Atlantic Drives Increased Low-Level Westerlies Toward The Congo Basin. Warm Enso Events Promote Broad Warm And Easterly Anomalies In The Middle And Upper Troposphere, Which Increase The Local Static Stability, And Thus The Local Stratiform Cloud Cover Over Wea. The Present Study Suggests New Mechanisms Responsible For Interannual Variations Of Stratiform Clouds In Wea, Thus Providing Avenues Of Future Research Regarding The Stability Of The Stratiform Cloud Deck Under The Ongoing Differential Warming Of Tropical Ocean And Land Masses.
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Mosbeux, C., Padman, L., Klein, E., Bromirski, P., & Fricker, H. (2023). Seasonal Variability In Antarctic Ice Shelf Velocities Forced By Sea Surfaceheight Variations. Cryosphere, , 258522–260622.
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Mouginot, J., Rabatel, A., Ducasse, E., & Millan, R. (2023). Optimization Of Cross Correlation Algorithm For Annual Mapping Of Alpine Glacier Flow Velocities; Application To Sentinel-2. Ieee Transactions On Geoscience And Remote Sensing, 616.
Abstract: Nowadays, Satellite Observations Cover Most Of The Earth'S Surface In A Repetitive Manner. This Information Is Crucial For Documenting Variability And Environmental Changes Such As Glacier Surface Velocity. With This In Mind, Digital Image Processing Has Been Developed And Improved Over The Past Decades. The Processing Challenges Are Now Related To Optimizing Parameters That Account For The High Variability Of Natural Processes, As Well As Filtering And Aggregating The Results To Provide Useful Products To End-Users. Based On The Normalized Cross Correlation (Ncc) Method Applied To Sentinel-2 Optical Satellite Observations Up To 400 Days Apart, We Present A Series Of Tests To Derive Optimal Parameter Values For The Quantification Of Alpine Glacier Ice Velocity That We Have Applied To The Mont-Blanc Massif Where In Situ Measurements Are Available. We Found That A Search Distance Adapted To The Temporal Baseline, A 16X16 Pixel Window Size, And A 5X5 Pixels Sampling Provide An Appropriate Combination Of Parameters To Process Sentinel-2 With The Ncc Method When Applied To Small Alpine Glaciers. Combining Several Spatial And Temporal Filters Applied To A Large Set Of More Than 18 000 Displacement Maps Obtained Between 2015 And 2021, Then Aggregating These Filtered Maps Using Statistical Or Linear Regressions Into Annual Maps, Yields Near-Complete Maps Of The Test Region With A Root Mean Square Error (Rmse) Reduced To About 10 M.Yr(-1) Compared To In Situ Measurements.
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Mulvaney, R., Wolff, E., Grieman, M., Hoffmann, H., Humby, J., Nehrbass-Ahles, C., et al. (2023). The St22 Chronology For The Skytrain Ice Rise Ice Core – Part 2: An Age Model To The Last Interglacial And Disturbed Deep Stratigraphy. Climate Of The Past, , 85188–86488.
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Murfitt, J., Duguay, C., Picard, G., & Gunn, G. (2023). Forward Modelling Of Synthetic Aperture Radar Backscatter From Lake Ice Over Canadian Subarctic Lakes. Remote Sensing Of Environment, 2862.
Abstract: Lake Ice Provides Important Social And Economic Services To Local Communities, In Addition To Being A Sensitive Indicator Of Climate Change. The Reduction Of Ground Observations Of Freshwater Ice Has Led To An Increased Reliance On The Use Of Satellite Remote Sensing Data. There Is Currently Interest In The Retrieval Of Lake Ice Properties (E.G., Ice Thickness, Bubble Radius, Roughness) Using Synthetic Aperture Radar (Sar). Roughness At The Ice-Water Interface Is Particularly Important As It Has Been Identified As The Dominant Mechanism For Increasing Sar Backscatter Throughout The Ice Season And Must Be Considered In Numerical Radiative Transfer Models. Therefore, This Study Determines Optimal Ice-Water Interface Roughness Height For Two Subarctic Lakes In Northern Canada And Models Backscatter Throughout Two Ice Seasons Using The Snow Microwave Radiative Transfer (Smrt) Model. The Two Lakes For This Study Are Noell Lake And Malcolm Ramsay Lake. Field Observations Of Ice Thickness, Snow Depth, Snow Density, And The Canadian Lake Ice Model (Climo) Are Used To Parameterize Smrt. Modelled L, C, And X-Band Backscatter At Different Incidence Angles Is Assessed Using Sar Imagery From Multiple Satellite Missions. Root Mean Square Errors Ranged From 0.38 To 1.45 Db For Noell Lake And 0.70 To 2.33 Db For Malcolm Ramsay Lake. Discrepancies Between Modelled And Observed Backscatter Were Found To Be Connected To The Representation Of Roughness At Different Interfaces Within The Ice Column And Changes That Occurred During Freeze-Melt Events. These Results Provide Insight Into How Changes In Ice Properties Impact Backscatter Throughout The Ice Season. Smrt Is Valuable For Modelling Backscatter From Lake Ice During The Cold Season And Could Be Used To Develop Retrieval Algorithms For Estimating Ice-Water Interface Roughness. This Would Allow For The Development Of Other Inversion Models For Retrieval Of Surface Ice Conditions And Ice Thickness.
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Nanni, U., Scherler, D., Ayoub, F., Millan, R., Herman, F., & Avouac, J. (2023). Climatic Control On Seasonal Variations In Mountain Glacier Surface Velocity. Cryosphere, 171(4), 1567–1583.
Abstract: Accurate Measurements Of Ice Flow Are Essential To Predict Future Changes In Glaciers And Ice Caps. Glacier Displacement Can In Principle Be Measured On The Large Scale By Cross-Correlation Of Satellite Images. At Weekly To Monthly Scales, The Expected Displacement Is Often Of The Same Order As The Noise For The Commonly Used Satellite Images, Complicating The Retrieval Of Accurate Glacier Velocity. Assessments Of Velocity Changes On Short Timescales And Over Complex Areas Such As Mountain Ranges Are Therefore Still Lacking But Are Essential To Better Understand How Glacier Dynamics Are Driven By Internal And External Factors. In This Study, We Take Advantage Of The Wide Availability And Redundancy Of Satellite Imagery Over The Western Pamirs To Retrieve Glacier Velocity Changes Over 10 D Intervals For 7 Years And For A Wide Range Of Glacier Geometry And Dynamics. Our Results Reveal Strong Seasonal Trends. In Spring/Summer, We Observe Velocity Increases Of Up To 300 % Compared To A Slow Winter Period. These Accelerations Clearly Migrate Upglacier Throughout The Melt Season, Which We Link To Changes In Subglacial Hydrology Efficiency. In Autumn, We Observe Glacier Accelerations That Have Rarely Been Observed Before. These Episodes Are Primarily Confined To The Upper Ablation Zone With A Clear Downglacier Migration. We Suggest That They Result From Glacier Instabilities Caused By Sudden Subglacial Pressurization In Response To (1) Supraglacial Pond Drainage And/Or (2) Gradual Closure Of The Hydrological System. Our 10 D Resolved Measurements Allow Us To Characterize The Short-Term Response Of Glaciers To Changing Meteorological And Climatic Conditions.
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Neubauer, C., Kantnerova, K., Lamothe, A., Savarino, J., Hilkert, A., Juchelka, D., et al. (2023). Discovering Nature?S Fingerprints: Isotope Ratio Analysis On Bioanalytical Mass Spectrometers. Journal Of The American Society For Mass Spectrometry, 343(4), 525–537.
Abstract: For A Generation Or More, The Mass Spectrometry That Developed At The Frontier Of Molecular Biology Was Worlds Apart From Isotope Ratio Mass Spectrometry, A Label-Free Approach Done On Optimized Gas-Source Magnetic Sector Instruments. Recent Studies Show That Electrospray-Ionization Orbitraps And Other Mass Spectrom-Eters Widely Used In The Life Sciences Can Be Fine-Tuned For High-Precision Isotope Ratio Analysis. Since Isotope Patterns Form Everywhere In Nature Based On Well-Understood Principles, Intramolecula R Isotope Measure-Ments Allow Unique Insights Into A Fascinating Range Of Research Topics. This Perspective Introduces A Wider Readership To Current Topics In Stable Isotope Research With The Aim Of Discussing How Soft-Ionization Mass Spectrometry Coupled With Ultrahigh Mass Resolution Can Enable Long-Envisioned Progress. We Highlight Novel Prospects Of Observing Isotopes In Intact Polar Compounds And Speculate On Future Directions Of This Adventure Into The Overlapping Realms Of Biology, Chemistry, And Geology.
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Nguyen, T., & Baduel, C. (2023). Optimization And Validation Of An Extraction Method For The Analysis Of Multi-Class Emerging Contaminants In Soil And Sediment. Journal Of Chromatography A, 17101.
Abstract: Analytical Methods For The Determination Of Multi-Class Emerging Contaminants Are Limited For Soil And Sediment While They Are Essential To Provide A More Complete Picture Of Their Distribution In The Environment And To Understand Their Fate In Different Environmental Compartments. In This Paper, We Present The Development And Optimization Of An Analytical Strategy That Combines Reliable Extraction, Purification And The Analysis Using Ultrapressure Liquid Chromatography Triple Quadrupole Mass Spectrometry (Uplc-Ms/Ms) Of 90 Emerging Organic Contaminants Including Pesticides, Pharmaceuticals And Personal Care Products, Flame Retardants, Per- And Polyfluoroalkyl Substances (Pfass) And Plasticizers In Soil And Sediment. To Extract A Wide Range Of Chemicals, The Extraction Strategy Is Based On The Quechers (Quick, Easy, Cheap, Effective, Rugged And Safe) Approach. A Number Of Different Options Were Investigated (Buffer, Acidification, Addition Of Edta, Different Types And Combinations Of Dispersive Spe Etc.) And The Effectiveness Of The Chemical Extraction Procedure And The Clean-Up Was Assessed For Two Matrices: Soil (Organic Matter Content Of 9%) And Sediment (Organic Matter Content Of 1.9%). The Method Was Fully Validated For Both Matrices, In Terms Of Accuracy, Linearity, Repeatability (Intraday), Reproducibility (Inter-Day), Method Limits Of Detection And Quantification (Lods And Mloqs, Respectively). The Final Performance Showed Good Accuracy And Precision (Mean Recoveries Were Between 70 And 120% With Relative Standard Deviations (Rsd) Less Than 20% In Most Cases), Low Matrix Effects, Good Linearity For The Matrixmatched Calibration Curve (R2 >= 0.991) And Mloqs Ranged From 0.25 And 10 Mu G/Kg. To Demonstrate The Applicability And Suitability Of The Validated Method, Soil And Sediment Samples From Vietnam, France, Sweden And Mexico Were Analyzed. The Results Showed That Of The 90 Target Compounds, A Total Of 33 Were Quantified In The Sediment And Soil Samples Analyzed. In Addition To Multi-Target Analysis, This Strategy Could Be Suitable For Nontarget Screening, To Provide A More Comprehensive View Of The Contaminants Present In The Samples.
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Nitzbon, J., Krinner, G., Von Deimling, T., Werner, M., & Langer, M. (2023). First Quantification Of The Permafrost Heat Sink In The Earth'S Climate System. Geophysical Research Letters, .
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Obahoundje, S., Nguessan-Bi, V., Diedhiou, A., Kravitz, B., & Moore, J. (2023). Implication Of Stratospheric Aerosol Geoengineering On Compound Precipitation And Temperature Extremes In Africa. Science Of The Total Environment, 8638.
Abstract: Three Coupled Model Intercomparison Project 5 (Cmip5) Models That Simulated The G4 Experiment Of The Geoengineering Model Intercomparison Project (Geomip) Were Used To Investigate The Impact Of Stratospheric Aerosol Injection (Sai) On Combined Temperature And Precipitation Extremes In Africa That Can Have Greater Negative Impacts On Human And The Environment Than Individual Rainfall Or Temperature Extremes. The Examined Compound Extremes Included The Dry (R-Warm Vertical Bar Dry And R-Cold Vertical Bar Dry) And Wet (R-Warm Vertical Bar Wet And R-Cold Vertical Bar Wet) Modes Assessed During The Injection (Sai, 2050-2069) And Post-Injection (Postsai, 2070-2089) Periods Compared With The Historical Period (1986-2005). We Found A Significant Projected Change In The Occurrence Of Both Wet And Dry Modes During Sai And Postsai Related To The Historical Period. The Magnitude And Sign Of This Change Depend On The Season And The Geographical Location. During The Sai And Postsai, The Wet (R-Warm Vertical Bar Wet And R-Cold Vertical Bar Wet) Modes Are Projected To Be Significantly Lower While The Dry Modes Are Noted To Increase In A Large Part Of African Continent Depending On The Season And The Geographical Location And May Consequently Leads To An Increase Of The Droughts Prone Areas. The Termination Effect Is Noted To Reduce The Occurrence Of Dry Modes, Which May Reduce The Potential Negative Effects Of The Injection After Halting. As The Effect May Vary From One Region To Another And According To The Season, It Suggested Assessing The Key Sector Impacts Of Sai. Thus, This Change In Dry Modes Due To Sai Could Affect All Activities Which Depend On Water Resources Such As Water Supply, Agriculture And Food Production, Energy Demand, And Production With Adverse Effects On Health, Security, And Sustainable Development, But This Needs To Be Assessed And Quantified At Regional Scales.
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Otosaka, I., Shepherd, A., Ivins, E., Schlegel, N., Amory, C., Van Den Broeke, M., et al. (2023). Mass Balance Of The Greenland And Antarctic Ice Sheets From 1992 To 2020. Earth System Science Data, , 159711–161611.
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Ouhechou, A., Philippon, N., Morel, B., Trentmann, J., Graillet, A., Mariscal, A., et al. (2023). Inter-Comparison And Validation Against In-Situ Measurements Of Satellite Estimates Of Incoming Solar Radiation For Central Africa: From The Annual Means To The Diurnal Cycles. Atmospheric Research, 2872.
Abstract: This Study Pictures For The First Time Incoming Solar Radiation Mean Evolution In Central Africa, Intercomparing 8 Gridded Products (Namely Ceres-Ebaf, Ceres-Syn1Deg, Tpdc, Cmsaf Sarah-2, Cmsaf Clara-A2, Cams -Jade Satellite Products, As Well As Era5 Reanalysis And Worldclim 2 Interpolated Measurements) And Station -Based Estimations (Faoclim 2) Or Measurements. At The Mean Annual Scale, All Products Picture Low Levels Of Global Horizontal Irradiance (Ghi) To The West (Sw Cameroon To Sw Republic Of Congo) And Higher Levels To-Wards The North And South Margins Of The Region. However, Ghi Levels In The Cmsaf Products Are Much Higher Than In Ceres And Tpdc. The Mean Annual Cycles Of Ghi Extracted For 6 Sub-Regions Are Bimodal, With Two Maxima During The Two Rainy Seasons (March-May And September-November) And Two Minima During The Two Dry Seasons (December-February And June-August). These Seasonal Cycles Are Well Reproduced By Most Products Except Their Amplitude Which Is Dampened In Tpdc. At The Daily And Sub-Daily Time-Scales, Products Were Compared With In-Situ Measurements From Ten Meteorological Stations Located In The Western Part Of Central Africa. The Products' Performance Is Assessed Through Scores As Bias And Rmse But Also By Considering The Diurnal Cycles' Shape, Amplitude And Frequency Of Occurrence Along The Annual Cycle. The Products Properly Reproduce The Shape Of The Four Types Of Diurnal Cycles With Nonetheless Noticeable Differences In The Cycle'S Frequencies Of Occurrence.
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Ousmane, B., Nazoumou, Y., Favreau, G., Babaye, M., Mahaman, R., Boucher, M., et al. (2023). Groundwater Quality And Its Implications For Domestic And Agricultural Water Supplies In A Semi-Arid River Basin Of Niger. Environmental Earth Sciences, .
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Ousset, I., Evin, G., Raynaud, D., & Faug, T. (2023). Back Analysis Of A Building Collapse Under Snow And Rain Loads In A Mediterranean Area. Natural Hazards And Earth System Sciences, 232(111), 3509–3523.
Abstract: At The End Of February 2018 The Mediterranean Area Of Montpellier In France Was Struck By A Significant Snowfall That Turned Into An Intense Rain Event Caused By An Exceptional Atmospheric Situation. This Rain-On-Snow Event Produced Pronounced Damage To Many Buildings Of Different Types. In This Study, We Report A Detailed Back Analysis Of The Roof Collapse Of A Large Building, Namely Irstea Cevennes. Attention Is Paid To The Dynamics Of The Climatic Event, On The One Hand, And The Mechanical Response Of The Metal Roof Structure To Different Snow And Rain Loads, On The Other Hand. The Former Aspect Relies On Multiple Sources Of Information That Provide Reliable Estimates Of Snow Heights In The Area Before The Rain Came Into Play And Substantially Modified The Load On The Roof. The Latter Aspect Relies On Detailed Finite-Element Simulations Of The Mechanical Behavior Of The Roof Structure In Order To Assess The Pressure Due To Snow And Rain Loading, Which Could Theoretically Lead To Failure. By Combining The Two Approaches, It Is Possible To Reconstruct The Most Probable Scenario For The Roof Failure Before Its Full Collapse. As An Example Of Building Behavior And Vulnerability To An Atypical Rain-On-Snow Event In The Mediterranean Area Of France, This Detailed Case Study Provides Useful Key Points To Be Considered In The Future For A Better Mitigation Of Such Events In Non-Mountainous Areas.
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Oyabu, I., Kawamura, K., Fujita, S., Inoue, R., Motoyama, H., Fukui, K., et al. (2023). Temporal Variations Of Surface Mass Balance Over The Last 5000 Years Around Dome Fuji, Dronning Maud Land, East Antarctica. Climate Of The Past, 191(2), 293–321.
Abstract: We Reconstructed Surface Mass Balance (Smb) Around Dome Fuji, Antarctica, Over The Last 5000 Years Using The Data From 15 Shallow Ice Cores And Seven Snow Pits. The Depth-Age Relationships For The Ice Cores Were Determined By Synchronizing Them With A Layer-Counted Ice Core From West Antarctica (Wais Divide Ice Core) Using Volcanic Signals. The Reconstructed Smb Records For The Last 4000 Years Show Spatial Patterns That May Be Affected By Their Locations Relative To The Ice Divides Around Dome Fuji, Proximity To The Ocean, And Wind Direction. The Smb Records From The Individual Ice Cores And Snow Pits Were Stacked To Reconstruct The Smb History In The Dome Fuji Area. The Stacked Record Exhibits A Long-Term Decreasing Trend At -0.037 +/- 0.005 Kg M(-2) Per Century Over The Last 5000 Years In The Preindustrial Period. The Decreasing Trend May Be The Result Of Long-Term Surface Cooling Over East Antarctica And The Southern Ocean And Sea Ice Expansion In The Water Vapor Source Areas. The Multidecadal To Centennial Variations Of The Dome Fuji Smb After Detrending The Record Shows Four Distinct Periods During The Last Millennium: A Mostly Negative Period Before 1300 Ce, A Slightly Positive Period From 1300 To 1450 Ce, A Slightly Negative Period From 1450 To 1850 Ce With A Weak Maximum Around 1600 Ce, And A Strong Increase After 1850 Ce. These Variations Are Consistent With Those Of Previously Reconstructed Smb Records In The East Antarctic Plateau. The Low Accumulation Rate Periods Tend To Coincide With The Combination Of Strong Volcanic Forcings And Solar Minima For The Last 1000 Years, But The Correspondence Is Not Clear For The Older Periods, Possibly Because Of The Lack Of Coincidence Of Volcanic And Solar Forcings Or The Deterioration Of The Smb Record Due To A Smaller Number Of Stacked Cores.
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Pachoud, C., Bruley, E., Grosinger, J., Crepeau, A., Salim, E., Savre, C., et al. (2023). Joint Problem Framing: A Transdisciplinary Methodology For A Sustainable Future In Mountain Areas. Sustainability Science, .
Abstract: Investigating The Sustainability Of Social-Ecological Systems In The Context Of Climatic, Economic And Social Changes Requires Novel Science Practises. Transdisciplinary Research (Tdr) Presents An Interesting Approach On How Science Can Interact With Society In Finding Meaningful Answers To Wicked Problems. Social-Ecological Systems In Mountain Areas Are Particularly Relevant Not Only Because Of Their Serious Vulnerability To Global Changes But Also Because Of Their Efforts To Move Towards Sustainability. The Researchers' Collective Perce-Neige Strives To Tackle These Challenges And Applies Novel Transdisciplinary Approaches. The Collective Is Composed Of Early Career Researchers Coming From Various Disciplines, Working On Sustainable Transitions In Mountains. For A Week, 12 Early Career Researchers Conducted Tdr For Joint Problem Framing With Inhabitants And Local Institutions Of The Municipality Of Gresse-En-Vercors In The French Alps. The Objective Was To Facilitate The Development Of A Common Vision And Initiate Collective Thinking For A Sustainable Future Of The Territoire. Participants (Researchers And Inhabitants) Became Acquainted With Each Other Through Different Interfaces Facilitating Exchanges, Reflections And Co-Constructions (Collective Walk, Individual Interviews, Participatory Workshops, Informal Daily Exchanges). The Research Allowed Us To Capture Different Perspectives On Local Issues That Cause Conflicts, And Then To Discuss And Identify Needs And Solutions. We Aim To Present And Assess The Methodology For Joint Problem Framing Developed By The Collective. This Paper Presents The Benefits Of Such A Methodology For Acculturating Early Career Researchers To Tdr, And For Framing Societal Problems And Reflecting On Actions.
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Paolini, G., Escorihuela, M., Merlin, O., Laluet, P., Bellvert, J., & Pellarin, T. (2023). Estimating Multi-Scale Irrigation Amounts Using Multi-Resolution Soil Moisture Data: A Data-Driven Approach Using Prism. Agricultural Water Management, 2902.
Abstract: Irrigated Agriculture Is The Primary Driver Of Freshwater Use And Is Continuously Expanding. Precise Knowledge Of Irrigation Amounts Is Critical For Optimizing Water Management, Especially In Semi-Arid Regions Where Water Is A Limited Resource. This Study Proposed To Adapt The Prism (Precipitation Inferred From Soil Moisture) Method-Ology To Detect And Estimate Irrigation Events From Soil Moisture Remotely Sensed Data. Prism Was Originally Conceived To Correct Precipitation Products, Assimilating Soil Moisture (Sm) Observations Into An Antecedent Precipitation Index (Api) Formula, Using A Particle Filter Scheme. This Novel Application Of Prism Uses Initial Precipitation And Sm Observations To Detect Instances Of Water Excess In The Soil (Not Caused By Precipitation) And Estimates The Amount Of Irrigation, Along With Its Uncertainty. This Newly Proposed Approach Does Not Require Extensive Calibration And Is Adaptable To Different Spatial And Temporal Scales. The Objective Of This Study Was To Analyze The Performance Of Prism For Irrigation Amount Estimation And Compare It With Current State-Of-The-Art Approaches. To Develop And Test This Methodology, A Synthetic Study Was Conducted Using Sm Observations With Various Noise Levels To Simulate Uncertainties And Different Spatial And Temporal Resolutions. The Results Indicated That A High Temporal Resolution (Less Than 3 Days) Is Crucial To Avoid Underestimating Irrigation Amounts Due To Missing Events. However, Including A Constraint On The Frequency Of Irrigation Events, Deduced From The System Of Irrigation Used At The Field Level, Could Overcome The Limitation Of Low Temporal Resolution And Significantly Reduce Underestimation Of Irrigation Amounts. Subsequently, The Developed Methodology Was Applied To Actual Satellite Sm Products At Different Spatial Scales (1 Km And 100 M) Over The Same Area. Validation Was Performed Using In Situ Data At The District Level Of Algerri-Balaguer In Catalunya, Spain, Where In Situ Irrigation Amounts Were Available For Various Years. The Validation Resulted In A Total Pearson'S Correlation Coefficient (R) Of 0.80 And A Total Root Mean Square Error (Rmse) Of 7.19 Mm/Week For The Years From 2017 To 2021. Additional Vali-Dation Was Conducted At The Field Level In The Segarra-Garrigues Irrigation District Using In Situ Data From A Field Where Sm Profiles And Irrigation Amounts Were Continuously Monitored. This Validation Yielded A Total Bi-Weekly R Of 0.81 And A Total Rmse Of-9.34 Mm/14-Days For The Years From 2017 To 2021. Overall, The Results Suggested That Prism Can Effectively Estimate Irrigation From Sm Remote Sensing Data, And The Methodology Has The Po-Tential To Be Applied On A Large Scale Without Requiring Extensive Calibration Or Site-Specific Knowledge.
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Piantini, M., Gimbert, F., Korkolis, E., Rousseau, R., Bellot, H., & Recking, A. (2023). Solid Concentration As A Main Proxy For Basal Force Fluctuations Generated By Highly Concentrated Sediment Flows. Geophysical Research Letters, 505(1).
Abstract: Sediment Flows Generate Ground Vibrations By Exerting Force Fluctuations On The Riverbed. Linking Force Fluctuations To Properties Of Highly Concentrated Sediment Flows, However, Remains Particularly Challenging Due To Complexities Arising From Grain-To-Grain Interactions. Here, We Conduct Downscaled Flume Experiments In Which We Specifically Measure Force Fluctuations And Local Seismic Vibrations Together With Flow Properties Of Highly Concentrated Sediment Flows At High Spatial And Temporal Resolution. We Observe Hysteresis Behaviors Between Force Fluctuations Amplitude And Flow Surface Elevation And Mass That Occur During Complex Changes In Internal Flow Dynamics. By Contrast, Force Fluctuations Amplitude Exhibits A Unique Negative Relationship With Solid Concentration. We Suggest This Is Due To The Rheology Of Dense Granular Flows, Where Solid Concentration Is A Proxy For Particle Agitation. We Therefore Advance That Solid Concentration Should Be Incorporated In Seismic Models Of Such Sediment Flows As A Key Parameter Describing Inter-Particle Collisions And Impacts To The Bed.
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Piantini, M., Gimbert, F., Korkolis, E., Rousseau, R., Bellot, H., & Recking, A. (2023). Solid Concentration As A Main Proxy For Basal Force Fluctuations Generated By Highly Concentrated Sediment Flows. Geophysical Research Letters, .
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Pimentel, R., Arheimer, B., Crochemore, L., Andersson, J., Pechlivanidis, I., & Gustafsson, D. (2023). Which Potential Evapotranspiration Formula To Use In Hydrological Modeling World-Wide? Water Resources Research, .
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Pimentel, R., Crochemore, L., Andersson, J., & Arheimer, B. (2023). Assessing Robustness In Global Hydrological Predictions By Comparing Modelling And Earth Observations. Hydrological Sciences Journal, .
Abstract: Hydrological Modelling To Support Hypotheses On Earth System Boundaries Or The Accelerating Water Crisis Is Nowadays Done At The Global Scale, With Difficulties Associated To Model Uncertainties. Here We Bring A Robustness Analysis Of Internal Model Variables As An Additional Tool For Model Evaluation Using Data From Six Earth Observation Products And The Global Catchment Model World-Wide Hype In A Comparative Study. The Assessment Shows That: (I) Variables Have High Agreement In Mid-Latitude Temperate Regions; (Ii) The Variables With Higher Agreement, And Associated With Good Model Performance In Streamflow, Were Actual Evapotranspiration, Fractional Snow Cover And Snow Water Equivalent; And (Iii) Changes In Total Water Storage Showed Very Poor Agreement, Probably Due To An Insufficient Number Of Aquifers In The Model Set-Up. We Propose This Procedure As A Standard Complementary Method In Global Hydrological Modelling, Highlighting The Importance Of Justifying Models Before Using Them For Scenario Analysis Or Water Accounting.
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Piton, G., Mayo, A., & Lambert, S. (2023). Small-Scale Modeling Of Flexible Barriers. Ii: Interactions With Large Wood. Journal Of Hydraulic Engineering, 1491(3).
Abstract: During Strong Floods, Rivers Often Carry Significant Amounts Of Sediment And Pieces Of Large Wood (Lw). When Bridges And Hydraulic Structures Are Unable To Allow Lw To Pass Through, It Becomes Necessary To Trap Lw Through Specific Wood Retention Structures (E.G., Flexible Barriers). This Paper Presents A Comprehensive Analysis Of The Interactions Between Lw And Flexible Barriers Using Small Scale Models. A Dimensionless Criterion Is First Proposed To Compute Blockage Probability Of Single Logs. It Is Based On Experiments Varying Log Size And Shape, Channel Slope (2%, 4%, And 6%), Water Discharge, And Barrier Bottom Clearance. Based On Runs Using Six Mixtures Of Hundreds Of Logs, An Equation Is Secondly Provided To Compute Flow Depth At A Barrier Accounting For The Head Losses Related To Large Numbers Of Logs. Conditions Leading To The Release Of Lw When The Barrier Is Severely Overwhelmed Are Also Studied. The Deformation Measured On The Barrier Proves To Be Lower With Lw-Laden Flows Than Under Full Hydrostatic Loading Of A Barrier Obstructed By A Plastic Sheet. Overall, We Demonstrate That Flexible Barriers Are Very Relevant Structures To Trap Lw. A Companion Paper Shows How To Design And Manufacture A Small Scale Flexible Barrier In Mechanical Similitude With The Prototype Scale.
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Pohl, B., Prince, H., Wille, J., Kingston, D., Cullen, N., & Fauchereau, N. (2023). Atmospheric Rivers And Weather Types In Aotearoa New Zealand: A Two-Way Story. Journal Of Geophysical Research-Atmospheres, 1281(151).
Abstract: Here, We Analyze The Inter-Relationships Between Weather Types (Wts) And Atmospheric Rivers (Ars) Around Aotearoa New Zealand (Anz), Their Respective Properties, As Well As Their Combined And Separate Influence On Daily Precipitation Amounts And Extremes. Results Show That Ars Are Often Associated With 3-4 Wts, But These Wts Change Depending On The Regions Where Ars Landfall. The Wts Most Frequently Associated With Ars Generally Correspond To Those Favoring Anomalously Strong Westerly Wind In The Mid-Latitudes, Especially For Southern Regions Of Anz, Or Northwesterly Anomalies Favoring Moisture Export From The Lower Latitudes, Especially For The Northern Regions. Wts And Ars Show Strong Within-Type And Inter-Event Diversity. The Synoptic Patterns Of The Wts Significantly Differ When They Are Associated With Ar Occurrences, With Atmospheric Centers Of Actions Being Shifted So That Moisture Fluxes Toward Anz Are Enhanced. The Location, Angle, And Persistence Of Ars Appear Strongly Driven By The Synoptic Configurations Of The Wts. Although Total Moisture Transport Shows Weaker Wt-Dependency, It Appears Strongly Related To Zonal Wind Speed To The South Of Anz, Or The Moisture Content Of The Air Mass To The North. Finally, Wt Influence On Daily Precipitation May Completely Change Depending On Their Association, Or Lack Thereof, With Ar Events. Wts Traditionally Considered As Favorable To Wet Conditions May Conceal Daily Precipitation Extremes Occurring During Ar Days, And Anomalously Dry Days Or Near-Climatological Conditions During Non-Ar Days.
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Polton, J., Harle, J., Holt, J., Katavouta, A., Partridge, D., Jardine, J., et al. (2023). Reproducible And Relocatable Regional Ocean Modelling: Fundamentals And Practices. Geoscientific Model Development, 161(5), 1481–1510.
Abstract: In Response To An Increasing Demand For Bespoke Or Tailored Regional Ocean Modelling Configurations, We Outline Fundamental Principles And Practices That Can Expedite The Process To Generate New Configurations. The Paper Develops The Principle Of Reproducibility And Advocates Adherence By Presenting Benefits To The Community And User. The Elements Of This Principle Are Reproducible Workflows And Standardised Assessment, With Additional Effort Over Existing Working Practices Being Balanced Against The Added Value Generated. The Paper Then Decomposes The Complex Build Process, For A New Regional Ocean Configuration, Into Stages And Presents Guidance, Advice And Insight For Each Component. This Advice Is Compiled From Across The Nemo (Nucleus For European Modelling Of The Ocean) User Community And Sets Out Principles And Practises That Encompass Regional Ocean Modelling With Any Model. With Detailed And Region-Specific Worked Examples In Sects. 3 And 4, The Linked Companion Repositories And Dois All Target Nemov4. The Aim Of This Review And Perspective Paper Is To Broaden The User Community Skill Base And To Accelerate Development Of New Configurations In Order To Increase The Time Available For Exploiting The Configurations.
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Rabatel, A., Ducasse, E., Millan, R., & Mouginot, J. (2023). Satellite-Derived Annual Glacier Surface Flow Velocity Products For The European Alps, 2015-2021. Data, .
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Rabatel, A., Ducasse, E., Ramseyer, V., & Millan, R. (2023). State And Fate Of Glaciers In The Val Veny (Mont- Blanc Range, Italy): Contribution Of Optical Satellite Products. Revue De Geographie Alpine-Journal Of Alpine Research, 1111(2).
Abstract: The Glaciers Of The Val Veny (Italian Side Of The Mont-Blanc Massif) Have Been The Site Of Numerous Field Observations During The Last Decades, In Particular For The Study Of Glacial Fluctuations Or Surface Processes Related To The Debris Cover. Here, We Propose To Examine How Satellite Observations Can Complement Field Measurements On The State And Fate Of The Val Veny Glaciers. Indeed, Satellite Products Obtained In A Quasi-Systematic Way Allow To Account Not Only For The Loss Of Surface And Volume, But Also For The Changes In Their Flow Velocities. The Overall Pattern We Document Is A Glacier Thinning And Slowdown Of The Ice Flow, With An Estimated Shrinkage Of 25% By 2050 And A Volume Loss Ranging Between 30 And 43% Depending On The Data Source Used For The Estimation Of The Initial Volume. In Such A Context, A Portion Of The Upper Reaches Of Brenva Glacier Shows An Unexpected Pattern Of Thickening And Increase In Ice Flow That Rises Questions On Its Origin. Finally, The Uncertainties In The Estimation Of Ice Thicknesses Remain Important And Have Repercussions On The Future Evolution Of The Glaciers And Their Contribution From A Hydrological Point Of View. By 2050, We Estimate That The Water Contribution Due To The Volume Loss Of Val Veny Glaciers Could Decrease By 40%.
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Ravanel, L., Duvillard, P., Astrade, L., Faug, T., Deline, P., Berthet, J., et al. (2023). The Taconnaz Rockfall (Mont-Blanc Massif, European Alps) Of November 2018: A Complex And At-Risk Rockwall-Glacier-Torrent Morphodynamic Continuum. Applied Sciences-Basel, 131(171).
Abstract: The Glacial And Torrential Basin Of Taconnaz (Mont-Blanc Massif, France) Dominates The Chamonix Valley. It Is One Of The Major Paths For Snow Avalanches In The Alps, Often Triggered By Serac Falls From The Taconnaz Glacier. On 24 November 2018, The Basin'S Multi-Risk Nature Was Further Accentuated By A New Type Of Hazard With A Rockfall Triggered At C. 2700 M A.S.L. It Travelled Down Over A Distance Of 1.85 Km And Stopped 165 M Away From The Construction Site Of A Micro-Hydroelectric Power Station. We Studied The Triggering Conditions At The Permafrost Lower Limit, The Effects Of The Supra-Glacial Path On The Flow Patterns, And The Fate Of The Scar And The Deposit On Torrential Activity. By Comparing A Pre-Event Structure From Motion Model With A Post-Event Lidar Model, We Estimated The Volume Of The Scar To Be 42,900 M3 (& Plusmn;5%). A Numerical Model Was Employed To Simulate The Rapid Runout. It Revealed The Complexity Of The Flow, Attributed To The Sequestration Of A Part Of The Deposit In Crevasses, The Incorporation Of A Significant Volume Of Ice Resulting In A Transition From A Dry Granular Flow To A Mud-Like Flow, And The Presence Of Numerous Deposit Zones. Subsequent Monitoring Of The Area After The Event Allowed For The Documentation Of The Scar'S Evolution, Including A Landslide, As Well As The Progressive Degradation And Evacuation Of The Deposit By The Torrent Without Producing Debris Flow. The Study Of The Triggering Factors Indicated Glacial Retreat As The Probable Main Cause, Assisted By The Melting Of Ice Lenses Left By The Permafrost Disappearance. Finally, We Present Replicable Methods For Managing Risks At The Site Following The Event. This Event Improves The Understanding Of Cascading Processes That Increasingly Impact Alpine Areas In The Context Of Climate Change.
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Ravanel, L., Guillet, G., Kaushik, S., Preunkert, S., Malet, E., Magnin, F., et al. (2023). Ice Aprons On Steep High-Alpine Slopes: Insights From The Mont-Blanc Massif, Western Alps. Journal Of Glaciology, .
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Recking, A., Tarrio, D., & Piton, G. (2023). The Contribution Of Grain Sorting To The Dynamics Of The Bedload Active Layer. Earth Surface Processes And Landforms, .
Abstract: During The Last 20 Years, Flume And Field Experiments Have Shown That Grain Sorting Contributes To Bed-Level Fluctuations And Bedload Pulses. In This Work, We Propose A New Analysis Of These Experimental Data. From The Flume Data, We Derive A Model For Gravel-Bed Rivers Where Both Local (Bedform-Scale) Slope And Bedload Are Known To Fluctuate Through Space And Time, In The So-Called 'Bedload Active Layer'. The Model Uses Standard Concepts And Empirical Tools With Reach-Averaged Data For The Hydraulics And Sediment Transport. It Considers A Maximum Slope For Local Armouring Equal To The Mean Bed Slope (Reach Scale) Affected By A Coefficient Which Expresses The Difference In Mobility Of The Coarse Fraction Considered Alone Or In A Mixture. The Minimum Local Slope For Bed Erosion Is The Mean Bed Slope Corrected By A Coefficient That Depends On The Armour Ratio A(R) (Ratio Of The Surface To The Subsurface Grain Diameter) And The Reach-Averaged Transport Rate. The Model Is Compared With A Compilation Of Scour-Fill Depths Measured In The Field. Results Suggests That The Slope Fluctuations In 1D Flume Experiments Are Consistent With In-Channel Bed-Level Fluctuations Associated With Scour-Fill Processes In The Active Layer. The Model Also Suggests That Although The Length Scale Of The Maximum Scour Depth Delta Is On The Order Of The Bed Surface D-90, It Is Well Explained By The Product Between The Mean Bed Slope S And The Active Channel Width W, With Delta Approximate To 1.4Sw. For The Pulse Intensity, We Provide A Justification For The Simplified Squared Slope Equation For Solid Concentration C = Q(S)/Q Proportional To S-2 (With Q(S) The Solid Discharge, Q The Water Discharge And S The Slope), Which Has Often Been Used In Place Of Standard Bedload Equations For Modelling Highly Concentrated Bedload Transport Events In Mountain Streams.
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Reese, R., Garbe, J., Hill, E., Urruty, B., Naughten, K., Gagliardini, O., et al. (2023). The Stability Of Present-Day Antarctic Grounding Lines – Part 2: Onset Of Irreversible Retreat Of Amundsen Sea Glaciers Under Current Climate On Centennial Timescales Cannot Be Excluded. Cryosphere, 171(9), 3761–3783.
Abstract: Observations Of Ocean-Driven Grounding-Line Retreat In The Amundsen Sea Embayment In Antarctica Raise The Question Of An Imminent Collapse Of The West Antarctic Ice Sheet. Here We Analyse The Committed Evolution Of Antarctic Grounding Lines Under The Present-Day Climate. To This Aim, We First Calibrate A Sub-Shelf Melt Parameterization, Which Is Derived From An Ocean Box Model, With Observed And Modelled Melt Sensitivities To Ocean Temperature Changes, Making It Suitable For Present-Day Simulations And Future Sea Level Projections. Using The New Calibration, We Run An Ensemble Of Historical Simulations From 1850 To 2015 With A State-Of-The-Art Ice Sheet Model To Create Model Instances Of Possible Present-Day Ice Sheet Configurations. Then, We Extend The Simulations For Another 10 000 Years To Investigate Their Evolution Under Constant Present-Day Climate Forcing And Bathymetry. We Test For Reversibility Of Grounding-Line Movement In The Case That Large-Scale Retreat Occurs. In The Amundsen Sea Embayment We Find Irreversible Retreat Of The Thwaites Glacier For All Our Parameter Combinations And Irreversible Retreat Of The Pine Island Glacier For Some Admissible Parameter Combinations. Importantly, An Irreversible Collapse In The Amundsen Sea Embayment Sector Is Initiated At The Earliest Between 300 And 500 Years In Our Simulations And Is Not Inevitable Yet – As Also Shown In Our Companion Paper Part 1,. In Other Words, The Region Has Not Tipped Yet. With The Assumption Of Constant Present-Day Climate, The Collapse Evolves On Millennial Timescales, With A Maximum Rate Of 0.9 Mma-1 Sea-Level-Equivalent Ice Volume Loss. The Contribution To Sea Level By 2300 Is Limited To 8 Cm With A Maximum Rate Of 0.4 Mma-1 Sea-Level-Equivalent Ice Volume Loss. Furthermore, When Allowing Ice Shelves To Regrow To Their Present Geometry, We Find That Large-Scale Grounding-Line Retreat Into Marine Basins Upstream Of The Filchner-Ronne Ice Shelf And The Western Siple Coast Is Reversible. Other Grounding Lines Remain Close To Their Current Positions In All Configurations Under Present-Day Climate.
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Reuter, B., Hagenmuller, P., & Eckert, N. (2023). Snow And Avalanche Climates In The French Alps Using Avalanche Problem Frequencies. Journal Of Glaciology, .
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Robledano, A., Picard, G., Dumont, M., Flin, F., Arnaud, L., & Libois, Q. (2023). Unraveling The Optical Shape Of Snow. Nature Communications, 141(1).
Abstract: The Reflection Of Sunlight Off The Snow Is A Major Driver Of The Earth'S Climate. This Reflection Is Governed By The Shape And Arrangement Of Ice Crystals At The Micrometer Scale, Called Snow Microstructure. However, Snow Optical Models Overlook The Complexity Of This Microstructure By Using Simple Shapes, And Mainly Spheres. The Use Of These Various Shapes Leads To Large Uncertainties In Climate Modeling, Which Could Reach 1.2 K In Global Air Temperature. Here, We Accurately Simulate Light Propagation In Three-Dimensional Images Of Natural Snow At The Micrometer Scale, Revealing The Optical Shape Of Snow. This Optical Shape Is Neither Spherical Nor Close To The Other Idealized Shapes Commonly Used In Models. Instead, It More Closely Approximates A Collection Of Convex Particles Without Symmetry. Besides Providing A More Realistic Representation Of Snow In The Visible And Near-Infrared Spectral Region (400 To 1400 Nm), This Breakthrough Can Be Directly Used In Climate Models, Reducing By 3 The Uncertainties In Global Air Temperature Related To The Optical Shape Of Snow. Micrometre Scale Simulation Of The Trajectory Of Sunlight As It Reaches The Snowpack Shows What Snow Looks Like From The Photon'S Perspective, Providing A More Universal Representation Of Snow In Optical Models.
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Ruiz-Villanueva, V., Piégay, H., Scorpio, V., Bachmann, A., Brousse, G., Cavalli, M., et al. (2023). River Widening In Mountain And Foothill Areas During Floods: Insights From A Meta-Analysis Of 51 European Rivers. Science Of The Total Environment, 9039.
Abstract: River Widening, Defined As A Lateral Expansion Of The Channel, Is A Critical Process That Maintains Fluvial Ecosystems And Is Part Of The Regular Functioning Of Rivers. However, In Areas With High Population Density, Channel Widening Can Cause Damage During Floods. Therefore, For Effective Flood Risk Management It Is Essential To Identify River Reaches Where Abrupt Channel Widening May Occur. Despite Numerous Efforts To Predict Channel Widening, Most Studies Have Been Limited To Single Rivers And Single Flood Events, Which May Not Be Representative Of Other Conditions. Moreover, A Multi-Catchment Scale Approach That Covers Various Settings And Flood Magnitudes Has Been Lacking. In This Study, We Fill This Gap By Compiling A Large Database Comprising 1564 River Reaches In Several Mountain Regions In Europe Affected By Floods Of Varying Magnitudes In The Last Six Decades. By Applying A Meta-Analysis, We Aimed To Identify The Types Of Floods Responsible For More Extensive Widening, The River Reach Types Where Intense Widening Is More Likely To Occur, And The Hydraulic And Morphological Variables That Explain Widening And Can Aid In Predicting Widening. Our Analysis Revealed Seven Groups Of Reaches With Significantly Different Responses To Floods Regarding Width Ratios (I.E., The Ratio Between Channel Width After And Before A Flood). Among These Groups, The River Reaches Located In The Mediterranean Region And Affected By Extreme Floods Triggered By Short And Intense Precipitation Events Showed Significantly Larger Widening Than Other River Reaches In Other Regions. Additionally, The Meta-Analysis Confirmed Valley Confinement As A Critical Morphological Variable That Controls Channel Widening But Showed That It Is Not The Only Controlling Factor. We Proposed New Statistical Models To Identify River Reaches Prone To Widening, Estimate Potential Channel Width After A Flood, And Compute Upper Bound Width Ratios. These Findings Can Inform Flood Hazard Evaluations And The Design Of Mitigation Measures.
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Ruyer-Quil, C., Bresch, D., Gisclon, M., Richard, G., Kessar, M., & Cellier, N. (2023). Sliding And Merging Of Strongly Sheared Droplets. Journal Of Fluid Mechanics, 9729.
Abstract: A Mathematical And Numerical Framework Is Proposed To Compute The Displacement And Merging Dynamics Of Sliding Droplets Under The Action Of A Constant Shear Exerted By A Gas Flow. An Augmented Formulation Is Implemented To Model Surface Tension Including The Full Curvature Of The Free Surface. A Set Of Shallow-Water Evolution Equations Is Obtained For The Film Thickness, The Averaged Velocity, An Additional Quantity (With Dimension Of A Velocity) Taking Into Account The Capillary Effects And A Tensor Called Enstrophy. The Enstrophy Accounts For The Deviation Of The Velocity Profile From A Constant Velocity Distribution. The Formulation Is Consistent With The Long-Wave Expansion Of The Basic Equations With A Conservative Part And Source Terms Including The Effect Of Viscosity, In The Form Of A Viscous Friction And The Effect Of The Shear Stress. The Model Is Hyperbolic With Generalised Diffusion Terms Due To Capillarity. Finally, Our Model Is Completed With A Disjoining Pressure Formulation That Is Able To Account For The Hysteresis Of The Static Contact Angle. In This Formulation, The Advancing Or Receding Nature Of The Contact Line Is Assessed By The Accumulation Or Reduction Of Mass Of The Droplet At The Contact Line. Simulations Of Sliding Water Droplets Are Performed With Periodic Boundary Conditions In A Domain Of Limited Size. Hysteresis Of The Static Contact Angle Causes A Slowdown Of The Drops And A Delay In The Sequence Of Coalescence Of The Drops.
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Schaafsma, M., Ahn, S., Castro, A., Dendoncker, N., Filyushkina, A., González-Jiménez, D., et al. (2023). Whose Values Count? A Review Of The Nature Valuation Studies With A Focus On Justice. Current Opinion In Environmental Sustainability, 646.
Abstract: The Values Assessment Of The Intergovernmental Science -Policy Platform On Biodiversity And Ecosystem Services Shows That Multiple Valuation Methods And Approaches Exist To Assess Diverse Value Types. The Evidence Is Based On The Largest Review Of Academic Valuation Studies On Nature To Date, Developed For The Values Assessment Of The Intergovernmental Science-Policy Platform On Biodiversity And Ecosystem Services (Ipbes). We Evaluate Studies According To Environmental Justice Criteria. The Results Suggest That Although Diverse Value Types And Indicators Are Assessed Across Studies, Few Individual Studies Are Plural, And Studies Fail To Provide Evidence On Distributive Justice And Score Low On Procedural Justice Indicators. We Provide A Set Of Recommendations For Incorporating Issues Of Justice In The Design Of Valuation Studies.
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Sedakov, R., Osadchiev, A., Barnier, B., Molines, J., & Colombo, P. (2023). Large Chocked Lagoon As A Barrier For River-Sea Flux Of Dissolved Pollutants: Case Study Of The Azov Sea And The Black Sea. Marine Pollution Bulletin, 1871.
Abstract: The Don River Is Among The Largest Rivers In The Eastern Europe And Is Heavily Polluted. This River Inflows Into Small And Semi-Isolated Sea Of Azov, Which Is Connected With The Black Sea By A Narrow Strait. Generally, The Sea Of Azov Is A Large Choked Lagoon, Which Serves As A Barrier For River-Borne Constituents. Using Numerical Modeling, We Reveal That Presence Of The Choked Lagoon Significantly Slows Down The Estuary-Seawater Flux Of Dissolved Pollutants And Slackens Its Discharge-Induced Seasonal Variability. In Particular, The Sea Of Azov Delays The 5 % And 95 % Of The Total Flux Of Riverine Pollution To The Black Sea By 9 And 36 Months, Respectively. The Obtained Results Are Important For Assessment The Influence Of Background And Emergency Pollution Accidents At The Don River On Water Quality In The Study Region. Moreover, These Results Could Be Applied To Many Other Chocked Lagoons In The World Ocean.
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Seroussi, H., Verjans, V., Nowicki, S., Payne, A., Goelzer, H., Lipscomb, W., et al. (2023). Insights Into The Vulnerability Of Antarctic Glaciers From The Ismip6 Ice Sheet Model Ensemble And Associated Uncertainty. Cryosphere, 171(121), 5197–5217.
Abstract: The Antarctic Ice Sheet Represents The Largest Source Of Uncertainty In Future Sea Level Rise Projections, With A Contribution To Sea Level By 2100 Ranging From – 5 To 43 Cm Of Sea Level Equivalent Under High Carbon Emission Scenarios Estimated By The Recent Ice Sheet Model Intercomparison For Cmip6 (Ismip6). Ismip6 Highlighted The Different Behaviors Of The East And West Antarctic Ice Sheets, As Well As The Possible Role Of Increased Surface Mass Balance In Offsetting The Dynamic Ice Loss In Response To Changing Oceanic Conditions In Ice Shelf Cavities. However, The Detailed Contribution Of Individual Glaciers, As Well As The Partitioning Of Uncertainty Associated With This Ensemble, Have Not Yet Been Investigated. Here, We Analyze The Ismip6 Results For High Carbon Emission Scenarios, Focusing On Key Glaciers Around The Antarctic Ice Sheet, And We Quantify Their Projected Dynamic Mass Loss, Defined Here As Mass Loss Through Increased Ice Discharge Into The Ocean In Response To Changing Oceanic Conditions. We Highlight Glaciers Contributing The Most To Sea Level Rise, As Well As Their Vulnerability To Changes In Oceanic Conditions. We Then Investigate The Different Sources Of Uncertainty And Their Relative Role In Projections, For The Entire Continent And For Key Individual Glaciers. We Show That, In Addition To Thwaites And Pine Island Glaciers In West Antarctica, Totten And Moscow University Glaciers In East Antarctica Present Comparable Future Dynamic Mass Loss And High Sensitivity To Ice Shelf Basal Melt. The Overall Uncertainty In Additional Dynamic Mass Loss In Response To Changing Oceanic Conditions, Compared To A Scenario With Constant Oceanic Conditions, Is Dominated By The Choice Of Ice Sheet Model, Accounting For 52 % Of The Total Uncertainty Of The Antarctic Dynamic Mass Loss In 2100. Its Relative Role For The Most Dynamic Glaciers Varies Between 14 % For Macayeal And Whillans Ice Streams And 56 % For Pine Island Glacier At The End Of The Century. The Uncertainty Associated With The Choice Of Climate Model Increases Over Time And Reaches 13 % Of The Uncertainty By 2100 For The Antarctic Ice Sheet But Varies Between 4 % For Thwaites Glacier And 53 % For Whillans Ice Stream. The Uncertainty Associated With The Ice-Climate Interaction, Which Captures Different Treatments Of Oceanic Forcings Such As The Choice Of Melt Parameterization, Its Calibration, And Simulated Ice Shelf Geometries, Accounts For 22 % Of The Uncertainty At The Ice Sheet Scale But Reaches 36 % And 39 % For Institute Ice Stream And Thwaites Glacier, Respectively, By 2100. Overall, This Study Helps Inform Future Research By Highlighting The Sectors Of The Ice Sheet Most Vulnerable To Oceanic Warming Over The 21St Century And By Quantifying The Main Sources Of Uncertainty.
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Servettaz, A., Agosta, C., Kittel, C., & Orsi, A. (2023). Control Of The Temperature Signal In Antarctic Proxies By Snowfall Dynamics. Cryosphere, 171(121), 5373–5389.
Abstract: Antarctica, The Coldest And Driest Continent, Is Home To The Largest Ice Sheet, Whose Mass Is Predominantly Recharged By Snowfall. A Common Feature Of Polar Regions Is The Warming Associated With Snowfall, As Moist Oceanic Air And Cloud Cover Increase The Surface Temperature. Consequently, Snow That Accumulates On The Ice Sheet Is Deposited Under Unusually Warm Conditions. Here We Use A Polar-Oriented Regional Atmospheric Model To Study The Statistical Difference Between Average And Snowfall-Weighted Temperatures. During Snowfall, The Warm Anomaly Scales With Snowfall Amount, With The Strongest Sensitivity Occurring At Low-Accumulation Sites. Heavier Snowfall In Winter Helps To Decrease The Annual Snowfall-Weighted Temperature, But This Effect Is Overwritten By The Event-Scale Warming Associated With Precipitating Atmospheric Systems, Which Particularly Contrast With The Extremely Cold Conditions That Occur In Winter. Consequently, The Seasonal Range Of Snowfall-Weighted Temperature Is Reduced By 20 %. On The Other Hand, The Annual Snowfall-Weighted Temperature Shows 80 % More Interannual Variability Than The Annual Temperature Due To The Irregularity Of Snowfall Occurrence And Its Associated Temperature Anomaly. Disturbances Of The Apparent Annual Temperature Cycle And Interannual Variability Have Important Consequences For The Interpretation Of Water Isotopes In Precipitation, Which Are Deposited With Snowfall And Commonly Used For Paleotemperature Reconstructions From Ice Cores.
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Servettaz, A., Orsi, A., Curran, M., Moy, A., Landais, A., Mcconnell, J., et al. (2023). A 2000-Year Temperature Reconstruction On The East Antarctic Plateau From Argon-Nitrogen And Water Stable Isotopes In The Aurora Basin North Ice Core. Climate Of The Past, , 112511–115211.
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Sherpa, T., Matthews, T., Perry, L., Thapa, A., Singh, P., Khadka, A., et al. (2023). Insights From The First Winter Weather Observations Near Mount Everest'S Summit. Weather, .
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Sherpa, T., Matthews, T., Perry, L., Thapa, A., Singh, P., Khadka, A., et al. (2023). Insights From The First Winter Weather Observations Near Mount Everest'S Summit. Weather, 787(121), 344–348.
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Sicart, J., Ramseyer, V., Picard, G., Arnaud, L., Coulaud, C., Freche, G., et al. (2023). Snow Accumulation And Ablation Measurements In A Midlatitude Mountain Coniferous Forest (Col De Porte, France, 1325 M Altitude): The Snow Under Forest (Snouf) Field Campaign Data Set. Earth System Science Data, 151(111), 5121–5133.
Abstract: Forests Strongly Modify The Accumulation, Metamorphism And Melting Of Snow In Midlatitude And High-Latitude Regions. Recently, Snow Routines In Hydrological And Land Surface Models Were Improved To Incorporate More Accurate Representations Of Forest Snow Processes, But Model Intercomparison Projects Have Identified Deficiencies, Partly Due To Incomplete Knowledge Of The Processes Controlling Snow Cover In Forests. The Snow Under Forest (Snouf) Project Was Initiated To Enhance Knowledge Of The Complex Interactions Between Snow And Vegetation. Two Field Campaigns, During The Winters 2016-2017 And 2017-2018, Were Conducted In A Coniferous Forest Bordering The Snow Study At Col De Porte (1325 M A.S.L., French Alps) To Document The Snow Accumulation And Ablation Processes. This Paper Presents The Field Site, The Instrumentation And The Collection And Postprocessing Methods. The Observations Include Distributed Forest Characteristics (Tree Inventory, Lidar Measurements Of Forest Structure, Subcanopy Hemispherical Photographs), Meteorology (Automatic Weather Station And An Array Of Radiometers), Snow Cover And Depth (Snow Pole Transect And Laser Scan) And Snow Interception By The Canopy During Precipitation Events. The Weather Station Installed Under Dense Canopy During The First Campaign Has Been Maintained Since Then And Has Provided Continuous Measurements Throughout The Year Since 2018. Data Are Publicly Available From The Repository Of The Observatoire Des Sciences De L'Univers De Grenoble (Osug) Data Center At 10.17178/Snouf.2022 (Sicart Et Al., 2022).
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Sierra, J., Espinoza, J., Junquas, C., Wongchuig, S., Polcher, J., Moron, V., et al. (2023). Impacts Of Land-Surface Heterogeneities And Amazonian Deforestation On The Wet Season Onset In Southern Amazon. Climate Dynamics, .
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Smith, M., Angot, H., Chamberlain, E., Droste, E., Karam, S., Muilwijk, M., et al. (2023). Thin And Transient Meltwater Layers And False Bottoms In The Arctic Sea Ice Pack-Recent Insights On These Historically Overlooked Features. Elementa-Science Of The Anthropocene, 111(1).
Abstract: The Rapid Melt Of Snow And Sea Ice During The Arctic Summer Provides A Significant Source Of Low-Salinity Meltwater To The Surface Ocean On The Local Scale. The Accumulation Of This Meltwater On, Under, And Around Sea Ice Floes Can Result In Relatively Thin Meltwater Layers In The Upper Ocean. Due To The Small-Scale Nature Of These Upper-Ocean Features, Typically On The Order Of 1 M Thick Or Less, They Are Rarely Detected By Standard Methods, But Are Nevertheless Pervasive And Critically Important In Arctic Summer. Observations During The Multidisciplinary Drifting Observatory For The Study Of Arctic Climate (Mosaic) Expedition In Summer 2020 Focused On The Evolution Of Such Layers And Made Significant Advancements In Understanding Their Role In The Coupled Arctic System. Here We Provide A Review Of Thin Meltwater Layers In The Arctic, With Emphasis On The New Findings From Mosaic. Both Prior And Recent Observational Datasets Indicate An Intermittent Yet Long-Lasting (Weeks To Months) Meltwater Layer In The Upper Ocean On The Order Of 0.1 M To 1.0 M In Thickness, With A Large Spatial Range. The Presence Of Meltwater Layers Impacts The Physical System By Reducing Bottom Ice Melt And Allowing New Ice Formation Via False Bottom Growth. Collectively, The Meltwater Layer And False Bottoms Reduce Atmosphere-Ocean Exchanges Of Momentum, Energy, And Material. The Impacts On The Coupled Arctic System Are Far-Reaching, Including Acting As A Barrier For Nutrient And Gas Exchange And Impacting Ecosystem Diversity And Productivity.
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Sonke, J., Angot, H., Zhang, Y., Poulain, A., Bjorn, E., & Schartup, A. (2023). Global Change Effects On Biogeochemical Mercury Cycling. Ambio, .
Abstract: Past And Present Anthropogenic Mercury (Hg) Release To Ecosystems Causes Neurotoxicity And Cardiovascular Disease In Humans With An Estimated Economic Cost Of $117 Billion Usd Annually. Humans Are Primarily Exposed To Hg Via The Consumption Of Contaminated Freshwater And Marine Fish. The Unep Minamata Convention On Hg Aims To Curb Hg Release To The Environment And Is Accompanied By Global Hg Monitoring Efforts To Track Its Success. The Biogeochemical Hg Cycle Is A Complex Cascade Of Release, Dispersal, Transformation And Bio-Uptake Processes That Link Hg Sources To Hg Exposure. Global Change Interacts With The Hg Cycle By Impacting The Physical, Biogeochemical And Ecological Factors That Control These Processes. In This Review We Examine How Global Change Such As Biome Shifts, Deforestation, Permafrost Thaw Or Ocean Stratification Will Alter Hg Cycling And Exposure. Based On Past Declines In Hg Release And Environmental Levels, We Expect That Future Policy Impacts Should Be Distinguishable From Global Change Effects At The Regional And Global Scales.
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Spiric, J., Salinas-Melgoza, M., Merlo-Reyes, A., & Ramirez, M. (2023). Estimating The Causal Effect Of Forestry Programs On Forest Recovery In A Redd Plus Priority Area In Michoac?An, Mexico. Forest Policy And Economics, 1461.
Abstract: We Evaluated The Causal Effect Of The Forestry Programs Implemented From 2007 To 2018 On The Forest Recovery In The Municipality Of Zit ' Acuaro In Central Mexico, Part Of The Cutzamala Region, A Redd+ Priority Implementation Area. We Produced Detailed Land Use/Land Cover (Lulc) Maps To Measure Forest Loss And Recovery In The Study Period At The Municipal Level. To Evaluate The Effect Of Active Forest Recovery We Used A Quasi-Experimental Design To Compare Forest Cover Change Between Agrarian Nuclei With And Without Forestry Programs. Although Defor-Estation Was The Most Dominant Forest Cover Change Process In 2007-2018 In Zit ' Acuaro, Forest Recovery, Mostly In The Form Of Forest Densification, Occurred In Areas Of Comparable Size. However, The Causal Effect Of Forestry Programs On Forest Cover And Density Increase At The Agrarian Nuclei Level Was Negligible. The Passive Forest Regrowth Resulting From Agricultural Abandonment Or Postfire Regeneration Could Have Been More Determinant Of Forest Recovery In The Study Period. Detailed Qualitative Local Data Will Be Needed To Understand Factors And Reasons For Passive Recovery To Support This Process In The Future.
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Strohmenger, L., Sauquet, E., Bernard, C., Bonneau, J., Branger, F., Bresson, A., et al. (2023). On The Visual Detection Of Non-Natural Records In Streamflow Time Series: Challenges And Impacts. Hydrology And Earth System Sciences, 272(181), 3375–3391.
Abstract: Large Datasets Of Long-Term Streamflow Measurements Are Widely Used To Infer And Model Hydrological Processes. However, Streamflow Measurements May Suffer From What Users Can Consider Anomalies, I.E. Non-Natural Records That May Be Erroneous Streamflow Values Or Anthropogenic Influences That Can Lead To Misinterpretation Of Actual Hydrological Processes. Since Identifying Anomalies Is Time Consuming For Humans, No Study Has Investigated Their Proportion, Temporal Distribution, And Influence On Hydrological Indicators Over Large Datasets. This Study Summarizes The Results Of A Large Visual Inspection Campaign Of 674 Streamflow Time Series In France Made By 43 Evaluators, Who Were Asked To Identify Anomalies Falling Under Five Categories, Namely, Linear Interpolation, Drops, Noise, Point Anomalies, And Other. We Examined The Evaluators' Individual Behaviour In Terms Of Severity And Agreement With Other Evaluators, As Well As The Temporal Distributions Of The Anomalies And Their Influence On Commonly Used Hydrological Indicators. We Found That Inter-Evaluator Agreement Was Surprisingly Low, With An Average Of 12 % Of Overlapping Periods Reported As Anomalies. These Anomalies Were Mostly Identified As Linear Interpolation And Noise, And They Were More Frequently Reported During The Low-Flow Periods In Summer. The Impact Of Cleaning Data From The Identified Anomaly Values Was Higher On Low-Flow Indicators Than On High-Flow Indicators, With Change Rates Lower Than 5 % Most Of The Time. We Conclude That The Identification Of Anomalies In Streamflow Time Series Is Highly Dependent On The Aims And Skills Of Each Evaluator, Which Raises Questions About The Best Practices To Adopt For Data Cleaning.
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Sutherland, I., Van Vianen, J., Rowland, D., Palomo, I., Pascual, U., Mathys, A., et al. (2023). Use, Value, And Desire: Ecosystem Services Under Agricultural Intensification In A Changing Landscape In West Kalimantan (Indonesia). Regional Environmental Change, 232(4).
Abstract: A Fundamental Challenge Is To Understand And Navigate Trade-Offs Between Ecosystem Services (Es) In Dynamic Landscapes And To Account For Interactions Between Local People And Broad-Scale Drivers, Such As Agricultural Intensification. Many Analyses Of Es Trade-Offs Rely On Static Mapping And Biophysical Indicators While Disregarding The Multiple Uses, Values, And Desires For Es (Uvd-Es) That Local People Associate With Their Changing Landscapes. Here, A Participatory Uvd-Es Framework Was Applied To Assess Differences In The Use, Values, And Desire Of Es Between Three Zones With Different Land-Use Intensities (With Pre-Frontier, Frontier, And Post-Frontier Landscapes) In West Kalimantan (Indonesia). The Analysis Revealed That (1) Almost The Full Suite Of Es Uses Has Become Destabilized As A Result Of Agricultural Intensification; (2) Es More Closely Associated With Agricultural Intensification Were Largely Desired By Local People Yet They Still Valued A Diversity Of Traditional Es, Such As Those Derived From The Provision Of Non-Timber Forest Products, Fish, And Other Es Associated With Non-Material Aspects Including Those Tied To Traditional Culture; (3) The Mismatch In Used Es Versus Valued Es Increased With Agricultural Intensification Due To A Decrease In The Flow Of Non-Timber Forest Products, Aquatic, Regulating, And Non-Material (Cultural) Es. Together, Exploring Uvd-Es Patterns In A Participatory Way Helped To Reveal Locally Relevant Social-Ecological Drivers Of Es And A Multidimensional Perspective Of Es Trade-Offs. Our Uvd-Es Framework Offers An Opportunity To Foster Participation As A Way To Reconnect Global Environmental Research Agendas With Local And Regional Landscape Contexts.
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T Veld, M., Pandolfi, M., Amato, F., Perez, N., Reche, C., Dominutti, P., et al. (2023). Discovering Oxidative Potential (Op) Drivers Of Atmospheric Pm10, Pm2.5, And Pm1 Simultaneously In North-Eastern Spain. Science Of The Total Environment, 8578.
Abstract: Ambient Particulate Matter (Pm) Is A Major Contributor To Air Pollution, Leading To Adverse Health Effects On The Human Population. It Has Been Suggested That The Oxidative Potential (Op, As A Tracer Of Oxidative Stress) Of Pm Is A Possible Determinant Of Its Health Impact. In This Study, Samples Of Pm10, Pm2.5, And Pm1 Were Collected Roughly Every Four Days From January 2018 Until March 2019 At A Barcelona Urban Background Site And Montseny Rural Background Site In Northeastern Spain. We Determined The Chemical Composition Of Samples, Allowing Us To Perform Source Apportionment Using Positive Matrix Factorization. The Op Of Pm Was Determined By Measuring Reactive Oxygen Species Using Dithiothreitol And Ascorbic Acid Assays. Finally, To Link The Sources With The Measured Op, Both A Pearson'S Correlation And A Multiple Linear Regression Model Were Applied To The Dataset. The Results Showed That In Barcelona, The Op Of Pm10 Was Much Higher Than Those Of Pm2.5 And Pm1, Whereas In Montseny Results For All Pm Sizes Were In The Same Range, But Significantly Lower Than In Barcelona. In Barcelona, Several Anthropogenic Sources Were The Main Drivers Of Op In Pm10 (Combustion + Road Dust + Heavy Oil + Oc-Rich) And Pm2.5 (Road Dust + Combustion). In Contrast, Pm1 -Associated Op Was Driven By Industry, With A Much Lower Contribution To Pm10 And Pm2.5 Mass. Meanwhile, Montseny Exhibited No Clear Drivers For Op Evolution, Likely Explaining The Lack Of A Significant Difference In Op Between Pm10, Pm2.5, And Pm1. Overall, This Study Indicates That Size Fraction Matters For Op, As A Function Of The Environment Typology. In An Urban Context, Op Is Driven By The Pm10 And Pm1 Size Fractions, Whereas Only The Pm1 Fraction Is Involved In Rural Environments.
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Tall, M., Sylla, M., Dajuma, A., Almazroui, M., Houteta, D., Klutse, N., et al. (2023). Drought Variability, Changes And Hot Spots Across The African Continent During The Historical Period (1928-2017). International Journal Of Climatology, .
Abstract: The Spatiotemporal Variability Of Meteorological Droughts, Its Changes And Hot Spots Location Across Africa Are Analysed For The Period Spanning 1928-2017 Using The Standardized Precipitation Index (Spi) Applied To The Precipitation Products From The Climatic Research Unit (Cru), University Of Delaware (Udel) And Global Precipitation Climatology Centre (Gpcc). Spatially, An Analysis Based On Rotational Empirical Orthogonal Function Identifies Five Regions Of Similar Drought Variability, Namely The Sahel, East Africa, East Southern Africa, West Southern Africa And The Gulf Of Guinea. Temporally, The Most Common Periods Of Drought Occurrence Are The 1970S, The 1980S And, To A Lesser Extent, The 1990S. Changes In Drought Characteristics For The Intermediate Past (1958-1987) And Recent Past (1988-2017) Compared To The Far Past (1928-1957) Indicate Robust Increases Of Drought Duration, Frequency And Severity In The Sahel, And To A Lower Extent In The Gulf Of Guinea, Some Areas Of Central Africa, Part Of Southern Africa And Over Madagascar. These Changes Are Stronger (Weaker) Along The Sahel During The Intermediate Past (Recent Past) And Stronger (Weaker) Over Central And Southern Africa And Madagascar During The Recent Past (Intermediate Past). As A Consequence, Drought Hot Spots, Mostly Driven By Severity During The Regions' Wet Season, Are Identified In Areas Confined In The Sahel During The Intermediate Past And In Regions Mainly Over Central And Southern Africa And Madagascar During The Recent Past. Our Results Are Useful For Drought Disaster Risk Management Across Africa And Provide A Valuable Reference For Future Drought Analysis Under Global Warming Conditions.
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Tang, S., Vlug, A., Piao, S., Li, F., Wang, T., Krinner, G., et al. (2023). Regional And Tele-Connected Impacts Of The Tibetan Plateau Surface Darkening. Nature Communications, 141(1).
Abstract: Despite Knowledge Of The Presence Of The Tibetan Plateau (Tp) In Reorganizing Large-Scale Atmospheric Circulation, It Remains Unclear How Surface Albedo Darkening Over Tp Will Impact Local Glaciers And Remote Asian Monsoon Systems. Here, We Use A Coupled Land-Atmosphere Global Climate Model And A Glacier Model To Address These Questions. Under A High-Emission Scenario, Tp Surface Albedo Darkening Will Increase Local Temperature By 0.24 K By The End Of This Century. This Warming Will Strengthen The Elevated Heat Pump Of Tp, Increasing South Asian Monsoon Precipitation While Exacerbating The Current “South Flood-North Drought” Pattern Over East Asia. The Albedo Darkening-Induced Climate Change Also Leads To An Accompanying Tp Glacier Volume Loss Of 6.9%, Which Further Increases To 25.2% At The Equilibrium, With A Notable Loss In Western Tp. Our Findings Emphasize The Importance Of Land-Surface Change Responses In Projecting Future Water Resource Availability, With Important Implications For Water Management Policies. Impacts Of Tibetan Plateau Darkening Remain Unclear. Here Authors Show That Darkening Under The Rcp8.5 Scenario Will Increase South Asian Monsoon Precipitation And The “South Flood-North Drought” Pattern Over East Asia, While Lead To Local Glacier Loss.
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Tassone, A., Magand, O., Naccarato, A., Martino, M., Amico, D., Sprovieri, F., et al. (2023). Seven-Year Monitoring Of Mercury In Wet Precipitation And Atmosphere At The Amsterdam Island Gmos Station. Heliyon, 9(3).
Abstract: Mercury (Hg) Fate And Transport Research Requires More Effort To Obtain A Deep Knowledge Of Its Biogeochemical Cycle, Particularly In The Southern Hemisphere And Tropics That Are Still Missing Of Distributed Monitoring Sites.Continuous Monitoring Of Atmospheric Hg Concentrations And Trend Worldwide Is Relevant For The Effectiveness Evaluation Of The Minamata Convention On Mercury (Mcm) Actions. In This Context, Gaseous Elemental Mercury (Gem) And Total Mercury (Thg) In Precipitations Were Monitored From 2013 To 2019 At The Amsterdam Island Observatory (Ams -37 Degrees 48 ' S, 77 Degrees 34 ' E) To Provide Insights Into The Hg Pathway In The Remote Southern Indian Ocean, Also Considering Ancillary Dataset Of Rn-222, Co2, Co, And Ch4. Gem Average Concentration Was 1.06 +/- 0.07 Ng M- 3, With A Slight Increase During The Austral Winter Due To Both Higher Wind Speed Over The Surface Ocean And Contributions From Southern Africa. In Wet Depositions, Thg Average Concen-Tration Was 2.39 +/- 1.17 Ng L-1, Whereas The Annual Flux Averaged 2.04 +/- 0.80 Mu Gm- 2 Year -1. In General, Both Gem And Volume-Weighted Mean Concentration (Vwmc) Of Thg Did Not Show An Increasing/Decreasing Trend Over The Seven-Year Period, Suggesting A Substantial Lack Of Evolution About Emission Of Hg Reaching Ams.Air Masses Cluster Analysis And Potential Source Contribution Function Showed That Oceanic Evasion Was The Main Hg Contributor At Ams, While Further Contributions Were Attributable To Long-Range Transport Events From Southern Africa, Particularly When The Occurrence Of El Nin Similar To O Increased The Frequency Of Wildfires.
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Tebaldi, C., Adalgeirsdottir, G., Drijfhout, S., Dunne, J., Edwards, T., Fischer, E., et al. (2023). The Hazard Components Of Representative Key Risks. The Physical Climate Perspective. Climate Risk Management, .
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Termansen, M., Jacobs, S., Pandit, R., Mwampamba, T., Dendoncker, N., Schaafsma, M., et al. (2023). Five Steps Towards Transformative Valuation Of Nature. Current Opinion In Environmental Sustainability, 646.
Abstract: The Values Assessment (Va) Of The Intergovernmental Science Policy Platform On Biodiversity And Ecosystem Services Shows That While A Wide Range Of Valuation Methods Exist To Include Nature'S Values In Diverse Decision-Making Contexts, Uptake Of These Methods Remains Limited. Building On The Va, This Paper Reviews Five Critical Steps In The Evaluation Of Project Or Policy Proposals That Can Improve The Inclusion Of Nature'S Values In Decisions. Furthermore, Improving Valuation Practice Requires Guidelines That Utilise Quality Criteria For Valuation Of Nature And Ensure A Balance Between Them. This Paper Proposes Three Such Quality Criteria: Relevance, Robustness And Resource Efficiency. The Paper Argues That The Five Steps And Three Rs Can Generate A Practical Checklist To Support Commissioning, Evaluation And Performance Of More Plural Valuations. Such Guidelines Can Provide The Next Steps Needed To Improve Uptake Of Nature Valuation In Decision-Making.
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Tham, Y., Sarnela, N., Iyer, S., Li, Q., Angot, H., Quelever, L., et al. (2023). Widespread Detection Of Chlorine Oxyacids In The Arctic Atmosphere. Nature Communications, 141(1).
Abstract: Observations Are Reported Of Hclo3 And Hclo4 In The Atmosphere And Their Widespread Occurrence Over The Pan-Arctic During Spring, Providing Further Insights Into Atmospheric Chlorine Cycling In The Polar Environment. Chlorine Radicals Are Strong Atmospheric Oxidants Known To Play An Important Role In The Depletion Of Surface Ozone And The Degradation Of Methane In The Arctic Troposphere. Initial Oxidation Processes Of Chlorine Produce Chlorine Oxides, And It Has Been Speculated That The Final Oxidation Steps Lead To The Formation Of Chloric (Hclo3) And Perchloric (Hclo4) Acids, Although These Two Species Have Not Been Detected In The Atmosphere. Here, We Present Atmospheric Observations Of Gas-Phase Hclo3 And Hclo4. Significant Levels Of Hclo3 Were Observed During Springtime At Greenland (Villum Research Station), Ny-Angstrom Lesund Research Station And Over The Central Arctic Ocean, On-Board Research Vessel Polarstern During The Multidisciplinary Drifting Observatory For The Study Of The Arctic Climate (Mosaic) Campaign, With Estimated Concentrations Up To 7 X 10(6) Molecule Cm(-3). The Increase In Hclo3, Concomitantly With That In Hclo4, Was Linked To The Increase In Bromine Levels. These Observations Indicated That Bromine Chemistry Enhances The Formation Of Oclo, Which Is Subsequently Oxidized Into Hclo3 And Hclo4 By Hydroxyl Radicals. Hclo3 And Hclo4 Are Not Photoactive And Therefore Their Loss Through Heterogeneous Uptake On Aerosol And Snow Surfaces Can Function As A Previously Missing Atmospheric Sink For Reactive Chlorine, Thereby Reducing The Chlorine-Driven Oxidation Capacity In The Arctic Boundary Layer. Our Study Reveals Additional Chlorine Species In The Atmosphere, Providing Further Insights Into Atmospheric Chlorine Cycling In The Polar Environment.
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Thiria, S., Sorror, C., Archambault, T., Charantonis, A., Bereziat, D., Mejia, C., et al. (2023). Downscaling Of Ocean Fields By Fusion Of Heterogeneous Observations Using Deep Learning Algorithms. Ocean Modelling, 1821.
Abstract: We Present A Deep Learning Method To Downscale Low-Resolution Geophysical Fields By Merging Them With High-Resolution Data. The Downscaling Was Performed Using An Ensemble Of Convolutional Neural Networks (Cnns), Whose Prediction Values Are The Average Values Of The Outputs Of 20 Cnns. Academic Experiments Were Conducted On Simulated Ocean Data In The Gulf Stream Region, Given By The Outputs Of The Natl60 Model. The Cnns Forced With Low-Resolution (120 X 120 Km) Sea Surface High (Ssh) Data And Mesoscale Resolution (12 X 12 Km) Sea Surface Temperature (Sst) Data Allowed Us To Obtain Mesoscale Resolution Sea Surface Currents With Good Accuracy. Sensitivity Experiments Have Shown That Taking Sst Into Account Significantly Increases The Accuracy Of The High-Resolution Velocity Retrieval, Even When Noise Is Added To The Ssh Data. The Velocity Information Embedded In The Transport Equation Modeling The Sst Advection Is Taken Into Account By The Cnn, Which Greatly Increases The Resolution Of Ocean Currents Provided By Ssh. In The Present Work, We Only Consider Spatial Downscaling By Assuming That Ssh And Sst Are Daily Observations. The Method We Developed Is Generic And Can Be Used To Improve The Resolution Of A Wide Variety Of Large-Scale Fields By Merging Them With High-Resolution Fields.
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Thomas, D., Robson, B., & Racoviteanu, A. (2023). An Integrated Deep Learning And Object-Based Image Analysis Approach For Mapping Debris-Covered Glaciers. Frontiers In Remote Sensing, 4.
Abstract: Evaluating Glacial Change And The Subsequent Water Stores In High Mountains Is Becoming Increasingly Necessary, And In Order To Do This, Models Need Reliable And Consistent Glacier Data. These Often Come From Global Inventories, Usually Constructed From Multi-Temporal Satellite Imagery. However, There Are Limitations To These Datasets. While Clean Ice Can Be Mapped Relatively Easily Using Spectral Band Ratios, Mapping Debris-Covered Ice Is More Difficult Due To The Spectral Similarity Of Supraglacial Debris To The Surrounding Terrain. Therefore, Analysts Often Employ Manual Delineation, A Time-Consuming And Subjective Approach To Map Debris-Covered Ice Extents. Given The Increasing Prevalence Of Supraglacial Debris In High Mountain Regions, Such As High Mountain Asia, A Systematic, Objective Approach Is Needed. The Current Study Presents An Approach For Mapping Debris-Covered Glaciers That Integrates A Convolutional Neural Network And Object-Based Image Analysis Into One Seamless Classification Workflow, Applied To Freely Available And Globally Applicable Sentinel-2 Multispectral, Landsat-8 Thermal, Sentinel-1 Interferometric Coherence, And Geomorphometric Datasets. The Approach Is Applied To Three Different Domains In The Central Himalayan And The Karakoram Ranges Of High Mountain Asia That Exhibit Varying Climatic Regimes, Topographies And Debris-Covered Glacier Characteristics. We Evaluate The Performance Of The Approach By Comparison With A Manually Delineated Glacier Inventory, Achieving F-Score Classification Accuracies Of 89.2%-93.7%. We Also Tested The Performance Of This Approach On Declassified Panchromatic 1970 Corona Kh-4B Satellite Imagery In The Manaslu Region Of Nepal, Yielding Accuracies Of Up To 88.4%. We Find Our Approach To Be Robust, Transferable To Other Regions, And Accurate Over Regional (>4,000 Km(2)) Scales. Integrating Object-Based Image Analysis With Deep-Learning Within A Single Workflow Overcomes Shortcomings Associated With Convolutional Neural Network Classifications And Permits A More Flexible And Robust Approach For Mapping Debris-Covered Glaciers. The Novel Automated Processing Of Panchromatic Historical Imagery, Such As Corona Kh-4B, Opens The Possibility Of Exploiting A Wealth Of Multi-Temporal Data To Understand Past Glacier Changes.
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Torresani, L., Piton, G., & D'Agostino, V. (2023). Morphodynamics And Sediment Connectivity Index In An Unmanaged, Debris-Flow Prone Catchment: A Through Time Perspective. Journal Of Mountain Science, , 89188–91099.
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Trabattoni, A., Barruol, G., Dreo, R., & Boudraa, A. (2023). Ship Detection And Tracking From Single Ocean-Bottom Seismic And Hydroacoustic Stations. Journal Of The Acoustical Society Of America, 1531(1), 260–273.
Abstract: We Report In This Study How Ocean-Bottom Seismometers (Obs) Can Be Used As Passive Sonars To Automatically Detect, Localize, And Track Moving Acoustic Sources At The Ocean Surface. We Developed Single-Station Methods Based On Direction Of Arrival And On Multi-Path Interference Measurements Capable Of Handling Continuous Erratic Signals Emitted By Ships. Based On A Bayesian Mathematical Framework, We Developed An Azimuthal Detector And A Radial Detector And Combined Them Into A Fully Automatic Tracker. We Tested The Developed Algorithm On Seismic And Hydroacoustic Data Recorded In The Indian Ocean By An Obs Deployed At 4300 M Depth, 200 Km West Of La Reunion Island. We Quantified The Performances Using Archives Of Commercial-Vessel Trajectories In The Area Provided By The Automatic Identification System. Detectors Demonstrate Capabilities In The Detection Range Up To 100 Km From The Obs With Azimuthal Accuracies Of A Few Degrees And With Distance Accuracies Of A Few Hundred Of Meters. We Expect The Method To Be Easily Transposed To Any Other Kind Of Sources (Such As Marine Mammals).
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Treguier, A., Montegut, C., Bozec, A., Chassignet, E., Fox-Kemper, B., Hogg, A., et al. (2023). The Mixed-Layer Depth In The Ocean Model Intercomparison Project (Omip): Impact Of Resolving Mesoscale Eddies. Geoscientific Model Development, 161(131), 3849–3872.
Abstract: The Ocean Mixed Layer Is The Interface Between The Ocean Interior And The Atmosphere Or Sea Ice And Plays A Key Role In Climate Variability. It Is Thus Critical That Numerical Models Used In Climate Studies Are Capable Of A Good Representation Of The Mixed Layer, Especially Its Depth. Here We Evaluate The Mixed-Layer Depth (Mld) In Six Pairs Of Non Eddying (1 Degrees Grid Spacing) And Eddy-Rich (Up To 1/16 Degrees) Models From The Ocean Model Intercomparison Project (Omip), Forced By A Common Atmospheric State. For Model Evaluation, We Use An Updated Mld Dataset Computed From Observations Using The Omip Protocol (A Constant Density Threshold). In Winter, Low-Resolution Models Exhibit Large Biases In The Deep-Water Formation Regions. These Biases Are Reduced In Eddy-Rich Models But Not Uniformly Across Models And Regions. The Improvement Is Most Noticeable In The Mode Water Formation Regions Of The Northern Hemisphere. Results In The Southern Ocean Are More Contrasted, With Biases Of Either Sign Remaining At High Resolution. In Eddy-Rich Models, Mesoscale Eddies Control The Spatial Variability In Mld In Winter. Contrary To A Hypothesis That The Deepening Of The Mixed Layer In Anticyclones Would Make The Mld Larger Globally, Eddy-Rich Models Tend To Have A Shallower Mixed Layer At Most Latitudes Than Coarser Models Do. In Addition, Our Study Highlights The Sensitivity Of The Mld Computation To The Choice Of A Reference Level And The Spatio-Temporal Sampling, Which Motivates New Recommendations For Mld Computation In Future Model Intercomparison Projects.
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Uchida, T., Jamet, Q., Poje, A., Wienders, N., Dewar, W., & Deremble, B. (2023). Wavelet-Based Wavenumber Spectral Estimate Of Eddy Kinetic Energy: Idealized Quasi-Geostrophic Flow. Journal Of Advances In Modeling Earth Systems, 151(3).
Abstract: A Wavelet-Based Method Is Re-Introduced In An Oceanographic And Spectral Context To Estimate Wavenumber Spectrum And Spectral Flux Of Kinetic Energy And Enstrophy. We Apply This To A Numerical Simulation Of Idealized, Doubly Periodic Quasi-Geostrophic Flows, That Is, The Flow Is Constrained By The Coriolis Force And Vertical Stratification. The Double Periodicity Allows For A Straightforward Fourier Analysis As The Baseline Method. Our Wavelet Spectra Agree Well With The Canonical Fourier Approach But With The Additional Strengths Of Negating The Necessity For The Data To Be Periodic And Being Able To Extract Local Anisotropies In The Flow. Caution Is Warranted, However, When Computing Higher-Order Quantities, Such As Spectral Flux.
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Umlauft, J., Johnson, C., Roux, P., Trugman, D., Lecointre, A., Walpersdorf, A., et al. (2023). Mapping Glacier Basal Sliding Applying Machine Learning. Journal Of Geophysical Research-Earth Surface, 1281(111).
Abstract: During The Resolve Project (“High-Resolution Imaging In Subsurface Geophysics: Development Of A Multi-Instrument Platform For Interdisciplinary Research”), Continuous Surface Displacement And Seismic Array Observations Were Obtained On Glacier D'Argentiere In The French Alps For 35 Days In May 2018. The Data Set Is Used To Perform A Detailed Study Of Targeted Processes Within The Highly Dynamic Cryospheric Environment. In Particular, The Physical Processes Controlling Glacial Basal Motion Are Poorly Understood And Remain Challenging To Observe Directly. Especially In The Alpine Region For Temperate Based Glaciers Where The Ice Rapidly Responds To Changing Climatic Conditions And Thus, Processes Are Strongly Intermittent In Time And Heterogeneous In Space. Spatially Dense Seismic And Global Positioning System (Gps) Measurements Are Analyzed Applying Machine Learning To Gain Insight Into The Processes Controlling Glacial Motions Of Glacier D'Argentiere. Using Multiple Bandpass-Filtered Copies Of The Continuous Seismic Waveforms, We Compute Energy-Based Features, Develop A Matched Field Beamforming Catalog And Include Meteorological Observations. Features Describing The Data Are Analyzed With A Gradient Boosting Decision Tree Model To Directly Estimate The Gps Displacements From The Seismic Noise. We Posit That Features Of The Seismic Noise Provide Direct Access To The Dominant Parameters That Drive Displacement On The Highly Variable And Unsteady Surface Of The Glacier. The Machine Learning Model Infers Daily Fluctuations And Longer Term Trends. The Results Show On-Ice Displacement Rates Are Strongly Modulated By Activity At The Base Of The Glacier. The Techniques Presented Provide A New Approach To Study Glacial Basal Sliding And Discover Its Full Complexity.
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Valenzuela, J., Figueroa, M., Armijos, E., Espinoza, J., Wongchuig, S., & Ramirez-Avila, J. (2023). Flooding Risk Of Cropland Areas By Repiquetes In The Western Amazon Basin: A Case Study Of Peruvian Tamshiyacu City. Journal Of Hydrology-Regional Studies, 474.
Abstract: Study Region: The Western Amazon Basin At Tamshiyacu Gauging Station (Near The Iquitos City) Hosts Floodplain Agriculture That Can Be Affected By The Sudden Reversal In Direction Of Water Levels Known As “Repiquetes” That Produce Intermittent Flooding.Study Focus: This Study Assesses Repiquete Flooding Risk In Riparian Crop Areas Based On Statistical Analyses Of Repiquete Events Registered From 1996 To 2018, Hydraulic Modeling To Estimate Flooded Extension, And Assessment Of Climatological Characteristics During The Formation Of Repiquetes.New Hydrological Insights: Floods (& Ge; 20 Cm) Produced By Repiquetes In Riparian Crop Areas Between 83.00 And 88.00 M Above Sea Level (Masl) Occur 1.8 Times Per Year. However, Not All Elevation Ranges Have The Same Flooding Risk To Crops. Terrain Elevations Between 85.31 And 87.00 Masl Have A Reduced Flooding Risk Of 0.35 Per Year. Likewise, Areas With Elevations Between 87.00 And 88.00 Masl (43% Of The Total Area) Were Not Affected By Repiquetes. Extreme Repiquetes (Study Cases Of 2002 And 2008) Have Been Influenced By The Increase Of Atmospheric Moisture Flux Convergence And Precipitation Over Both The Northern Ucayali And Maran & Sim;& Prime;On Basins Through The Six Previous Days. Flood Impacts From The Extreme Event Of 2002 (2008) Could Have Reached 40% (25%) Of The Available Area For Agriculture At The Initiation Of The Repiquete.
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Valois, R., Derode, B., Vouillamoz, J., Kotchoni, D., Lawson, M., & Rau, G. (2023). Use Of Atmospheric Tides To Estimate The Hydraulic Conductivity Of Confined And Semi-Confined Aquifers. Hydrogeology Journal, .
Abstract: Characterizing Groundwater Responses To Natural Drivers Is Cost Effective And Offers Great Potential In Hydrogeological Inves-Tigations. However, There Is A Lack Of Method Development And Evaluation, For Example By Comparing Results With Those Derived From Using Conventional Methods. This Paper Presents A Modified Method To Calculate The Hydraulic Conductivity (K) Of Confined Aquifers Using The Well Water Response To Atmospheric Tides. The Approach Separates The Earth And Atmospheric Tide Influences On Filtered Well Water-Level Records In The Time Domain. The Resulting Ill-Posed Regression Deconvolution Problem Can Be Overcome By Constraining The Well Water Response To Atmospheric Tides In Order To Follow A Physically Real-Istic Semi-Diurnal Barometric Response Function (S-2-Brf), Or To Follow Directly A Modified Hydraulic Model (Be-Hvorslev) Similar To A Slug Test Evaluation. An Analysis With Synthetic Data Shows That K Up To 10(-4) M/S Can Be Estimated When Pressure Records With Short Sampling Intervals Are Available. Application To A Field Dataset From Cambodia And Benin, With 20-Minute To 60-Minute Sampling Intervals, Respectively, Results In K Values Of 5.82 Center Dot 10(-7) M/S And 2.9<Middle Dot>10(-7) M/S. This Agrees With Results Independently Derived From Pumping Tests For Both Confined Sediments And Semi-Confined Hard-Rock Conditions. This Method Offers A Promising And Low-Cost Approach To Derive K Solely From Monitoring Datasets In Confined Aquifers. This Is Especially Advantageous For Low-Conductivity Formations Where Hydraulic Testing Takes Time.
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Viallon-Galinier, L., Hagenmuller, P., & Eckert, N. (2023). Combining Modelled Snowpack Stability With Machine Learning To Predict Avalanche Activity. Cryosphere, , 224522–226022.
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Vincent, C., & Thibert, E. (2023). Brief Communication: Non-Linear Sensitivity Of Glacier Mass Balance To Climate Attested By Temperature-Index Models. Cryosphere, , 198911–199511.
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Von Schneidemesser, E., Mcdonald, B., Van Der Gon, H., Crippa, M., Guizzardi, D., Borbon, A., et al. (2023). Comparing Urban Anthropogenic Nmvoc Measurements With Representation In Emission Inventories-A Global Perspective. Journal Of Geophysical Research-Atmospheres, .
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Von Schuckmann, K., Miniere, A., Gues, F., Cuesta-Valero, F., Kirchengast, G., Adusumilli, S., et al. (2023). Heat Stored In The Earth System 1960-2020: Where Does The Energy Go? Earth System Science Data, , 167511–170911.
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Wang, Z., Chung, A., Steinhage, D., Parrenin, F., Freitag, J., & Eisen, O. (2023). Mapping Age And Basal Conditions Of Ice In The Dome Fuji Region, Antarctica, By Combining Radar Internal Layer Stratigraphy And Flow Modeling. Cryosphere, 171(101), 4297–4314.
Abstract: The Dome Fuji (Df) Region In Antarctica Is A Potential Site For An Ice Core With A Record Of Over 1 Myr. Here, We Combine Large-Scale Internal Airborne Radar Stratigraphy With A 1-D Model To Estimate The Age Of Basal Ice In The Df Region. The Radar Data Used In The Study Were Collected In A Survey During The 2016-2017 Antarctic Season. We Transfer The Latest Age-Depth Scales From The Df Ice Core To Isochrones Traced In Radargrams In The Surrounding 500 Km X 550 Km Region. At Each Point Of The Survey The 1-D Model Uses The Ages Of Isochrones To Construct The Age-Depth Scale At Depths Where Dated Isochrones Do Not Exist, The Surface Accumulation Rate And The Basal Thermal Condition, Including Melt Rate And The Thickness Of Stagnant Ice. Our Resulting Age Distribution And Age Density Suggest That Several Promising Sites With Ice Older Than 1.5 Myr In The Df Region Might Exist. The Deduced Melt Rates And Presence Of Stagnant Ice Provide More Constraints For Locating Sites With A Cold Base. The Accumulation Rates Range From 0.015 To 0.038 M A-1 Ice Equivalent. Based On Sensitivity Studies We Find That The Number And Depth Of Picked Isochrones And The Timescale Of The Ice Core Severely Affect The Model Results. Our Study Demonstrates That Constraints From Deep Radar Isochrones And A Trustworthy Timescale Could Improve The Model Estimation To Find Old Ice In The Df Region.
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Wharton, G., Phillips, J., Legout, C., & Grabowski, R. (2023). Preface: Understanding Fine Sediment Dynamics In Aquatic Systems. Journal Of Soils And Sediments, 232(101), 3567–3573.
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Willis, M., Lannuzel, D., Else, B., Angot, H., Campbell, K., Crabeck, O., et al. (2023). Polar Oceans And Sea Ice In A Changing Climate. Elementa-Science Of The Anthropocene, 111(1).
Abstract: Polar Oceans And Sea Ice Cover 15% Of The Earth'S Ocean Surface, And The Environment Is Changing Rapidly At Both Poles. Improving Knowledge On The Interactions Between The Atmospheric And Oceanic Realms In The Polar Regions, A Surface Ocean-Lower Atmosphere Study (Solas) Project Key Focus, Is Essential To Understanding The Earth System In The Context Of Climate Change. However, Our Ability To Monitor The Pace And Magnitude Of Changes In The Polar Regions And Evaluate Their Impacts For The Rest Of The Globe Is Limited By Both Remoteness And Sea-Ice Coverage. Sea Ice Not Only Supports Biological Activity And Mediates Gas And Aerosol Exchange But Can Also Hinder Some In-Situ And Remote Sensing Observations. While Satellite Remote Sensing Provides The Baseline Climate Record For Sea-Ice Properties And Extent, These Techniques Cannot Provide Key Variables Within And Below Sea Ice. Recent Robotics, Modeling, And In-Situ Measurement Advances Have Opened New Possibilities For Understanding The Ocean-Sea Ice-Atmosphere System, But Critical Knowledge Gaps Remain. Seasonal And Long-Term Observations Are Clearly Lacking Across All Variables And Phases. Observational And Modeling Efforts Across The Sea-Ice, Ocean, And Atmospheric Domains Must Be Better Linked To Achieve A System-Level Understanding Of Polar Ocean And Sea-Ice Environments. As Polar Oceans Are Warming And Sea Ice Is Becoming Thinner And More Ephemeral Than Before, Dramatic Changes Over A Suite Of Physicochemical And Biogeochemical Processes Are Expected, If Not Already Underway. These Changes In Sea-Ice And Ocean Conditions Will Affect Atmospheric Processes By Modifying The Production Of Aerosols, Aerosol Precursors, Reactive Halogens And Oxidants, And The Exchange Of Greenhouse Gases. Quantifying Which Processes Will Be Enhanced Or Reduced By Climate Change Calls For Tailored Monitoring Programs For High-Latitude Ocean Environments. Open Questions In This Coupled System Will Be Best Resolved By Leveraging Ongoing International And Multidisciplinary Programs, Such As Efforts Led By Solas, To Link Research Across The Ocean-Sea Ice-Atmosphere Interface.
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Wongchuig, S., Espinoza, J., Condom, T., Junquas, C., Sierra, J., Fita, L., et al. (2023). Changes In The Surface And Atmospheric Water Budget Due To Projected Amazon Deforestation: Lessons From A Fully Coupled Model Simulation. Journal Of Hydrology, 6256.
Abstract: The Amazon Forest Has A Complex Interaction With Climate At Different Spatial And Temporal Scales. This Means That Alterations In Land Use Could Modify The Regional Water Cycle, Including The Surface And Atmospheric Water Budget. However, Little Is Known About How These Changes Occur Seasonally And In A Spatially Distributed Manner In The Most Vulnerable Regions, Such As The Southern Amazon. In This Study, The Local To Regional Effects Of Future Amazon Deforestation On The Surface And Atmospheric Water Budget Components Are Investigated By Twin Numerical Experiments Using The Regional Earth System Model Of The 'Institute Pierre Simone Laplace' (Regipsl) For 19 Yr (2001-2019). The Results Show That Significant Changes In Precipitation And Actual Evapotranspiration In The Southern Amazon (South Of 5 Degrees S) Are Associated With Surrounding Areas With A Deforested Ratio Higher Than 40%. During The Onset Of The Wet Season (September-November) The Largest Changes In Convective Processes Are Manifested By Opposite Atmospheric Dynamic In Adjacent Regions (Dipole), Associated With. This Dynamic Is Associated With Wind Orientation And The Different Sizes Of The Straight Corridors Of Continuous Deforestation (Pathways). The Dipole Manifests Itself As A Suppression Of Convection In The Upwind Sector, While Convection Increases In The Downwind Sector Of The Deforestation Pathway. For Medium-Sized Deforestation Pathways (-350 Km) Convection Changes Are Related To Dynamic Processes (Decrease In Surface Roughness). In Large-Sized Pathways (-500 Km) The Mechanisms Causing Convective Changes Are Combined, Dynamic And Thermal (Increase In Surface Temperature). In Deforested Regions There Is An Average Increase Of Terrestrial Water Storage Dynamics And Runoff -10 Times Higher Than In Non-Deforested Regions. Furthermore, The Atmosphere Becomes -8 Times Drier In Deforested Regions Than In Non-Deforested Regions. Our Findings Indicate A New Perspective Regarding A Comprehensive Modeling Approach To Understand Potential Changes In The Surface And Atmospheric Water Cycle In Different Regions Of Amazonia And In Different Seasons Due To Future Deforestation And Thus Provide New Insights Into Their Spatial And Temporal Variability At Sub-Regional Scales.
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Xiong, J., Jiang, L., Qiu, Y., Wongchuig, S., Abishek, Guo, S., et al. (2023). On The Capabilities Of The Swot Satellite To Monitor The Lake Level Change Over The Third Pole. Environmental Research Letters, 181(4).
Abstract: The Lake Level Dynamics Of The Qinghai-Tibetan Plateau (Qtp, Also Called The 'Third Pole') Are A Crucial Indicator Of Climate Change And Human Activities; However, They Remain Poorly Measured Due To Extremely High Elevation And Cold Climate. The Existing Satellite Altimeters Also Suffer From Relatively Coarse Temporal Resolution Or Low Spatial Coverage, Preventing Effective Monitoring Of Lake Level Change At Such A Large Spatial Scale. The Recently Launched Surface Water And Ocean Topography (Swot) Mission Is Expected To Greatly Enhance The Current Lake Level Monitoring Capabilities. However, A Systematic Evaluation Is Still Lacking In The Region. To Elucidate This Potential, Here, We Generated Swot-Like Lake Products For 38 Major Lakes (>150 Km(2)) Over The Qtp During 2000-2018 Using A Large-Scale Swot Hydrology Simulator With The Input Of Satellite Altimetry And Water Mask Databases. The Comparative Assessments Between The Satellite Altimetry Data And Swot Simulations Using Various Statistical Metrics And Decomposed Time Series Components Demonstrate That Swot Can Successfully Monitor Both Short-Term Dynamics And Long-Term Trends. Extended Experiments To Derive Swot-Like Data Of 783 Lakes (>1 Km(2)) Based On The Synthetic Lake Level Series Present The Spatial Pattern Of Swot Performance That Tends To Improve With The Increasing Lake Area. Our Findings Provide Comprehensive Inferences And Confidence For Lake Level Monitoring In The Third Pole In The Early Period Of The Swot Satellite.
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Yue, F., Angot, H., Blomquist, B., Schmale, J., Hoppe, C., Lei, R., et al. (2023). The Marginal Ice Zone As A Dominant Source Region Of Atmospheric Mercury During Central Arctic Summertime. Nature Communications, 141(1).
Abstract: Atmospheric Gaseous Elemental Mercury (Gem) Concentrations In The Arctic Exhibit A Clear Summertime Maximum, While The Origin Of This Peak Is Still A Matter Of Debate In The Community. Based On Summertime Observations During The Multidisciplinary Drifting Observatory For The Study Of Arctic Climate (Mosaic) Expedition And A Modeling Approach, We Further Investigate The Sources Of Atmospheric Hg In The Central Arctic. Simulations With A Generalized Additive Model (Gam) Show That Long-Range Transport Of Anthropogenic And Terrestrial Hg From Lower Latitudes Is A Minor Contribution (Similar To 2%), And More Than 50% Of The Explained Gem Variability Is Caused By Oceanic Evasion. A Potential Source Contribution Function (Pscf) Analysis Further Shows That Oceanic Evasion Is Not Significant Throughout The Ice-Covered Central Arctic Ocean But Mainly Occurs In The Marginal Ice Zone (Miz) Due To The Specific Environmental Conditions In That Region. Our Results Suggest That This Regional Process Could Be The Leading Contributor To The Observed Summertime Gem Maximum. In The Context Of Rapid Arctic Warming And The Observed Increase In Width Of The Miz, Oceanic Hg Evasion May Become More Significant And Strengthen The Role Of The Central Arctic Ocean As A Summertime Source Of Atmospheric Hg.
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Yue, F., Angot, H., Blomquist, B., Schmale, J., Hoppe, C., Lei, R., et al. (2023). The Marginal Ice Zone As A Dominant Source Region Of Atmospheric Mercury During Central Arctic Summertime. Nature Communications, 141(1).
Abstract: Atmospheric Gaseous Elemental Mercury (Gem) Concentrations In The Arctic Exhibit A Clear Summertime Maximum, While The Origin Of This Peak Is Still A Matter Of Debate In The Community. Based On Summertime Observations During The Multidisciplinary Drifting Observatory For The Study Of Arctic Climate (Mosaic) Expedition And A Modeling Approach, We Further Investigate The Sources Of Atmospheric Hg In The Central Arctic. Simulations With A Generalized Additive Model (Gam) Show That Long-Range Transport Of Anthropogenic And Terrestrial Hg From Lower Latitudes Is A Minor Contribution (Similar To 2%), And More Than 50% Of The Explained Gem Variability Is Caused By Oceanic Evasion. A Potential Source Contribution Function (Pscf) Analysis Further Shows That Oceanic Evasion Is Not Significant Throughout The Ice-Covered Central Arctic Ocean But Mainly Occurs In The Marginal Ice Zone (Miz) Due To The Specific Environmental Conditions In That Region. Our Results Suggest That This Regional Process Could Be The Leading Contributor To The Observed Summertime Gem Maximum. In The Context Of Rapid Arctic Warming And The Observed Increase In Width Of The Miz, Oceanic Hg Evasion May Become More Significant And Strengthen The Role Of The Central Arctic Ocean As A Summertime Source Of Atmospheric Hg.
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Zeiger, P., Frappart, F., Darrozes, J., Prigent, C., Jiménez, C., & Bourrel, L. (2023). Weekly Mapping Of Surface Water Extent In The Intertropical Wetlands Using Spaceborne Gnss Reflectometry. Journal Of Hydrology, 6266.
Abstract: As Of Today, The Uncertain Distribution And Dynamics Of Inundations In The Tropical Wetlands Cause Large Uncertainties In The Quantification Of The World'S Methane Emissions. Long-Term, Global Remote Sensing Observations Currently Rely On Optical Sensors, Affected By Cloud Cover And Vegetation, And On Passive Microwave Imagery With A Low Spatial Resolution. Global Navigation Satellite System Reflectometry (Gnss-R) L-Band Observations From Space Onboard The Cyclone Gnss (Cygnss) Mission Can Provide Information About The Dynamics Of Surface Water At Moderate To Low Spatial Resolution And With A Frequent Revisit. In This Article, We Propose A Methodology To Compute The Fraction Of Water Contained In 0.1 Degrees Pixels (Similar To 10 Km) Using Cygnss Reflectivity And Above Ground Biomass (Agb) Maps. We Produced A 1-Year Time Series Of Water Fractions With A Weekly Time Sampling For The Full Coverage Of Cygnss Between +/- 38 Degrees Of Latitude, From August 2018 To July 2019. We Evaluated The Results Against Regional Reference Maps Of Surface Water Based On Modis, Jers-1, And Palsar, And Against The Global Inundation Extent From Multi-Satellite (Giems) Dataset. Cygnss Water Fractions Represent Well The Spatial Distribution And The Seasonality Of Inundation Extent For Most Of The Tropical Wetlands, With A Global Rmsd Of 15.0 % Against Giems. We Found A Likely Overestimation When The Soil Moisture (Sm) Exceeds 0.3-0.4 Cm3/Cm3, I.E. For Saturated Soils Where Gnss-R Reflections Are Coherent, As The Sm Was Not Parameterized In Our Retrieval Model. Despite This, The Results Are Consistent In The Entire Intertropical Band Including Over Densely Vegetated Areas. These Weekly Water Fractions For 2018-2019 With A 0.1 Degrees Pixel Size Are Distributed To Contribute To Further Comparisons And Hydrological Researches.
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Zha, Q., Aliaga, D., Krejci, R., Sinclair, V., Wu, C., Ciarelli, G., et al. (2023). Oxidized Organic Molecules In The Tropical Free Troposphere Over Amazonia. National Science Review, .
Abstract: New Particle Formation (Npf) In The Tropical Free Troposphere (Ft) Is A Globally Important Source Of Cloud Condensation Nuclei, Affecting Cloud Properties And Climate. Oxidized Organic Molecules (Ooms) Produced From Biogenic Volatile Organic Compounds Are Believed To Contribute To Aerosol Formation In The Tropical Ft, But Without Direct Chemical Observations. We Performed In Situ Molecular-Level Ooms Measurements At The Bolivian Station Chacaltaya At 5240 M Above Sea Level, On The Western Edge Of Amazonia. For The First Time, We Demonstrate The Presence Of Ooms, Mainly With 4-5 Carbon Atoms, In Both Gas-Phase And Particle-Phase (In Terms Of Mass Contribution) Measurements In Tropical Ft Air From Amazonia. These Observations, Combined With Air Mass History Analyses, Indicate That The Observed Ooms Are Linked To Isoprene Emitted From The Rainforests Hundreds Of Kilometers Away. Based On Particle-Phase Measurements, We Find That These Compounds Can Contribute To Npf, At Least The Growth Of Newly Formed Nanoparticles, In The Tropical Ft On A Continental Scale. Thus, Our Study Is A Fundamental And Significant Step In Understanding The Aerosol Formation Process In The Tropical Ft. In-Situ Molecular-Level Measurements Demonstrate The Presence Of Oxidized Organic Molecules, Mainly With 4-5 Carbon Atoms, In Both Gas-Phase And Particle-Phase In Tropical Free Troposphere Air From Amazonia. These Molecules Are Linked To Isoprene Emitted From The Rainforests Hundreds Of Kilometers Away, And Can Contribute To New Particle Formation.
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Zha, Q., Huang, W., Aliaga, D., Perakyla, O., Heikkinen, L., Koenig, A., et al. (2023). Measurement Report: Molecular-Level Investigation Of Atmospheric Cluster Ions At The Tropical High-Altitude Research Station Chacaltaya (5240 M A.S.L.) In The Bolivian Andes. Atmospheric Chemistry And Physics, , 455944–457644.
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Zhang, S., Gan, T., Bush, A., Liu, J., Zolina, O., & Gelfan, A. (2023). Changes Of The Streamflow Of Northern River Basins Of Siberia And Their Teleconnections To Climate Patterns. International Journal Of Climatology, .
Abstract: The Arctic Rivers Contribute More Than One-Third Of The Total Freshwater Streamflow Into The Arctic Ocean And Play An Essential Role In The Heat And Mass Circulation Of The Arctic Atmosphere/Ocean System. As The Arctic Is Warming Faster Than The Global Average, The Streamflow From Arctic Basins Increases. This Study Analyzed The Streamflow Of The Three Largest Siberian Rivers: The Lena, Yenisei, And Ob', At Multiple Temporal Scales. Results Show That The Annual Streamflow Of Each River Basin Exhibits Statistically Significant Increasing Trends, While The Seasonal Streamflow Of Sub-Basins Generally Decreases In The Summer But Increases In The Winter. Both Autocorrelation And Long-Term Persistency Are Often Found In The Streamflow Time Series, Which Indicates Significant Changes In The Large-Scale Climatological Environment. Therefore, Wavelet Coherence Between The Streamflow And Large-Scale Climate Patterns, Including The El Nino-Southern Oscillation (Enso), North Pacific Pattern (Np), Arctic Oscillation (Ao), And The Pacific/North America Pattern (Pna), Have Been Conducted. Np And Enso Are Found To Have Positive Relationships With The Precipitation And The Ratio Of Potential Evapotranspiration Over The Precipitation. Ao And The Pna Are Found To Have Positive Relationships With The Streamflow Of The Ob' And Yenisei Rivers At Decadal And Multidecadal Scales. This Study Demonstrates That The Existence Of Nonstationarities Within The Siberian Streamflow As The Combined Impact Of Climate Change Alters The Hydroclimatological And Terrestrial Environment Of Siberia. These Findings Provide New Insights Into The Mechanisms Underlying The Hydrologic Changes To Warming Trends And Oscillations Of Climate Patterns, Which Contribute To Our Understanding And The Prediction Of Streamflow Of These Northern Rivers.
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Zhao, M., Ponte, R., & Penduff, T. (2023). Global-Scale Random Bottom Pressure Fluctuations From Oceanic Intrinsic Variability. Science Advances, 9(292).
Abstract: Intrinsic Processes Such As Mesoscale Turbulence Have Recently Been Proved As Important As Atmospheric Variability In Causing Variations In Ocean Bottom Pressure (P(B)). Intrinsic Processes Are Also Known To Generate Random Variability On Scales Larger Than The Mesoscale Through Inverse Energy Cascades Or Large-Scale Baroclinic Instability. Here, Model Analyses Reveal A Truly Global-Scale, Intrinsic P(B) Mode Of Variability At Monthly Time Scales That Relies On A Different Mechanism. The Intrinsic Mode Has Largest Amplitudes Around Drake Passage And Opposite Polarity Between The Southern Ocean And Atlantic/Arctic Oceans. Its Signature Is Consistent With Localized Eddy-Driven P(B) Anomalies Of Opposite Sign Near Drake Passage That Then Adjust Freely In The Rest Of The Ocean Via Barotropic Wave Processes. This Intrinsic Mode Seems Consistent With Observed P(B) Variability.
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Zheng, Y., Golledge, N., Gossart, A., Picard, G., & Leduc-Leballeur, M. (2023). Statistically Parameterizing And Evaluating A Positive Degree-Day Model To Estimate Surface Melt In Antarctica From 1979 To 2022. Cryosphere, 171(9), 3667–3694.
Abstract: Surface Melting Is One Of The Primary Drivers Of Ice Shelf Collapse In Antarctica And Is Expected To Increase In The Future As The Global Climate Continues To Warm Because There Is A Statistically Significant Positive Relationship Between Air Temperature And Melting. Enhanced Surface Melt Will Impact The Mass Balance Of The Antarctic Ice Sheet (Ais) And, Through Dynamic Feedbacks, Induce Changes In Global Mean Sea Level (Gmsl). However, The Current Understanding Of Surface Melt In Antarctica Remains Limited In Terms Of The Uncertainties In Quantifying Surface Melt And Understanding The Driving Processes Of Surface Melt In Past, Present And Future Contexts. Here, We Construct A Novel Grid-Cell-Level Spatially Distributed Positive Degree-Day (Pdd) Model, Forced With 2 M Air Temperature Reanalysis Data And Spatially Parameterized By Minimizing The Error With Respect To Satellite Estimates And Surface Energy Balance (Seb) Model Outputs On Each Computing Cell Over The Period 1979 To 2022. We Evaluate The Pdd Model By Performing A Goodness-Of-Fit Test And Cross-Validation. We Assess The Accuracy Of Our Parameterization Method, Based On The Performance Of The Pdd Model When Considering All Computing Cells As A Whole, Independently Of The Time Window Chosen For Parameterization. We Conduct A Sensitivity Experiment By Adding +/- 10 % To The Training Data (Satellite Estimates And Seb Model Outputs) Used For Pdd Parameterization And A Sensitivity Experiment By Adding Constant Temperature Perturbations ( + 1 , + 2 , + 3 , + 4 And + 5 Circle C) To The 2 M Air Temperature Field To Force The Pdd Model. We Find That The Pdd Melt Extent And Amounts Change Analogously To The Variations In The Training Data With Steady Statistically Significant Correlations And That The Pdd Melt Amounts Increase Nonlinearly With The Temperature Perturbations, Demonstrating The Consistency Of Our Parameterization And The Applicability Of The Pdd Model To Warmer Climate Scenarios. Within The Limitations Discussed, We Suggest That An Appropriately Parameterized Pdd Model Can Be A Valuable Tool For Exploring Antarctic Surface Melt Beyond The Satellite Era.
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Zou, X., Rowe, P., Gorodetskaya, I., Bromwich, D., Lazzara, M., Cordero, R., et al. (2023). Strong Warming Over The Antarctic Peninsula During Combined Atmospheric River And Foehn Events: Contribution Of Shortwave Radiation And Turbulence. Journal Of Geophysical Research-Atmospheres, 1281(161).
Abstract: The Antarctica Peninsula (Ap) Has Experienced More Frequent And Intense Surface Melting Recently, Jeopardizing The Stability Of Ice Shelves And Ultimately Leading To Ice Loss. Among The Key Phenomena That Can Initiate Surface Melting Are Atmospheric Rivers (Ars) And Leeside Foehn; The Combined Impact Of Ars And Foehn Led To Moderate Surface Warming Over The Ap In December 2018 And Record-Breaking Surface Melting In February 2022. Focusing On The More Intense 2022 Case, This Study Uses High-Resolution Polar Wrf Simulations With Advanced Model Configurations, Reference Elevation Model Of Antarctica Topography, And Observed Surface Albedo To Better Understand The Relationship Between Ars And Foehn And Their Impacts On Surface Warming. With An Intense Ar (Ar3) Intrusion During The 2022 Event, Weak Low-Level Blocking And Heavy Orographic Precipitation On The Upwind Side Resulted In Latent Heat Release, Which Led To A More Deep-Foehn Like Case. On The Leeside, Sensible Heat Flux Associated With The Foehn Magnitude Was The Major Driver During The Night And The Secondary Contributor During The Day Due To A Stationary Orographic Gravity Wave. Downward Shortwave Radiation Was Enhanced Via Cloud Clearance And Dominated Surface Melting During The Daytime, Especially After The Peak Of The Ar/Foehn Events. However, Due To The Complex Terrain Of The Ap, Ars Can Complicate The Foehn Event By Transporting Extra Moisture To The Leeside Via Gap Flows. During The Peak Of The 2022 Foehn Warming, Cloud Formation On The Leeside Hampered The Downward Shortwave Radiation And Slightly Increased The Downward Longwave Radiation.
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2022 |
Ackerer, J., Van Der Woerd, J., Meriaux, A., Ranchoux, C., Schafer, G., Delay, F., et al. (2022). Quantifying Geomorphological Evolution From Be-10 Denudation Rates: Insights From High-Resolution Depth Profiles, Topsoils, And Stream Sediments (Strengbach Czo, France). Earth Surface Processes And Landforms, .
Abstract: A Rare Dataset Of In-Situ Be-10 From High-Resolution Depth Profiles, Soils, Rock Outcrops, And Stream Sediments Is Combined With Geochemical Analysis And Modelling Of Regolith Evolution To Understand The Variability Of Denudation Rates In A Mountain Watershed (Strengbach Critical Zone Observatory). High-Resolution Depth Profiles Are Key To Detect The Presence Of Mobile Regolith And To Highlight How It Affects The Critical Zone Evolution. The Modelling Of Regolith Evolution And Be-10 Concentrations Along Depth Profiles Allow Us To Estimate Both The Cosmic Ray Exposure Age (19 Kyr) And The Mean Denudation Rate (22 Mm Kyr(-1)) Of The Regolith Without Any Steady-State Assumption On Be-10 Concentrations. Comparison With Maximum Denudation Rates Inferred From Topsoil Samples Collected From The Surface Of The Depth Profiles And Calculated Using The Temporal Steady-State Assumption Of Be-10 Concentrations Highlights An Overestimation Of Denudation By A Factor Of Two. Maximum Spatially Averaged Denudation Rates Determined From Stream Sediment Samples Also Likely Overestimate Denudation Rates By A Factor Of Two. These Biases Are Significant For Investigating The Geomorphological Evolution And We Propose A Method To Correct Denudation Rates Using The Inherited Be-10 Concentrations And The Cosmic Ray Exposure Age Deduced From The High-Resolution Depth Profiles. A Key Result Is Also That A Steady State Of Be-10 Concentrations And A Steady State Of Regolith Thickness Are Two Different Equilibrium States That Do Not Necessarily Coincide. The Comparison Between Locally Corrected And Spatially Averaged Denudation Rates Indicates That The Watershed Geomorphology Is Not In A Topographic Steady State But Is Modulated By Regressive Fluvial Erosion. Nonetheless, Our Study Demonstrates That Even In A Watershed Where The Steady-State Assumption Of Be-10 Concentrations Is Not Verified, The Spatial Variations Of In-Situ Be-10 Concentrations In Sediments Still Carry Qualitatively Relevant Information On The Geomorphological Evolution Of Landscapes.
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Ahmed, S., Thomas, J. L., Tuite, K., Stutz, J., Flocke, F., Orlando, J. J., et al. (2022). The Role of Snow in Controlling Halogen Chemistry and Boundary Layer Oxidation During Arctic Spring: A 1D Modeling Case Study. Journal Of Geophysical Research-Atmospheres, 1271(5).
Abstract: Reactive chlorine and bromine species emitted from snow and aerosols can significantly alter the oxidative capacity of the polar boundary layer. However, halogen production mechanisms from snow remain highly uncertain, making it difficult for most models to include descriptions of halogen snow emissions and to understand the impact on atmospheric chemistry. We investigate the influence of Arctic halogen emissions from snow on boundary layer oxidation processes using a one-dimensional atmospheric chemistry and transport model (PACT-1D). To understand the combined impact of snow emissions and boundary layer dynamics on atmospheric chemistry, we model Cl-2 and Br-2 primary emissions from snow and include heterogeneous recycling of halogens on both snow and aerosols. We focus on a 2-day case study from the 2009 Ocean-Atmosphere-Sea Ice-Snowpack campaign at Utqia & x121;vik, Alaska. The model reproduces both the diurnal cycle and high quantity of Cl-2 observed, along with the measured concentrations of Br-2, BrO, and HOBr. Due to the combined effects of emissions, recycling, vertical mixing, and atmospheric chemistry, reactive chlorine is typically confined to the lowest 15 m of the atmosphere, while bromine can impact chemistry up to and above the surface inversion height. Upon including halogen emissions and recycling, the concentration of HOx (HOx = OH + HO2) at the surface increases by as much as a factor of 30 at mid-day. The change in HOx due to halogen chemistry, as well as chlorine atoms derived from snow emissions, significantly reduce volatile organic compound lifetimes within a shallow layer near the surface.
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Al-Yaari, A., Ducharne, A., Thiery, W., Cheruy, F., & Lawrence, D. (2022). The Role Of Irrigation Expansion On Historical Climate Change: Insights From Cmip6. Earths Future, 101(111).
Abstract: To Produce Food For A Growing World Population, Irrigated Areas Have Increased From Approximately 0.63 Million Km(2) Of Land In 1900 To 3.1 Million Km(2) Of Land In 2005. Despite This Massive Expansion, Irrigation Is Still Overlooked In Most State-Of-The-Art Earth System Models (Esms) Involved In The Coupled Model Intercomparison Project Phase 6 (Cmip6). To Our Knowledge, Only Three Cmip6 Models Represent Irrigation Activities: Cesm2, Giss-E2-1-G, And Noresm2-Lm. Here, We Investigate The Role Of Irrigation On Historical Climate At Global And Regional Scales By Analyzing Trends Of Key Surface Climate Variables In Cmip6 Simulations During 1900-2014. The Three Models Including Irrigation Show Distinct Behavior From The 15 Models Without Irrigation Over Intensively Irrigated Areas (I.E., >50% Of Grid Cell Area Is Equipped By Irrigation): Both Annual (Months That Correspond To Monthly Air Temperature Higher Than 274 K) Mean Latent Heat Flux (Lhf) And Soil Moisture Increase Over Time, In Contrast To The Models Without Irrigation That Show No Trend Or Even A Negative Trend. The Positive Lhf Trend Over Intensively Irrigated Areas In The Irrigation-On Models Is Consistent With Three Satellite-Based Lhf Products. While Annual (Considering The Warmest Month In A Year) Warming Trends Are Found In These Regions For Most Of The No-Irrigation Models, The Increase In Lhf Induces A Cooling Trend For The Models With Irrigation, Which Was Not Confirmed By Observational Air Temperature Data Sets. These Findings, Supported By Satellite Data, Indicate The Importance Of Improved Representation Of Land Management In The Next Generation Of Esm.
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Aldana-Dominguez, J., Palomo, I., Arellana, J., & de la Rosa, C. G. (2022). Unpacking The Complexity Of Nature ' S Contributions To Human well-being: lessons to transform the Barranquilla Metropolitan Area into a BiodiverCity. Ecosystems And People, 181(1), 430–446.
Abstract: Rapid urbanization trends and urban lifestyles challenge urban populations to recognize ecosystems' contributions to their well-being, and urban planners to integrate nature at the core of urban development. This study assesses the relationships between ecosystems and people in the rapidly expanding Barranquilla Metropolitan Area (BMA) and extracts lessons for its planning as a BiodiverCity. Using 22 interviews and 400 face-to-face surveys we evaluated: 1) the perception of positive and negative contributions of specific types of ecosystems to human well-being (HWB); 2) the importance and vulnerability of multiple ecosystem services (ES) and disservices (EdS); and 3) the relationships between ES, EdS and relational values (RV), and the influence of socioeconomic factors in providing HWB, using a Structural Equation Model (SEM). Open-ended answers in the survey showed that rural and certain natural ecosystems, such as wetlands, mangroves and tropical dry forest were the least valued ecosystems and included some EdS. In contrast, urban and peri-urban ecosystems, namely the river, beaches, crops, urban green, and backyards, were the most valued. Overall, regulating ES were perceived as critical, as well as important and vulnerable. The results of the SEM model indicate that HWB is not only explained by socioeconomic factors such as income and education, but also by ES. We argue that the necessary sustainable socio-economic development of the BMA should be coupled with an urban planning that integrates ES and their contributions to HWB.
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Amraoui, S., Auroux, D., Blum, J., & Cosme, E. (2022). Back-And-Forth Nudging For The Quasi-Geostrophic Ocean Dynamics With Altimetry: Theoretical Convergence Study And Numerical Experiments With The Future Swot Observations. Discrete And Continuous Dynamical Systems-Series S, .
Abstract: In data assimilation for geophysical problems, the increasing amount of satellite data to analyze makes it more and more challenging to guarantee near real time forecasting. Thus, low time and memory consuming data assimilation methods become very attractive. The back-and-forth nudging (BFN) method is a non-classical data assimilation method that can be seen as a deterministic and smoothing version of the Kalman filter. From a practical point of view, the BFN method is very valuable for its simplicity of implementation (no optimization, no differentiation,...) and its rapidity of convergence. Under observability conditions, we prove the mathematical convergence of BFN at deep layers for a multi-layer quasi-geostrophic (MQG) ocean circulation model using an infinite dimensional variant of LaSalle's invariance principle. We also extend the BFN to the problem of joint state-parameter identification. The numerical experiments, performed on 120km large swath sea surface height (SSH) simulated data of the Surface Water Ocean Topography (SWOT) satellite, show the high robustness of the algorithm to uncertainties and the few iterations needed to reach convergence, whereas some problems remain due to non-reversibility properties in time. We also give a strategy to improve geophysical model accuracy, considering the large number of uncertain parameters inherent to models and their impacts on state estimation performance. We propose here a joint state-parameter estimation, tested on the baroclinic wavenumber as an unobserved parameter.
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Angot, H., Blomquist, B., Howard, D., Archer, S., Bariteau, L., Beck, I., et al. (2022). Year-Round Trace Gas Measurements In The Central Arctic During The Mosaic Expedition. Scientific Data, 9(1).
Abstract: Despite The Key Role Of The Arctic In The Global Earth System, Year-Round In-Situ Atmospheric Composition Observations Within The Arctic Are Sparse And Mostly Rely On Measurements At Ground-Based Coastal Stations. Measurements Of A Suite Of In-Situ Trace Gases Were Performed In The Central Arctic During The Multidisciplinary Drifting Observatory For The Study Of Arctic Climate (Mosaic) Expedition. These Observations Give A Comprehensive Picture Of Year-Round Near-Surface Atmospheric Abundances Of Key Greenhouse And Trace Gases, I.E., Carbon Dioxide, Methane, Nitrous Oxide, Ozone, Carbon Monoxide, Dimethylsulfide, Sulfur Dioxide, Elemental Mercury, And Selected Volatile Organic Compounds (Vocs). Redundancy In Certain Measurements Supported Continuity And Permitted Cross-Evaluation And Validation Of The Data. This Paper Gives An Overview Of The Trace Gas Measurements Conducted During Mosaic And Highlights The High Quality Of The Monitoring Activities. In Addition, In The Case Of Redundant Measurements, Merged Datasets Are Provided And Recommended For Further Use By The Scientific Community.
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Araujo, B., Osterwalder, S., Szponar, N., Lee, D., Petrova, M., Pernov, J., et al. (2022). Mercury Isotope Evidence For Arctic Summertime Re-Emission Of Mercury From The Cryosphere. Nature Communications, 131(1).
Abstract: During Arctic Springtime, Halogen Radicals Oxidize Atmospheric Elemental Mercury (Hg-0), Which Deposits To The Cryosphere. This Is Followed By A Summertime Atmospheric Hg-0 Peak That Is Thought To Result Mostly From Terrestrial Hg Inputs To The Arctic Ocean, Followed By Photoreduction And Emission To Air. The Large Terrestrial Hg Contribution To The Arctic Ocean And Global Atmosphere Has Raised Concern Over The Potential Release Of Permafrost Hg, Via Rivers And Coastal Erosion, With Arctic Warming. Here We Investigate Hg Isotope Variability Of Arctic Atmospheric, Marine, And Terrestrial Hg. We Observe Highly Characteristic Hg Isotope Signatures During The Summertime Peak That Reflect Re-Emission Of Hg Deposited To The Cryosphere During Spring. Air Mass Back Trajectories Support A Cryospheric Hg Emission Source But No Major Terrestrial Source. This Implies That Terrestrial Hg Inputs To The Arctic Ocean Remain In The Marine Ecosystem, Without Substantial Loss To The Global Atmosphere, But With Possible Effects On Food Webs. Arctic Warming Thaws Permafrost, Leading To Enhanced Soil Mercury Transport To The Arctic Ocean. Mercury Isotope Signatures In Arctic Rivers, Ocean And Atmosphere Suggest That Permafrost Mercury Is Buried In Marine Sediment And Not Emitted To The Global Atmosphere
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Argueso, D., Di Luca, A., Jourdain, N., Romero, R., & Homar, V. (2022). Mechanisms For Extreme Precipitation Changes In A Tropical Archipelago. Journal Of Climate, 353(171), 5519–5536.
Abstract: The Maritime Continent Is One Of The Most Challenging Regions For Atmospheric Models. Processes That Modulate Deep Convection Are Poorly Represented In Models, Which Affects Their Ability To Simulate Precipitation Features Accurately. Thus, Future Projections Of Precipitation Over The Region Are Prone To Large Uncertainties. One Of The Key Players In Modeling Tropical Precipitation Is The Convective Representation, And Hence Convection-Permitting Experiments Have Contributed To Improve Aspects Of Precipitation In Models. This Improvement Creates Opportunities To Explore The Physical Processes That Govern Rainfall In The Maritime Continent, As Well As Their Role In A Warming Climate. Here, We Examine The Response To Climate Change Of Models With Explicit And Parameterized Convection And How That Reflects In Precipitation Changes. We Focus On The Intensification Of Spatial Contrasts As Precursors Of Changes In Mean And Extreme Precipitation In The Tropical Archipelago. Our Results Show That The Broad Picture Is Similar In Both Model Setups, Where Islands Will Undergo An Increase In Mean And Extreme Precipitation In A Warmer Climate And The Ocean Will See Less Rain. However, The Magnitude And Spatial Structure Of Such Changes, As Well As The Projection Of Rainfall Percentiles, Are Different Across Model Experiments. We Suggest That While The Primary Effect Of Climate Change Is Thermodynamical And It Is Similarly Reproduced By Both Model Configurations, Dynamical Effects Are Represented Quite Differently In Explicit And Parameterized Convection Experiments. In This Study, We Link Such Differences To Horizontal And Vertical Spatial Contrasts And How Convective Representations Translate Them Into Precipitation Changes.
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Autin, P., Sicart, J. E., Rabatel, A., Soruco, A., & Hock, R. (2022). Climate Controls On The Interseasonal And Interannual Variability Of The Surface Mass and Energy Balances of a Tropical Glacier (Zongo Glacier, Bolivia, 16 degrees S): New Insights From the Multi-Year Application of a Distributed Energy Balance Model. Journal Of Geophysical Research-Atmospheres, 1271(7).
Abstract: The application of a distributed energy balance model over nine years at an hourly time step to a 20 x 20 m grid cell over Glacier Zongo (Bolivia, 16 degrees S) enabled assessment of the climate factors that control the interseasonal and interannual variability of its surface mass balance. The model was validated by comparing the measured and simulated discharge at the outlet, albedo at the Automatic Weather Station, surface state and annual mass balance both glacier-wide and as a function of altitude. Analysis of the mean monthly energy fluxes highlighted the importance of the meteorological conditions over October and November on the variability of the annual surface mass balance. Two sensitivity analyses are presented, one of the distribution of precipitation over time which maintains a physical coherence between the different meteorological variables and one of the impact of prolonged periods of intense cloud radiative forcing on the surface mass balance. The distribution of precipitation events over time and their associated amounts are the main drivers of the interannual variability of the surface mass balance via an albedo feedback effect. Additionally, prolonged periods of negative cloud radiative forcing, specifically over the month of November, notably reduce the melt rate.
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Aviles, G. P. F., Spadini, L., Sacchi, E., Rossier, Y., Savarino, J., Ramos, O. E., et al. (2022). Hydrogeochemical and nitrate isotopic evolution of a semiarid mountainous basin aquifer of glacial-fluvial and paleolacustrine origin (Lake Titicaca, Bolivia): the effects of natural processes and anthropogenic activities. Hydrogeology Journal, 303(1), 181–201.
Abstract: A hydrogeochemical and stable isotopic (delta(15) N-NO3 and delta O-18(NO3)) multitracer approach was combined with previous geological and hydrogeological knowledge in a groundwater-dominated basin, located within the semiarid region of the Bolivian Altiplano (SE of Lake Titicaca). Major natural processes and anthropogenic impacts controlling water chemistry and isotopic compositions of groundwater were identified and corresponding aquifer impacted zones determined. The main natural processes are, by following water flowlines, (1) silicate weathering in the piedmont subsystem (similar to 4,600-3,910 m asl, Ca(Mg)HCO3 facies), (2) Na-Ca exchange within glacial-fluvial deposits overlying paleolacustrine deposits (similar to 3,910 to 3,860 m asl, Na-HCO3 facies), and (3) evaporite dissolution in the confined zone of the lacustrine plain (similar to 3,860-3,810 m asl, Na-Cl-SO4 facies). The highest contributions of anthropogenic nitrate in groundwater have been observed at 3,960-3,860 m asl in the piedmont subsystem and were isotopically associated with leaching from areas influenced by manure piles, synthetic N fertilizers, and sewage collector pipes. In this subsystem, natural water-rock interactions could be deciphered with minimal anthropogenic impact, allowing nitrate sources to be clearly identified. Denitrification, occurring in the topographic lows of the piedmont subsystem, was identified as the main natural attenuation process. The multitracer approach provided a consistent understanding of the major processes that take place along the groundwater flow system and confirmed the significant role of anthropogenic nitrate. This aquifer system thus represents an ideal model of the region's hydrochemical evolution along the gravity-driven flow caused by natural water-rock interaction processes and the influence of anthropogenic contamination.
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Bakker, M., Legout, C., Gimbert, F., Nord, G., Boudevillain, B., & Freche, G. (2022). Seismic Modelling And Observations Of Rainfall. Journal Of Hydrology, 6106.
Abstract: Rainfall is a key driver of geomorphological processes ranging from impacting drops that lead to the small-scale dislodgement of soil particles to large-scale morphogenic floods and rainfall-induced hillslope processes. Although rainfall has been identified in seismic records, the associated power spectral density and its quantitative relation to the underlying physical processes have not yet been studied. Here, we analyze nearly 2 years of combined seismic and optical disdrometer measurements, where the latter enables the drop-based quantification of rainfall physical properties. Our measurements confirm the broadband observation of ground velocity power spectral density due to rainfall, allowing the seismic identification of rainfall at intensities as low as 1 mm/h. Seismic power, P, shows a power-law scaling with rainfall intensity, I, and kinetic energy, E: P proportional to I-2.1 and P proportional to E-1.6. The observed scaling relations are consistent between the three monitored sites although there are absolute differences in seismic power of about 1 order of magnitude, which are likely due to variability in landcover and subsurface seismic properties. With a physical model, we demonstrate that the observed power-law relations are set by an underlying linear relation between seismic power and rainfall impulse power, and that the associated exponent values of I and E are due to the covariance of the raindrop size distribution with the total number of drops. The largest raindrop fractions, whose relative contribution increases with rainfall intensity, dominate the seismic signal where, in our case, 90% of the seismic power is attributed to drops larger than 3 mm. Using our model, we estimate the contributing area of rainfall to seismic observations to be within a radial distance of -5-25 m. The spatially integrated nature of the seismic measurements and their sensitivity to large raindrops, which control the disaggregation and the mobilization of soil particles, make seismic records well-suited for the investigation of soil erosion processes. More generally, our work provides a basis for the temporally-resolved seismic quantification of rainfall that drives the dynamics of various hydro-geomorphological processes.
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Bakker, M., Legout, C., Gimbert, F., Nord, G., Boudevillain, B., & Freche, G. (2022). Seismic Modelling And Observations Of Rainfall. Journal Of Hydrology, 6106.
Abstract: Rainfall is a key driver of geomorphological processes ranging from impacting drops that lead to the small-scale dislodgement of soil particles to large-scale morphogenic floods and rainfall-induced hillslope processes. Although rainfall has been identified in seismic records, the associated power spectral density and its quantitative relation to the underlying physical processes have not yet been studied. Here, we analyze nearly 2 years of combined seismic and optical disdrometer measurements, where the latter enables the drop-based quantification of rainfall physical properties. Our measurements confirm the broadband observation of ground velocity power spectral density due to rainfall, allowing the seismic identification of rainfall at intensities as low as 1 mm/h. Seismic power, P, shows a power-law scaling with rainfall intensity, I, and kinetic energy, E: P proportional to I-2.1 and P proportional to E-1.6. The observed scaling relations are consistent between the three monitored sites although there are absolute differences in seismic power of about 1 order of magnitude, which are likely due to variability in landcover and subsurface seismic properties. With a physical model, we demonstrate that the observed power-law relations are set by an underlying linear relation between seismic power and rainfall impulse power, and that the associated exponent values of I and E are due to the covariance of the raindrop size distribution with the total number of drops. The largest raindrop fractions, whose relative contribution increases with rainfall intensity, dominate the seismic signal where, in our case, 90% of the seismic power is attributed to drops larger than 3 mm. Using our model, we estimate the contributing area of rainfall to seismic observations to be within a radial distance of -5-25 m. The spatially integrated nature of the seismic measurements and their sensitivity to large raindrops, which control the disaggregation and the mobilization of soil particles, make seismic records well-suited for the investigation of soil erosion processes. More generally, our work provides a basis for the temporally-resolved seismic quantification of rainfall that drives the dynamics of various hydro-geomorphological processes.
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Baladima, F., Thomas, J. L., Voisin, D., Dumont, M., Junquas, C., Kumar, R., et al. (2022). Modeling An Extreme Dust Deposition Event To The French Alpine Seasonal Snowpack in April 2018: Meteorological Context and Predictions of Dust Deposition. Journal Of Geophysical Research-Atmospheres, 1271(8).
Abstract: Mineral dust is an important aerosol in the atmosphere and is known to reduce snow albedo upon deposition. Model predictions of dust deposition events in snow covered mountain regions are challenging due to the complexity of aerosol-cloud interactions and the specifics of mountain meteorological systems. We use a case study of dust deposition between 30 March and 5 April 2018 to the French alpine snowpack to study the processes that control dust deposition to the seasonal snowpack. To understand processes controlling dust transport and deposition to snow, we use a combination of in situ observations at Col du Lautaret in the French Alps, satellite remote sensing, the Copernicus Atmosphere Monitoring Service (CAMS) reanalysis global atmospheric composition, and the regional model WRF-Chem. Specifically, we investigate the role of increased model spatial resolution within WRF-Chem in capturing mountain meteorology, precipitation, and predicted dust deposition. Regional model results are also compared to the reanalysis global CAMS products including aerosols in the atmosphere and predicted dust deposition fluxes. We conclude that predicted mountain meteorology (e.g., precipitation) is better with increased model resolution (3 x 3 km resolution WRF-Chem domain). This improved meteorology has significant impacts on predicted dry and wet dust deposition to the alpine snowpack. Dry deposition is important in the western part of the French Alps at low altitudes, while wet deposition dominates over the complex higher altitude mountain terrain.
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Barbero, A., Grilli, R., Frey, M., Blouzon, C., Helmig, D., Caillon, N., et al. (2022). Summer Variability Of The Atmospheric No2 : No Ratio A Dome C On The East Antarctic Plateau. Atmospheric Chemistry And Physics, 222(181), 12025–12054.
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Basantes-Serrano, R., Rabatel, A., Francou, B., Vincent, C., Soruco, A., Condom, T., et al. (2022). New Insights Into The Decadal Variability In Glacier Volume Of A Tropical Ice Cap, Antisana (0 Degrees 29 ' S, 78 Degrees 09 ' W), Explained By The Morpho-Topographic And Climatic Context. Cryosphere, 161(111), 4659–4677.
Abstract: We Present A Comprehensive Study Of The Evolution Of The Glaciers On The Antisana Ice Cap (Tropical Andes) Over The Period 1956-2016. Based On Geodetic Observations Of Aerial Photographs And High-Resolution Satellite Images, We Explore The Effects Of Morpho-Topographic And Climate Variables On Glacier Volumes. Contrasting Behaviour Was Observed Over The Whole Period, With Two Periods Of Strong Mass Loss, 1956-1964 (-0.72 M W.E. Yr(-1)) And 1979-1997 (-0.82 M W.E. Yr(-1)), And Two Periods With Slight Mass Loss, 1965-1978 (0.10 M W.E. Yr(-1)) And 1998-2016 (-0.26 M W.E. Yr(-1)). There Was A 42 % Reduction In The Total Surface Area Of The Ice Cap. Individually, Glacier Responses Were Modulated By Morpho-Topographic Variables (E.G. Maximum And Median Altitude And Surface Area), Particularly In The Case Of The Small Tongues Located At Low Elevations (Glacier 1, 5 And 16) Which Have Been Undergoing Accelerated Disintegration Since The 1990S And Will Likely Disappear In The Coming Years. Moreover, Thanks To The Availability Of Aerial Data, A Surging Event Was Detected On The Antisana Glacier 8 (G8) In The 2009-2011 Period; Such An Event Is Extremely Rare In This Region And Deserves A Dedicated Study. Despite The Effect Of The Complex Topography, Glaciers Have Reacted In Agreement With Changes In Climate Forcing, With A Stepwise Transition Towards Warmer And Alternating Wet-Dry Conditions Since The Mid-1970S. Long-Term Decadal Variability Is Consistent With The Warm-Cold Conditions Observed In The Pacific Ocean Represented By The Southern Oscillation Index.
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Bayle, A., Roy, A., Dedieu, J. P., Boudreau, S., Choler, P., & Levesque, E. (2022). Two Distinct Waves Of Greening In Northeastern Canada: Summer Warming does not tell the whole story. Environmental Research Letters, 171(6).
Abstract: Arctic vegetation cover has been increasing over the last 40 years, which has been attributed mostly to increases in temperature. Yet, the temporal dimension of this greening remains overlooked as it is often viewed as a monotonic trend. Here, using 11 year long rolling windows on 30 m resolution Landsat data, we examined the temporal variations in greening in north-eastern Canada and its dependence on summer warming. We found two significant and distinct waves of greening, centred around 1996 and 2011, and observed in all land cover types (from boreal forest to arctic tundra). The first wave was more intense and correlated with increasing summer temperature while no such relation was found for the weaker second wave. More specifically, the greening lasted longer at higher elevation during the first wave which translates to a prolonged correlation between greening and summer warming compared to low-altitude vegetation. Our work explored a forsaken complexity of high latitude greening trends and associated drivers and has raised new questions that warrant further research highlighting the importance to include temporal dimension to greening analyses in conjunction with common spatial gradients.
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Becagli, S., Barbaro, E., Bonamano, S., Caiazzo, L., di Sarra, A., Feltracco, M., et al. (2022). Factors Controlling Atmospheric Dms And Its Oxidation Products (Msa And nssSO(4)(2-)) in the aerosol at Terra Nova Bay, Antarctica. Atmospheric Chemistry And Physics, 222(141), 9245–9263.
Abstract: This paper presents the results of simultaneous high time-resolution measurements of biogenic aerosol (methane sulfonic acid (MSA), non-sea salt sulfate nssSO(4)(2-)) with its gaseous precursor dimethylsulfide (DMS), performed at the Italian coastal base Mario Zucchelli Station (MZS) in Terra Nova Bay (MZS) during two summer campaigns (2018-2019 and 2019-2020). Data on atmospheric DMS concentration are scarce, especially in Antarctica. The DMS maximum at MZS occurs in December, one month earlier than at other Antarctic stations. The maximum of DMS concentration is connected with the phytoplanktonic senescent phase following the bloom of Phaeocystis antarctica that occurs in the polynya when sea ice opens up. The second plankton bloom occurs in January and, despite the high dimethylsufoniopropionate (DMSP) concentration in seawater, atmospheric DMS remains low, probably due to its fast biological turnover in seawater in this period. The intensity and timing of the DMS evolution during the two years suggest that only the portion of the polynya close to the sampling site produces a discernible effect on the measured DMS. The closeness to the DMS source area and the occurrence of air masses containing DMS and freshly formed oxidation products allow us to study the kinetic of biogenic aerosol formation and the reliable derivation of the branch ratio between MSA and nssSO(4)(2-) from DMS oxidation that is estimated to be 0.84 +/- 0.06. Conversely, for aged air masses with low DMS content, an enrichment of nssSO(4)(2-) with respect to MSA, is observed. We estimate that the mean contribution of freshly formed biogenic aerosol to PM10 is 17 % with a maximum of 56 %. The high contribution of biogenic aerosol to the total PM10 mass in summer in this area highlights the dominant role of the polynya on biogenic aerosol formation. Finally, due to the regional and year-to-year variability of DMS and related biogenic aerosol formation, we stress the need for long-term measurements of seawater and atmospheric DMS and biogenic aerosol along the Antarctic coast and in the Southern Ocean.
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Becquet, J., Lamouroux, N., Condom, T., Gouttevin, I., Forcellini, M., Launay, B., et al. (2022). Macroinvertebrate Distribution Associated With Environmental Variables In Alpine Streams. Freshwater Biology, .
Abstract: Ongoing Hydrological Alterations Due To Climate Change And Anthropogenic Uses Of Water Have Major Implications For Freshwater Biodiversity. Quantifying The Relative Effects Of Environmental Variables On Macroinvertebrates Is Required To Predict Biological Responses To Hydrological Alterations. To Date, No Study Simultaneously Examined The Effects Of Physico-Chemistry, Hydraulics, And Hydrology On The Distribution Of Alpine Macroinvertebrate Communities And Taxa. In This Study, We Aimed To Quantify The Relative Correlation Between These Environmental Variables And Macroinvertebrate Community Composition And Structure. We Sampled Macroinvertebrates At 66 Stream Sites Located In Three Catchments In The French Alps. We Characterised The Proximate Habitat At Each Site Using 11 Variables Describing Measured Physico-Chemistry And Hydraulics, And Simulation-Based Hydrology. We Described Relationships Between Community Structure And The Environment Using A Co-Inertia Analysis And Modelled Individual Taxa Abundance With Generalised Linear Mixed Models. The Co-Inertia Revealed A Significant Co-Structure Between The Environmental And Macroinvertebrate Matrices. Glacier-Influenced Sites With High Turbidity And Summer Flow Exhibited Similar Community Composition With Low Total Abundance. Sources At High Altitude And Sites With Low Glacial Influence, Exhibiting High Summer Flow And Flow Velocity, Were Dominated By Diamesinae, Rhithrogena Spp., Dictyogenus Spp., And Baetis Alpinus. Streams Fed By Rainfall/Snowmelt And Valley Sources, Associated With Higher Temperature, Conductivity, And Monthly Discharge Variability Were Characterised By Higher Richness And Abundances. Models Indicated That The Three Types Of Proximate Habitat Variables Significantly Contributed To The Macroinvertebrate Distribution. Turbidity Was Strongly Negatively Associated With Macroinvertebrate Abundances. Increasing Flow Velocity And Summer Flow Had Significant (Mainly Negative) Effect In 43% Of Models. The Co-Structure Between Communities And Proximate Habitat Variables Was Shared By The Three Catchments. For Most Individual Taxa, Catchment Identity Did Not Influence Abundance Models And Cross-Validations Indicated Transferable Effects Of Proximate Habitat Variables Among Alpine Catchments. Our Results Can Be Used To Infer Responses Of Alpine Macroinvertebrates To Multivariate Environmental Changes. Understanding The Relationships Between Macroinvertebrates And Environmental Variables Help To Predict How Communities And Taxa Will Be Affected By Habitat Alterations Due To Ongoing Hydrological Changes And Resulting Physico-Chemical Conditions.
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Benavent, N., Mahajan, A., Li, Q., Cuevas, C., Schmale, J., Angot, H., et al. (2022). Substantial Contribution Of Iodine To Arctic Ozone Destruction. Nature Geoscience, .
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Beraud, L., Cusicanqui, D., Rabatel, A., Brun, F., Vincent, C., & Six, D. (2022). Glacier-Wide Seasonal And Annual Geodetic Mass Balances From Pleiades Stereo Images: Application To The Glacier D'Argentiere, French Alps. Journal Of Glaciology, .
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Bernard, A., Hagenmuller, P., Montagnat, M., & Chambon, G. (2022). Disentangling Creep And Isothermal Metamorphism During Snow Settlement With X-Ray Tomography. Journal Of Glaciology, .
Abstract: Once Fallen, Snow Settles Due To The Combined Effects Of Metamorphism And Deformation Of The Ice Matrix Under Gravity. To Understand How These Coupled Processes Affect Snow Evolution, We Performed Oedometric Compression Tests And Continuously Monitored The Snow Microstructure.With X-Ray Tomography. Centimetric Samples With An Initial Density Between 200 And 300 Kgm(-3) Were Followed During An Initial Sintering Phase And Under Two Different Loads Of 2.1 And 4.7 Kpa At -8 Degrees C For Similar To 1 Week. The Microstructure Captured At A Voxel Size Of 8.5 Mu M Was Characterized By Density, Specific Surface Area (Ssa) And Two Metrics Related To Bond Network, Namely The Euler Characteristic And The Minimum Cut Surface. Load-Induced Creep Of The Ice Matrix Was Observed Only For Sufficiently Low Values Of Initial Density (<290 Kgm(-3) In Our Tests), And Was Shown To Be Associated To A Significant Increase Of The Number Of Bonds. Application Of The Load, However, Did Not Affect The Individual Bond Size Nor The Ssa, Which Appeared To Be Mainly Controlled By Isothermal Metamorphism. The Uniaxial Compression Did Not Induce Any Creation Of Anisotropy On The Microstructural Characteristics. Overall, Our Results Show That, For The Considered Conditions, The Deformation Of The Ice Matrix Mainly Leads To A Reduction Of The Pore Space And An Increase Of The Coordination Number, While Metamorphism Mainly Affects The Grain And Bond Sizes.
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Bessin, Z., Dedieu, J. P., Arnaud, Y., Wagnon, P., Brun, F., Esteves, M., et al. (2022). Processing of VEN μS Images of High Mountains: A Case Study for Cryospheric and Hydro-Climatic Applications in the Everest Region (Nepal). Remote Sensing, 141(5).
Abstract: In the Central Himalayas, glaciers and snowmelt play an important hydrological role, as they ensure the availability of surface water outside the monsoon period. To compensate for the lack of field measurements in glaciology and hydrology, high temporal and spatial resolution optical remotely sensed data are necessary. The French-Israeli VEN μS Earth observation mission has been able to complement field measurements since 2017. The aim of this paper is to evaluate the performance of different reflectance products over the Everest region for constraining the energy balance of glaciers and for cloud and snow cover mapping applied to hydrology. Firstly, the results indicate that a complete radiometric correction of slope effects such as the Gamma one (direct and diffuse illumination) provides better temporal and statistical metrics (R-2 = 0.73 and RMSE = 0.11) versus ground albedo datasets than a single cosine correction, even processed under a fine-resolution digital elevation model (DEM). Secondly, a mixed spectral-textural approach on the VEN μS images strongly improves the cloud mapping by 15% compared with a spectral mask thresholding process. These findings will improve the accuracy of snow cover mapping over the watershed areas downstream of the Everest region.
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Bianchi, F., Sinclair, V. A., Aliaga, D., Zha, Q. Z., Scholz, W., Wu, C., et al. (2022). The Saltena Experiment Comprehensive Observations Of Aerosol Sources, Formation, and Processes in the South American Andes. Bulletin Of The American Meteorological Society, 1031(2), E212–E229.
Abstract: This paper presents an introduction to the Southern Hemisphere High Altitude Experiment on Particle Nucleation and Growth (SALTENA). This field campaign took place between December 2017 and June 2018 (wet to dry season) at Chacaltaya (CHC), a GAW (Global Atmosphere Watch) station located at 5,240 m MSL in the Bolivian Andes. Concurrent measurements were conducted at two additional sites in El Alto (4,000 m MSL) and La Paz (3,600 m MSL). The overall goal of the campaign was to identify the sources, understand the formation mechanisms and transport, and characterize the properties of aerosol at these stations. State-of-the-art instruments were brought to the station complementing the ongoing permanent GAW measurements, to allow a comprehensive description of the chemical species of anthropogenic and biogenic origin impacting the station and contributing to new particle formation. In this overview we first provide an assessment of the complex meteorology, airmass origin, and boundary layer-free troposphere interactions during the campaign using a 6-month high-resolution Weather Research and Forecasting (WRF) simulation coupled with Flexible Particle dispersion model (FLEXPART). We then show some of the research highlights from the campaign, including (i) chemical transformation processes of anthropogenic pollution while the air masses are transported to the CHC station from the metropolitan area of La Paz- El Alto, (ii) volcanic emissions as an important source of atmospheric sulfur compounds in the region, (iii) the characterization of the compounds involved in new particle formation, and (iv) the identification of long-range-transported compounds from the Pacific or the Amazon basin. We conclude the article with a presentation of future research foci. The SALTENA dataset highlights the importance of comprehensive observations in strategic high-altitude locations, especially the undersampled Southern Hemisphere.
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Blanchet, J., & Creutin, J. D. (2022). Instrumental Agreement And Retrospective Analysis Of Trends In precipitation extremes in the French Mediterranean Region. Environmental Research Letters, 171(7).
Abstract: In this letter we show the emergence of an agreement between the instruments of a rain-gauge network to point toward a positive trend in daily precipitation extremes since 1960 in the French Mediterranean Region. We identify for each gauge the time varying parameters of the generalized extreme value distribution of annual maximum precipitation over incremental time-windows. These distributions provide for each station of the network a trend assessment over a chosen period that can be interpreted for instance as a trend of the mean or as the trend of a chosen quantile. The incremental window, i.e. a window containing the series of data available at a given date, mimics the annual assessment of the trends that could have been made through time. Each year we thus have one trend per gauge that we can look in distribution through the network in order to assess the level of consensus among instruments. We show how the increasing size of the datasets used over a period of possible climate non-stationarity progressively leads from a dissensus anarchically pointing to no trend (before the 2000s) to a consensus where a majority of gauges points toward a positive trend (after the 2000s). The detected trend in this Mediterranean Region is quite substantial. For instance the 20 year return period precipitation in 1960 turns out to become a 8 year return period precipitation in 2020. Using a simulation basis we try to characterize the effect of decadal variability that is quite readable in the consensus evolution. The proposed metrics is thought to be a good candidate for the assessment of the local time and rate of emergence of climate change that has important implications in regards to adaptation of human and natural systems.
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Boisson, E., Wilhelm, B., Garnier, E., Melo, A., Anquetin, S., & Ruin, I. (2022). Geo-historical database of flood impacts in Alpine catchments (HIFAVa database, Arve River, France, 1850-2015). Natural Hazards And Earth System Sciences, 222(3), 831–847.
Abstract: In France, flooding is the most common and damaging natural hazard (CCR, 2021). Global warming is expected to exacerbate flood risk and could be more pronounced in the European Alps which are experiencing a high warming rate, likely to lead to heavier rainfall events. Alpine valleys are densely populated, potentially increasing exposure and vulnerability to flood hazard. The study of historical records is highly relevant to understand long-term flood occurrence and related socio-economic impacts in relation to changes in the flood risk components (i.e. hazard, exposure and vulnerability). To this aim we introduce the newly constituted database of Historical Impacts of Floods in the Arve Valley (HIFAVa) located in the French northern Alps starting in 1850. This quite unique database reports historical impacts related to impact events occurrences in a well-documented Alpine catchment that encompasses both hydrological and socio-economical diversity. After a complete description of the database (collection, content and structure), we explore the distribution of the recorded impacts with respect to their characteristics and evolution in both time and space. The analysis reveals that small mountain streams and particularly glacial streams caused more impacts (67 %) than the main river. While an increase in heavy rainfall and ice melt are expected to enhance flood hazard in small Alpine catchments, this finding calls for greater attention to flood risk assessment and management in small catchments. The analysis also reveals an increasing occurrence of impacts from 1920 onwards, for which possible factors are discussed. Further work is, however, needed to conclude on the respective contribution of the source effect, the increase in flood hazard, or the exposure of goods and people.
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Bolibar, J., Rabatel, A., Gouttevin, I., Zekollari, H., & Galiez, C. (2022). Nonlinear sensitivity of glacier mass balance to future climate change unveiled by deep learning. Nature Communications, 131(1).
Abstract: Glaciers and ice caps are experiencing strong mass losses worldwide, challenging water availability, hydropower generation, and ecosystems. Here, we perform the first-ever glacier evolution projections based on deep learning by modelling the 21st century glacier evolution in the French Alps. By the end of the century, we predict a glacier volume loss between 75 and 88%. Deep learning captures a nonlinear response of glaciers to air temperature and precipitation, improving the representation of extreme mass balance rates compared to linear statistical and temperature-index models. Our results confirm an over-sensitivity of temperature-index models, often used by large-scale studies, to future warming. We argue that such models can be suitable for steep mountain glaciers. However, glacier projections under low-emission scenarios and the behaviour of flatter glaciers and ice caps are likely to be biased by mass balance models with linear sensitivities, introducing long-term biases in sea-level rise and water resources projections. Deep learning unveils a nonlinear sensitivity of glacier mass changes to future climate warming, with important implications for water resources and sea-level rise coming from glaciers and particularly ice caps.
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Bonino, G., Iovino, D., Brodeau, L., & Masina, S. (2022). The Bulk Parameterizations Of Turbulent Air-Sea Fluxes In Nemo4: The Origin Of Sea Surface Temperature Differences In A Global Model Study. Geoscientific Model Development, 151(171), 6873–6889.
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Borlaza, L., Uzu, G., Ouidir, M., Lyon-Caen, S., Marsal, A., Weber, S., et al. (2022). Personal Exposure To Pm2.5 Oxidative Potential And Its Association To Birth Outcomes. Journal Of Exposure Science And Environmental Epidemiology, .
Abstract: Background: Prenatal Exposure To Fine Particulate Matter (Pm2.5) Assessed Through Its Mass Concentration Has Been Associated With Foetal Growth Restriction In Studies Based On Outdoor Levels. Oxidative Potential Of Pm2.5 (Op) Is An Emerging Metric A Priori Relevant To Mechanisms Of Action Of Pm On Health, With Very Limited Evidence To Indicate Its Role On Birth Outcomes. Objectives: We Investigated The Association Of Op With Birth Outcomes And Compared It With That Of Pm2.5 Mass Concentration. Methods: 405 Pregnant Women From Sepages Cohort (Grenoble Area) Carried Pm2.5 Personal Dosimeters For One Or Two One-Week Periods. Op Was Measured Using Dithiothreitol (Dtt) And Ascorbic Acid (Aa) Assays From The Collected Filters. Associations Of Each Exposure Metric With Offspring Weight, Height, And Head Circumference At Birth Were Estimated Adjusting For Potential Confounders. Results: The Correlation Between Pm2.5 Mass Concentration And Opvdtt Was 0.7. An Interquartile Range Increase In – Was Associated With Reduced Weight (Adjusted Change, -64 G, -166 To -11, P = 0.02) And Height (-4 Mm, -6 To -1, P = 0.01) At Birth. Pm2.5 Mass Concentration Showed Similar Associations With Weight (-53 G, -99 To -8, P = 0.02) And Height (-2 Mm, -5 To 0, P = 0.05). In Birth Height Models Mutually Adjusted For The Two Exposure Metrics, The Association With Opvdtt Was Less Attenuated Than That With Mass Concentration, While For Weight Both Effect Sizes Attenuated Similarly. There Was No Clear Evidence Of Associations With Head Circumference For Any Metric, Nor For Opvaa With Any Growth Parameter. Impact: Pm2.5 Pregnancy Exposure Assessed From Personal Dosimeters Was Associated With Altered Foetal Growth. Personal Op Exposure Was Associated With Foetal Growth Restrictions, Specifically Decreased Weight And Height At Birth, Possibly To A Larger Extent Than Pm2.5 Mass Concentration Alone. These Results Support Op Assessed From Dtt As Being A Health-Relevant Metric. Larger Scale Cohort Studies Are Recommended To Support Our Findings.
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Borlaza, L. J., Weber, S., Marsal, A., Uzu, G., Jacob, V., Besombes, J. L., et al. (2022). Nine-Year Trends Of Pm10 Sources And Oxidative Potential In A Rural background site in France. Atmospheric Chemistry And Physics, 222(131), 8701–8723.
Abstract: Long-term monitoring at sites with relatively low particulate pollution could provide an opportunity to identify changes in pollutant concentration and potential effects of current air quality policies. In this study, 9-year sampling of PM10 (particles with an aerodynamic diameter below 10 μm) was performed in a rural background site in France (Observatoire Menne de l'Environnement or OPE) from 28 February 2012 to 22 December 2020. The positive matrix factorization (PMF) method was used to apportion sources of PME) based on quantified chemical constituents and specific chemical tracers analysed on collected filters. Oxidative potential (OP), an emerging health metric that measures PM capability to potentially cause anti-oxidant imbalance in the lung, was also measured using two acellular assays: dithiothreitol (DTT) and ascorbic acid (AA). The sources of OP were also estimated using multiple linear regression (MLR) analysis. In terms of mass contribution, the dominant sources are secondary aerosols (nitrate- and sulfate-rich) associated with long-range transport (LRT). However, in terms of OP contributions, the main drivers are traffic, mineral dust, and biomass burning factors. There is also some OP contribution apportioned to the sulfate- and nitrate-rich sources influenced by processes and ageing during LRT that could have encouraged mixing with other anthropogenic sources. The study indicates much lower OP values than in urban areas. A substantial decrease (58 % reduction from the year 2012 to 2020) in the mass contributions from the traffic factor was found, even though this is not clearly reflected in its OP contribution. Nevertheless, the findings in this long-term study at the OPE site could indicate effectiveness of implemented emission control policies, as also seen in other long-term studies conducted in Europe, mainly for urban areas.
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Box, J. E., Wehrle, A., van As, D., Fausto, R. S., Kjeldsen, K. K., Dachauer, A., et al. (2022). Greenland Ice Sheet Rainfall, Heat And Albedo Feedback Impacts From The Mid-August 2021 Atmospheric River. Geophysical Research Letters, 494(111).
Abstract: Rainfall at the Greenland ice sheet Summit 14 August 2021, was delivered by an atmospheric river (AR). Extreme surface ablation expanded the all-Greenland bare ice area to near-record-high with snowline climbing up to 788 +/- 90 m. Ice sheet wet snow extent reached 46%, a record high for the 15-31 August AMSR data since 2003. Heat-driven firn deflation averaged 0.14 +/- 0.05 m at four accumulation area automatic weather stations (AWSs). Energy budget calculations from AWS data indicate that surface heating from rainfall is much smaller than from either the sensible, latent, net-longwave or solar energy fluxes. Sensitivity tests show that without the heat-driven snow-darkening, melt at 1,840 m would have totaled 28% less. Similarly, at 1,270 m elevation, without the bare ice exposure, melting would have been 51% less. Proglacial river discharge was the highest on record since 2006 for late August and confirms the melt-sustaining effect of the albedo feedback.
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Brighty, A., Jacob, V., Uzu, G., Borlaza, L., Conil, S., Hueglin, C., et al. (2022). Cellulose In Atmospheric Particulate Matter At Rural And Urban Sites across France and Switzerland. Atmospheric Chemistry And Physics, 222(9), 6021–6043.
Abstract: The spatiotemporal variations in free-cellulose concentrations in atmospheric particles, as a proxy for plant debris, were investigated using an improved protocol with a high-performance liquid chromatography with pulsed amperometric detection (HPLC-PAD) method. Filter samples were taken from nine sites of varying characteristics across France and Switzerland, with sampling covering all seasons. Concentrations of cellulose, as well as carbonaceous aerosol and other source-specific chemical tracers (e.g. elemental carbon, EC; levoglucosan; polyols; trace metals; and glucose), were quantified. Annual mean free-cellulose concentrations within PM10 (particulate matter) ranged from 29 +/- 38 ng m(-3) at Basel (urban site) to 284 +/- 225 ng m(-3) at Payerne (rural site). Concentrations were considerably higher during episodes, with spikes exceeding 1150 and 2200 ng m(-3) at Payerne and ANDRA-OPE (Agence nationale pour la gestion des dechets radioactifs Observatoire Perenne de l'Environnement; rural site), respectively. A clear seasonality, with highest cellulose concentrations during summer and autumn, was observed at all rural and some urban sites. However, some urban locations exhibited a weakened seasonality. Contributions of cellulose carbon to total organic carbon are moderate on average (0.7 %-5.9 %) but much greater during “episodes”, reaching close to 20 % at Payerne. Cellulose concentrations correlated poorly between sites, even at ranges of about 10 km, indicating the localised nature of the sources of atmospheric plant debris. With regards to these sources, correlations between cellulose and typical biogenic chemical tracers (polyols and glucose) were moderate to strong (R-s = 0.28-0.78, p < 0.0001) across the nine sites. Seasonality was strongest at sites with stronger biogenic correlations, suggesting the main source of cellulose arises from biogenic origins. A second input to ambient plant debris concentrations was suggested via resuspension of plant matter at several urban sites, due to moderate cellulose correlations with mineral dust tracers, Ca2+, and Ti metal (R-s = 0.28-0.45, p < 0.007). No correlation was obtained with the biomass burning tracer (levoglucosan), an indication that this is not a source of atmospheric cellulose. Finally, an investigation into the interannual variability in atmospheric cellulose across the Grenoble metropole was completed. It was shown that concentrations and sources of ambient cellulose can vary considerably between years. All together, these results deeply improve our knowledge on the phenomenology of plant debris within ambient air.
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Burgard, C., Jourdain, N., Reese, R., Jenkins, A., & Mathiot, P. (2022). An Assessment Of Basal Melt Parameterisations For Antarctic Ice Shelves. Cryosphere, 161(121), 4931–4975.
Abstract: Ocean-Induced Ice-Shelf Melt Is One Of The Largest Uncertainty Factors In The Antarctic Contribution To Future Sea-Level Rise. Several Parameterisations Exist, Linking Oceanic Properties In Front Of The Ice Shelf To Melt At The Base Of The Ice Shelf, To Force Ice-Sheet Models. Here, We Assess The Potential Of A Range Of These Existing Basal Melt Parameterisations To Emulate Basal Melt Rates Simulated By A Cavity-Resolving Ocean Model On The Circum-Antarctic Scale. To Do So, We Perform Two Cross-Validations, Over Time And Over Ice Shelves Respectively, And Re-Tune The Parameterisations In A Perfect-Model Approach, To Compare The Melt Rates Produced By The Newly Tuned Parameterisations To The Melt Rates Simulated By The Ocean Model. We Find That The Quadratic Dependence Of Melt To Thermal Forcing Without Dependency On The Individual Ice-Shelf Slope And The Plume Parameterisation Yield The Best Compromise, In Terms Of Integrated Shelf Melt And Spatial Patterns. The Box Parameterisation, Which Separates The Sub-Shelf Circulation Into Boxes, The Picop Parameterisation, Which Combines The Box And Plume Parameterisation, And Quadratic Parameterisations With Dependency On The Ice Slope Yield Basal Melt Rates Further From The Model Reference. The Linear Parameterisation Cannot Be Recommended As The Resulting Integrated Ice-Shelf Melt Is Comparably Furthest From The Reference. When Using Offshore Hydrographic Input Fields In Comparison To Properties On The Continental Shelf, All Parameterisations Perform Worse; However, The Box And The Slope-Dependent Quadratic Parameterisations Yield The Comparably Best Results. In Addition To The New Tuning, We Provide Uncertainty Estimates For The Tuned Parameters.
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Cabrera, M., Moulatlet, G., Valencia, B., Maisincho, L., Rodriguez-Barroso, R., Albendin, G., et al. (2022). Microplastics in a tropical Andean Glacier: A transportation process across the Amazon basin? Science Of The Total Environment, 805.
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Calonne, N., Burr, A., Philip, A., Flin, F., & Geindreau, C. (2022). Effective coefficient of diffusion and permeability of firn at Dome C and Lock In, Antarctica, and of various snow types – estimates over the 100-850 kg m(-3) density range. Cryosphere, 161(3), 967–980.
Abstract: Modeling air transport through the entire firn column of polar ice sheets is needed to interpret climate archives. To this end, different regressions have been proposed in the past to estimate the effective coefficient of diffusion and permeability of firn. These regressions are often valid for specific depth or porosity ranges only. Also, they constitute a source of uncertainty as evaluations have been limited by the lack of reliable data of firn transport properties. To contribute with a new dataset, this study presents the effective coefficient of diffusion and the permeability at Dome C and Lock In, Antarctica, from the near-surface to the close-off (23 to 133 m depth). Also, microstructure is characterized based on density, specific surface area, closed porosity ratio, connectivity index, and structural anisotropy through the correlation lengths. All properties were estimated based on pore-scale computations from 3D tomographic images of firn samples. The normalized diffusion coefficient ranges from 1.9 x 10(-1) to 8.3 x 10(-5) , and permeability ranges from 1.2 x 10(-9) to 1.1 x 10(-12) m(2), for densities between 565 and 888 kg m(-3). No or little anisotropy is reported. Next, we investigate the relationship of the transport properties with density over the firn density range (550-850 kg m(-3)), as well as over the entire density range encountered in the ice sheets (100-850 kg m(-3)), by extending the datasets with transport properties of alpine and artificial snow from previous studies. Classical analytical models and regressions from literature are evaluated against the estimates from pore-scale simulations. For firn, good agreements are found for permeability and the diffusion coefficient with two existing regressions of the literature based on open porosity despite the rather different site conditions (Greenland). Over the entire 100-850 kg m(-3) density range, permeability is accurately reproduced by the Carman-Kozeny and self-consistent (spherical bi-composite) models when expressed in terms of a rescaled porosity, phi(res) = (phi – phi(off)) – (1 – phi(off)), to account for pore clo- sure, where q5off is the close-off porosity. For the normalized diffusion coefficient, none of the evaluated formulas were satisfactory, so we propose a new regression based on the rescaled porosity that reads D / D-air = (phi(res))(1.61).
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Camara, M., Diba, I., & Diedhiou, A. (2022). Effects of Land Cover Changes on Compound Extremes over West Africa Using the Regional Climate Model RegCM4. Atmosphere, 131(3).
Abstract: This study aims to characterize the impacts of the Sahel-Sahara interface reforestation on compound extremes in the Sahel region during the West African monsoon season (June-July-August-September, JJAS). For this purpose, we performed a simulation with the standard version of the RegCM4 model, and another simulation with the altered version of the same model, taking into account the incorporated forest. Results show that reforestation may strongly influence the frequency of individual extreme events (dry and warm days) by decreasing them over and off the reforested zone. The reduction in these extreme dry and warm days may be due partly to the strengthening of the atmospheric moisture content over most parts of the West African domain and the weakening of the sensible heat flux south of 16 degrees N. The analysis also shows an increase in extreme wet days over and off the reforested zone, which could be associated partly with the strengthening of evapotranspiration over most parts of the West African domain, including the reforested area. The analysis of compound extremes shows a strong occurrence of the compound dry/warm mode over the northern Sahel for both runs, probably due to the weak precipitation recorded in this zone. Both experiments also simulated a strong compound wet/warm mode occurrence over the Sahel due to a high rainfall occurrence over this region. When comparing both runs, the impact of the reforestation was to decrease (increase) the compound extreme dry/warm (wet/warm) mode over the reforested zone. The dry/warm mode decrease is consistent with that of individual extreme dry and warm days, while the compound wet/warm mode increase may be driven by that of the extreme wet days. Finally, when considering the seasonal cycle, the dry/warm mode exhibits a more substantial decrease in the beginning (June-July, JJ) than during the peak of the West African summer monsoon season (August-September, AS). Moreover, reforestation similarly affects the compound wet/warm mode in JJ and AS by increasing it in the reforested region and decreasing it over the Southern Sahel (south of 15 degrees N). This work suggests that reforestation may be a good solution for West African policymakers to mitigate climate change over the region and to develop better strategies for water resource management.
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Cao, Y., Jiang, Z., Alexander, B., Cole-Dai, J., Savarino, J., Erbland, J., et al. (2022). On The Potential Fingerprint Of The Antarctic Ozone Hole In Ice-Core Nitrate Isotopes: A Case Study Based On A South Pole Ice Core. Atmospheric Chemistry And Physics, 222(202), 13407–13422.
Abstract: Column Ozone Variability Has Important Implications For Surface Photochemistry And The Climate. Ice-Core Nitrate Isotopes Are Suspected To Be Influenced By Column Ozone Variability And Delta N-15(No3-) Has Been Sought To Serve As A Proxy Of Column Ozone Variability. In This Study, We Examined The Ability Of Ice-Core Nitrate Isotopes To Reflect Column Ozone Variability By Measuring Delta N-15(No3-) And Delta O-17(No3-) In A Shallow Ice Core Drilled At The South Pole. The Ice Core Covers The Period 1944-2005, And During This Period Delta N-15(No3-) Showed Large Annual Variability ((59.2 +/- 29.3)Parts Per Thousand), But With No Apparent Response To The Antarctic Ozone Hole. Utilizing A Snow Photochemical Model, We Estimated 6.9 Parts Per Thousand Additional Enrichments In Delta N-15(No3-) Could Be Caused By The Development Of The Ozone Hole. Nevertheless, This Enrichment Is Small And Masked By The Effects Of The Snow Accumulation Rate At The South Pole Over The Same Period Of The Ozone Hole. The Delta O-17(No3-) Record Has Displayed A Decreasing Trend By Similar To 3.4 Parts Per Thousand Since 1976. This Magnitude Of Change Cannot Be Caused By Enhanced Post-Depositional Processing Related To The Ozone Hole. Instead, The Delta O-17(No3-) Decrease Was More Likely Due To The Proposed Decreases In The O-3 / Hox Ratio In The Extratropical Southern Hemisphere. Our Results Suggest Ice-Core Delta N-15(No3-) Is More Sensitive To Snow Accumulation Rate Than To Column Ozone, But At Sites With A Relatively Constant Snow Accumulation Rate, Information Of Column Ozone Variability Embedded In Delta N-15(No3-) Should Be Retrievable.
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Chagnaud, G., Panthou, G., Vischel, T., & Lebel, T. (2022). A synthetic view of rainfall intensification in the West African Sahel. Environmental Research Letters, 171(4).
Abstract: The West African Sahel has been facing for more than 30 years an increase in extreme rainfall with strong socio-economic impacts. This situation challenges decision-makers to define adaptation strategies in a rapidly changing climate. The present study proposes (i) a quantitative characterization of the trends in extreme rainfall at the regional scale, (ii) the translation of the trends into metrics that can be used by hydrological risk managers, (iii) elements for understanding the link between the climatology of extreme and mean rainfall. Based on a regional non-stationary statistical model applied to in-situ daily rainfall data over the period 1983-2015, we show that the region-wide increasing trend in extreme rainfall is highly significant. The change in extreme value distribution reflects an increase in both the mean and variability, producing a 5%/decade increase in extreme rainfall intensity whatever the return period. The statistical framework provides operational elements for revising the design methods of hydraulic structures which most often assume a stationary climate. Finally, the study shows that the increase in annual maxima of daily rainfall is more attributable to stronger storm intensities (80%) than to more frequent storm occurrences (20%), reflecting a major rainfall regime shift in comparison to those observed in the region since 1950.
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Chamarande, T., Mathy, S., & Hingray, B. (2022). The Least Cost Design Of 100 % Solar Power Microgrids In Africa: Sensitivity To Meteorological And Economic Drivers And Possibility For Simple Pre- Sizing Rules. Energy For Sustainable Development, 696, 211–223.
Abstract: Autonomous Micro-Grids Based On Solar Photovoltaic (Pv) Are One Of The Most Promising Solutions To Provide Electricity Access In Many Regions Worldwide. Different Storage/Pv Capacities Can Produce The Same Level Of Quality Service, But An Optimal Design Is Typically Identified To Minimize The Levelized Cost Of Electricity. This Cost Optimization However Relies On Technical And Economic Hypothesis That Come With Large Uncertainties And/Or Spatial Disparities. This Article Explores The Sensitivity Of The Optimal Sizing To Variations And Uncertainties Of Such Parameters. Using Data From Heliosat And Era5, We Simulate The Solar Pv Production And Identify The Least Cost Configurations For 200 Locations In Africa. Our Results Show That The Optimal Configuration Is Highly Dependent On The Characteristics Of The Resource, And Especially On Its Co-Variability Structure With The Electric Demand On Different Timescales. It Is Conversely Rather Insensitive To Cost Hypotheses, Which Allow Us To Propose Simple Pre-Sizing Rules Based On The Only Characteristics Of The Solar Resource And Electricity Demand. The Optimal Storage Capacity Can Be Estimated From The 75Th Percentile Of The Daily Nocturnal Demand And The Optimal Pv Capacity From The Mean Demand And The Standard Deviation Of The Daily Power Difference Between Solar Production And Demand. (C) 2022 International Energy Initiative. Published By Elsevier Inc. All Rights Reserved.
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Charrier, L., Yan, Y., Trouve, E., Koeniguer, E., Mouginot, J., & Millan, R. (2022). Fusion Of Multitemporal Multisensor Velocities Using Temporal Closure Of Fractions Of Displacements. Ieee Geoscience And Remote Sensing Letters, 191.
Abstract: Numerous Glacier Velocity Observations, Derived From Spaceborne Imagery, Are Available Online, But It Remains Difficult To Analyze Them Because They Are Measured With Different Temporal Baselines, By Various Sensors. In This Study, We Propose A Novel Formulation Of The Temporal Closure To Fuse Multitemporal Multisensor Velocity Observations Without Prior Information On The Displacement Behavior And The Data Uncertainty. We Establish A System Of Linear Equations Between Combinations Of Displacement Observations And Fractions Of Estimated Displacements. The Proposed Approach Provides A Velocity Time-Series With A Regular And Optimal Temporal Sampling, The Latter Representing A Compromise Between The Temporal Resolution And The Signal-To-Noise Ratio. The Proposed Approach Is First Evaluated On Synthetic Datasets And Second On Sentinel-2 And Venus Velocity Observations Over The Fox Glacier In New Zealand. The Results Show The Intra-Annual Variability Of Fox Glacier Surface Velocity With A Reduced Uncertainty And Complete Temporal Coverage.
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Charrondiere, C., Brun, C., Hopfinger, E. J., Cohard, J. M., & Sicart, J. E. (2022). Mean Flow Structure Of Katabatic Winds And Turbulent Mixing Properties. Journal Of Fluid Mechanics, 9419.
Abstract: The recent field measurements of katabatic winds on steep alpine slopes provide a unique database for theoretical analysis of the mean flow development and the determination of mixing properties. The theory is based on the depth-integrated momentum and heat equations, and demonstrates an increase in mean velocity U with downstream distance x according to x(n) (n <= 1/2). An equation for the mean wind velocity is established, expressing its dependency on the buoyancy flux, related to the heat flux to the ground, entrainment and bottom friction. No ambient stratification, and ambient wind and constant ground surface temperature, lead to U similar to x(1/2), while constant heat flux to the ground leads to U similar to x(1/3) and requires that the reduced gravity decreases as x(-1/3). Stable ambient stratification N causes, in addition to small-amplitude mean flow oscillations, a decrease in reduced gravity with x, in which case the assumption of constant surface heat flux along x is only an approximation. The turbulent fluxes are a function of gradient Richardson number Ri with the ratio of turbulent diffusivity to viscosity K-h/K-m changing from nearly 1.4 to approximately 0.5 at Ri approximate to 0.5. A new mixing efficiency is introduced that includes turbulence kinetic energy production or consumption by along-slope turbulent buoyancy flux. It increases with Ri up to 0.25 at Ri approximate to 0.5 and then remains nearly constant. The measurements allowed us to determine the bottom drag coefficients and interfacial entrainment, with the ground surface heat flux being determined from the mean buoyancy flux.
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Cheng, G., Morlighem, M., Mouginot, J., & Cheng, D. (2022). Helheim Glacier's Terminus Position Controls Its Seasonal and Inter-Annual Ice Flow Variability. Geophysical Research Letters, 494(5).
Abstract: Over the past decade, one of the largest contributors to total ice discharge across the Greenland ice sheet, Helheim Glacier, has experienced large fluctuations in ice velocity. In this study, we simulate the dynamics of Helheim, from 2007 to 2020, using the Ice-sheet and Sea-level System Model to identify the drivers of these large changes in ice discharge. By quantifying the impact of individual external forcing and model parameters on Helheim's modeled velocity, we find that the position of the calving front alone explains the dynamic variability of the glacier, as it has a direct and large impact on Helheim's ice velocity. The seasonal to inter-annual variability of Helheim Glacier is, however, relatively insensitive to the choice of friction law or ice rheology factor. This study shows that more research on calving dynamics and ice-ocean interactions is required to project the future of this sector of Greenland.
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Chmiel, M., Godano, M., Piantini, M., Brigode, P., Gimbert, F., Bakker, M., et al. (2022). Brief Communication: Seismological Analysis Of Flood Dynamics And hydrologically triggered earthquake swarms associated with Storm Alex. Natural Hazards And Earth System Sciences, 222(5), 1541–1558.
Abstract: On 2 October 2020, the Maritime Alps in southern France were struck by the devastating Storm Alex, which caused locally more than 600 mm of rain in less than 24 h. The extreme rainfall and flooding destroyed regional rain and stream gauges. That hinders our understanding of the spatial and temporal dynamics of rainfall-runoff processes during the storm. Here, we show that seismological observations from permanent seismic stations constrain these processes at a catchment scale. The analysis of seismic power, peak frequency, and the back azimuth provides us with the timing and velocity of the propagation of flash-flood waves associated with bedload-dominated phases of the flood on the Vesubie River. Moreover, the combined short-term average to long-term average ratio and template-matching earthquake detection reveal that 114 local earthquakes between local magnitude M-L = -0.5 and M-L = 2 were triggered by the hydrological loading and/or the resulting in situ underground pore pressure increase. This study shows the impact of Storm Alex on the Earth's surface and deep-layer processes and paves the way for future works that can reveal further details of these processes.
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Colliander, A., Reichle, R., Crow, W., Cosh, M., Chen, F., Chan, S., et al. (2022). Validation of Soil Moisture Data Products From the NASA SMAP Mission. Ieee Journal Of Selected Topics In Applied Earth Observations And Remote Sensing, 15, 364–392.
Abstract: The National Aeronautics and Space Administration Soil Moisture Active Passive (SMAP) mission has been validating its soil moisture (SM) products since the start of data production on March 31, 2015. Prior to launch, the mission defined a set of criteria for core validation sites (CVS) that enable the testing of the key mission SM accuracy requirement (unbiased root-mean-square error <0.04 m(3)/m(3)). The validation approach also includes other (“sparse network”) in situ SM measurements, satellite SM products, model-based SM products, and field experiments. Over the past six years, the SMAP SM products have been analyzed with respect to these reference data, and the analysis approaches themselves have been scrutinized in an effort to best understand the products' performance. Validation of the most recent SMAP Level 2 and 3 SM retrieval products (R17000) shows that the L-band (1.4 GHz) radiometer-based SM record continues to meet mission requirements. The products are generally consistent with SM retrievals from the European Space Agency Soil Moisture Ocean Salinity mission, although there are differences in some regions. The high-resolution (3-km) SM retrieval product, generated by combining Copernicus Sentinel-1 data with SMAP observations, performs within expectations. Currently, however, there is limited availability of 3-km CVS data to support extensive validation at this spatial scale. The most recent (version 5) SMAP Level 4 SM data assimilation product providing surface and root-zone SM with complete spatio-temporal coverage at 9-km resolution also meets performance requirements. The SMAP SM validation program will continue throughout the mission life; future plans include expanding it to forested and high-latitude regions.
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Collow, A. B. M., Shields, C. A., Guan, B., Kim, S., Lora, J. M., McClenny, E. E., et al. (2022). An Overview Of Artmip'S Tier 2 Reanalysis Intercomparison: Uncertainty in the Detection of Atmospheric Rivers and Their Associated Precipitation. Journal Of Geophysical Research-Atmospheres, 1271(8).
Abstract: Atmospheric rivers, or long but narrow regions of enhanced water vapor transport, are an important component of the hydrologic cycle as they are responsible for much of the poleward transport of water vapor and result in precipitation, sometimes extreme in intensity. Despite their importance, much uncertainty remains in the detection of atmospheric rivers in large datasets such as reanalyses and century scale climate simulations. To understand this uncertainty, the Atmospheric River Tracking Method Intercomparison Project (ARTMIP) developed tiered experiments, including the Tier 2 Reanalysis Intercomparison that is presented here. Eleven detection algorithms submitted hourly tags--binary fields indicating the presence or absence of atmospheric rivers--of detected atmospheric rivers in the Modern Era Retrospective Analysis for Research and Applications, version 2 (MERRA-2) and European Centre for Medium-Range Weather Forecasts' Reanalysis Version 5 (ERA5) as well as six-hourly tags in the Japanese 55-year Reanalysis (JRA-55). Due to a higher climatological mean for integrated water vapor transport in MERRA-2, atmospheric rivers were detected more frequently relative to the other two reanalyses, particularly in algorithms that use a fixed threshold for water vapor transport. The finer horizontal resolution of ERA5 resulted in narrower atmospheric rivers and an ability to detect atmospheric rivers along resolved coastlines. The fraction of hemispheric area covered by ARs varies throughout the year in all three reanalyses, with different atmospheric river detection tools having different seasonal cycles.
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Conway, J., Abermann, J., Andreassen, L., Azam, M., Cullen, N., Fitzpatrick, N., et al. (2022). Cloud Forcing Of Surface Energy Balance From In Situ Measurements In Diverse Mountain Glacier Environments. Cryosphere, 161(8), 3331–3356.
Abstract: Clouds Are An Important Component Of The Climate System, Yet Our Understanding Of How They Directly And Indirectly Affect Glacier Melt In Different Climates Is Incomplete. Here We Analyse High-Quality Datasets From 16 Mountain Glaciers In Diverse Climates Around The Globe To Better Understand How Relationships Between Clouds And Near-Surface Meteorology, Radiation And Surface Energy Balance Vary. The Seasonal Cycle Of Cloud Frequency Varies Markedly Between Mountain Glacier Sites. During The Main Melt Season At Each Site, An Increase In Cloud Cover Is Associated With Increased Vapour Pressure And Relative Humidity, But Relationships To Wind Speed Are Site Specific. At Colder Sites (Average Near-Surface Air Temperature In The Melt Season <0 Degrees C), Air Temperature Generally Increases With Increasing Cloudiness, While For Warmer Sites (Average Near-Surface Air Temperature In The Melt Season >> 0 Degrees C), Air Temperature Decreases With Increasing Cloudiness. At All Sites, Surface Melt Is More Frequent In Cloudy Compared To Clear-Sky Conditions. The Proportion Of Melt From Temperature-Dependent Energy Fluxes (Incoming Longwave Radiation, Turbulent Sensible Heat And Latent Heat) Also Universally Increases In Cloudy Conditions. However, Cloud Cover Does Not Affect Daily Total Melt In A Universal Way, With Some Sites Showing Increased Melt Energy During Cloudy Conditions And Others Decreased Melt Energy. The Complex Association Of Clouds With Melt Energy Is Not Amenable To Simple Relationships Due To Many Interacting Physical Processes (Direct Radiative Forcing; Surface Albedo; And Co-Variance With Temperature, Humidity And Wind) But Is Most Closely Related To The Effect Of Clouds On Net Radiation. These Results Motivate The Use Of Physics-Based Surface Energy Balance Models For Representing Glacier-Climate Relationships In Regional- And Global-Scale Assessments Of Glacier Response To Climate Change.
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Creutin, J. D., Blanchet, J., Reverdy, A., Brochet, A., Lutoff, C., & Robert, Y. (2022). Reported Occurrence of Multiscale Flooding in an Alpine Conurbation over the Long Run (1850-2019). Water, 141(4).
Abstract: This paper deals with the identification of extreme multiscale flooding events in the Alpine conurbation of Grenoble, France. During such events, typically over one to several days, the organization in space and time of the generating hydrometeorological situation triggers the concurrent reaction of varied sets of torrents and main rivers and creates diverse socioeconomic damages and disruptions. Given the limits of instrumental data over the long run, in particular at the torrent scale, we explore the potential of a database of reported extreme flood events to study multiscale flooding over a Metropolitan domain. The definition of Metropolitan events is mainly based on the database built by the RTM (Restauration des Terrains de Montagne, a technical service of the French Forest Administration). Relying on expert reports, the RTM database covers the long lifetime of this French national service for the management of mountainous areas (1850-2019). It provides quantitative information about the time and place of inundation events as well as qualitative information about the generating phenomena and the consequent damages. The selection process to define Metropolitan events simply chronologically explores the RTM database and complements it with historical research data. It looks for concurrence between site events at the same date under a chosen set of criteria. All scales together, we selected 104 Metropolitan events between 1850 and 2019. Exploring the list of dates, we examine the homogeneity of the Metropolitan events over 1850-2019 and their space-time characteristics. We evidence the existence of multiscale flooding at the Metropolitan scale, and we discuss some implications for flood risk management.
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Crotti, I., Quiquet, A., Landais, A., Stenni, B., Wilson, D., Severi, M., et al. (2022). Wilkes Subglacial Basin Ice Sheet Response To Southern Ocean Warming During Late Pleistocene Interglacials. Nature Communications, 131(1).
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Danso, D. K., Anquetin, S., Diedhiou, A., Lavaysse, C., Hingray, B., Raynaud, D., et al. (2022). A CMIP6 assessment of the potential climate change impacts on solar photovoltaic energy and its atmospheric drivers in West Africa. Environmental Research Letters, 171(4).
Abstract: Many solar photovoltaic (PV) energy projects are currently being planned and/or developed in West Africa to sustainably bridge the increasing gap between electricity demand and supply. However, climate change will likely affect solar power generation and the atmospheric factors that control it. For the first time, the state-of-the-art CMIP climate models (CMIP6) are used to investigate the potential future evolution of solar power generation and its main atmospheric drivers in West Africa. A multi-model analyses carried out revealed a decrease of solar PV potential throughout West Africa in the 21st century, with an ensemble mean reduction reaching about 12% in southern parts of the region. In addition, the variability of future solar PV production is expected to increase with a higher frequency of lower production periods. The projected changes in the solar PV production and its variability are expected to be predominant in the June to August season. We found the decrease in the solar PV potential to be driven by a decrease of surface irradiance and an increase of near-surface air temperature. However, the decrease of the surface irradiance accounted for a substantially larger percentage of the projected solar PV potential. The decrease in surface irradiance was further linked to changes in both cloud cover and aerosol presence, although generally much more strongly for the former.
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Dao, T. S., Nguyen, V. T., Baduel, C., Bui, M. H., Tran, V. T., Pham, T. L., et al. (2022). Toxicity of di-2-ethylhexyl phthalate and tris (2-butoxyethyl) phosphate to a tropical micro-crustacean (Ceriodaphnia cornuta) is higher in Mekong River water than in standard laboratory medium. Environmental Science And Pollution Research, .
Abstract: Plasticizers such as di(2-ethylhexyl) phthalate (DEHP) and tris (2-butoxyethyl) phosphate (TBOEP) are manufactured chemicals produced in high volumes. These chemicals are frequently detected in the aquatic environment and cause toxic effects on organisms. In this study, we assessed the chronic impacts of DEHP and TBOEP, respectively, at the concentration of 100 μL-1 dissolved in the artificial medium (M4/4) and Mekong River water on life history traits of a tropical micro-crustacean, Ceriodaphnia cornuta, for 14 days. DEHP and TBOEP substantially reduced the survival of C. cornuta. In M4/4 medium, both plasticizers strongly enhanced reproduction but did not influence the growth of C. cornuta. Mekong River water, plasticizers-exposed C. cornuta produced less neonates than those in the control. The detrimental impacts of DEHP and TBOEP on the fitness of C. cornuta were much stronger in natural river water than in M4/4. Our results suggest that plasticizers can cause adverse effects on tropical freshwater cladocerans, particularly in natural water. These results are of a deep concern, as national and international regulatory guidelines which are based on ecotoxicological tests using standard media may not fully capture these effects.
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Dasari, S., & Widory, D. (2022). Radiocarbon (C-14) Analysis Of Carbonaceous Aerosols: Revisiting The Existing Analytical Techniques for Isolation of Black Carbon. Frontiers In Environmental Science, 101.
Abstract: Air pollution, a complex cocktail of different components, exerts an influence on climate/human; health both locally and away from source regions. The issue of air pollution is often closely linked; to carbonaceous aerosols, the assessment of climate/air quality/health impact of which remains associated with large uncertainties. Black carbon (BC)-a product of incomplete combustion-is a potent climate warming agent and one of the central components to this issue. An accurate; knowledge of BC emitting sources is necessary for devising appropriate mitigation strategies and; policies to reduce the associated climate/environmental burden. The radiocarbon isotope (C-14 or carbon-14) fingerprinting allows for an unambiguous and quantitative constraining of the BC sources and is therefore a well-popularized method. Here, we review the existing analytical techniques for the isolation of BC from a filter matrix for conducting C-14-based investigations. This work summarizes the protocols in use, provides an overarching perspective on the state-of- the-art and recommendations for certain aspects of future method development.
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Dasari, S., Paris, G., Saar, B., Pei, Q. M., Cong, Z. Y., & Widory, D. (2022). Sulfur Isotope Anomalies (Delta S-33) In Urban Air Pollution Linked To Mineral-Dust-Associated Sulfate. Environmental Science & Technology Letters, .
Abstract: Sulfur isotope analysis provides a unique probe for source-specific information and certain atmospheric reactions. Globally, atmospheric aerosols in urban locations exhibit significant sulfur mass-independent fractionation (i.e., S-MIF, Delta S-33 not equal 0). The origin(s) of these S-MIF anomalies remains unclear, thereby limiting the interpretation and/or application of such signals. Her; we conducted dual-isotope (Delta S-33 and delta S-34) fingerprinting of sulfate aerosols from summertime megacity Delhi in south Asia. A shift toward concomitantly high Delta S-33 (from 0.2 parts per thousand to 0.5 parts per thousand) and low delta S-34 (from 5 parts per thousand to 1 parts per thousand) values was observed with the influx of mineral dust. The Fe:Al ratio showed significant correlations with both sulfate loadings (R-2 = 0.84) and Delta S-33 signatures (R-2 = 0.77). Contrary to the prevailing paradigm, this observational evidence suggests that mineral-dust-associated sulfate exhibits S-MIF anomalies. Atmospheric processing of mineral dust plausibly leads to the production of these anomalies. Our evaluation suggests that an inherent mechanism(s) remains elusive. Although hindered by end-member uncertainties, we show that S-MIF signals can be source apportioned to quantitatively constrain the fraction of mineral-dust-associated sulfate in urban locations. The influx of mineral-dust-associated sulfate can influence urban air pollution affecting air quality and/or human health and as such requires monitoring. Urban Delta S-33 signals can therefore be used to trace this sulfate fraction, thereby improving our understanding of sulfate aerosol dynamics.
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de Lavenne, A., Andreassian, V., Crochemore, L., Lindstrom, G., & Arheimer, B. (2022). Quantifying Multi-Year Hydrological Memory With Catchment Forgetting Curves. Hydrology And Earth System Sciences, 262(101), 2715–2732.
Abstract: A climatic anomaly can potentially affect the hydrological behaviour of a catchment for several years. This article presents a new approach to quantifying this multi-year hydrological memory, using exclusively streamflow and climate data. Rather than providing a single value of catchment memory, we aim to describe how this memory fades over time. The precipitation-runoff relationship is analyzed through the concept of elasticity. Elasticity quantifies the change in one quantity caused by the change in another quantity. We analyze the elasticity of the relation between the annual anomalies of runoff yield and humidity index. We identify Catchment Forgetting Curves (CFC) to quantify multiyear catchment memory, considering not only the current year's humidity anomaly but also the anomalies of the preceding years. The variability of CFCs is investigated on a set of 158 Swedish and 527 French catchments. As expected, French catchments overlying large aquifers exhibit a long memory, i.e., with the impact of climate anomalies detected over several years. In Sweden, the expected effect of the lakes is less clear. For both countries, a relatively strong relationship between the humidity index and memory is identified, with drier regions exhibiting longer memory. Taking into account the multi-year memory has significantly improved the elasticity analysis for 15 % of the catchments. Our work thus underlines the need to account for catchment memory in order to produce meaningful and geographically coherent elasticity indices.
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Delrieu, G., Khanal, A. K., Cazenave, F., & Boudevillain, B. (2022). Sensitivity Analysis Of Attenuation In Convective Rainfall At X-Band frequency using the mountain reference technique. Atmospheric Measurement Techniques, 151(111), 3297–3314.
Abstract: The RadAlp experiment aims at improving quantitative precipitation estimation (QPE) in the Alps thanks to X-band polarimetric radars and in situ measurements deployed in the region of Grenoble, France. In this article, we revisit the physics of propagation and attenuation of microwaves in rain. We first derive four attenuation-reflectivity (AZ) algorithms constrained, or not, by path-integrated attenuations (PIAs) estimated from the decrease in the return of selected mountain targets when it rains compared to their dry weather levels (the so-called mountain reference technique – MRT). We also consider one simple polarimetric algorithm based on the profile of the total differential phase shift between the radar and the mountain targets. The central idea of the work is to implement these five algorithms all together in the framework of a generalized sensitivity analysis in order to establish useful parameterizations for attenuation correction. The parameter structure and the inherent mathematical ambiguity of the system of equations makes it necessary to organize the optimization procedure in a nested way. The core of the procedure consists of (i) exploring with classical sampling techniques the space of the parameters allowed to be variable from one target to the other and from one time step to the next, (ii) computing a cost function (CF) quantifying the proximity of the simulated profiles and (iii) selecting parameters sets for which a given CF threshold is exceeded. This core is activated for a series of values of parameters supposed to be fixed, e.g., the radar calibration error for a given event. The sensitivity analysis is performed for a set of three convective events using the 0 degrees elevation plan position indicator (PPI) measurements of the Meteo-France weather radar located on top of the Moucherotte mountain (altitude of 1901 ma.s.l. – above sea level). It allows the estimation of critical parameters for radar QPE using radar data alone. In addition to the radar calibration error, this includes the time series of radome attenuation and estimations of the coefficients of the power law models relating the specific attenuation and the reflectivity (A-Z relationship) on the one hand and the specific attenuation and the specific differential phase shift (A-K-dp relationship) on the other hand. It is noteworthy that the A-Z and A-K-dp relationships obtained are consistent with those derived from concomitant drop size distribution measurements at ground level, in particular with a slightly non-linear A-K-dp relationship (A = 0:28 K-dp(1.1)). X-Band radome attenuations as high as 15 dB were estimated, leading to the recommendation of avoiding the use of radomes for remote sensing of precipitation at such a frequency.
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Dewar, W., Parfitt, R., & Wienders, N. (2022). Routine Reversal Of The Amoc In An Ocean Model Ensemble. Geophysical Research Letters, 494(242).
Abstract: We Describe A Form Of Atlantic Meridional Overturning Circulation (Amoc) Variability That We Believe Has Not Previously Appeared In Observations Or Models. It Is Found In An Ensemble Of Eddy-Resolving North Atlantic Simulations That The Amoc Frequently Reverses In Sign At Similar To 35 Degrees N With Gyre-Wide Anomalies In Size And That Reach Throughout The Water Column. The Duration Of Each Reversal Is Roughly 1 Month. The Reversals Are Part Of The Annual Amoc Cycle Occurring In Boreal Winter, Although Not All Years Feature An Actual Reversal In Sign. The Occurrence Of The Reversals Appears In Our Ensemble Mean, Suggesting It Is A Forced Feature Of The Circulation. A Partial Explanation Is Found In An Ekman Response To Wind Stress Anomalies. Model Ensemble Simulations Run With Different Combinations Of Climatological And Realistic Forcings Argue That It Is The Atmospheric Forcing Specifically That Results In The Reversals, Despite The Signals Extending Into The Deep Ocean.
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Diba, I., Diedhiou, A., Famien, A., Camara, M., & Fotso-Nguemo, T. (2022). Changes In Compound Extremes Of Rainfall And Temperature Over West Africa Using Cmip5 Simulations. Environmental Research Communications, 4(101).
Abstract: This Study Aims To Characterize Changes In Compound Extremes Of Rainfall And Temperature Over West Africa. For This Purpose, Data From Chirps Observations, The Era5 Reanalysis, And Twenty-Four (24) Climate Models Involved In The Cmip5 Project Were Analyzed. First, Climate Models Were Evaluated In Terms Of Their Capacity To Simulate Summer Mean Climatology And Compound Extremes During The Historical Period (1981-2005), And Secondly, Changes In Compound Extremes Were Examined Under Rcp8.5 Emission Scenario Between The Near Future (2031-2055) And The Far Future (2071-2095) Relative To The Historical Period. Despite The Presence Of Some Biases, The Ensemble Mean Of The Models Well Reproduces The Compound Extremes Patterns Over West Africa At The Seasonal And Intraseasonal Timescales. The Analysis Over The Historical Period With Chirps/Era5 Dataset Shows A Strong Occurrence Of The Dry/Warm Mode Over The Northern Sahel During The June-July-August-September Period (Jjas; Main Rainy Season) And Over The Guinean Region During The February-March-April-May Season (Fmam; First And Main Rainy Season). These Strong Occurrences Are Due To A Weak And Highly Frequent Precipitation Recorded In These Zones. The Compound Wet/Warm Mode Is Frequent In Jjas Over The Sahel And The Sudanian Zone (Transition Area Between Sahel And Guinean Regions), While In Fmam, Its Occurrence Is Maximum Over The Guinean Region. The Study Also Shows That The Dry/Warm Mode Will Increase In The Whole Sahel (Western And Central) And In The Guinean Zone In The Near And Far Futures While The Compound Wet/Warm Mode Will Decrease In The Whole Region. This Study Suggests That The West Africa Region Will Be Prone To Drought Intensified By Warmer Temperatures And Calls For Climate Action And Adaptation Strategies To Mitigate The Risks On Rain-Fed Agriculture, Energy, And On Animals And Human Health.
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Dietz, R., Wilson, S., Loseto, L. L., Dommergue, A., Xie, Z. Q., Sonne, C., et al. (2022). Special Issue On The Amap 2021 Assessment Of Mercury In The Arctic. Science Of The Total Environment, 8438.
Abstract: This Editorial presents an overview of the Special Issue on advances in Arctic mercury (Hg) science synthesized from the 2021 assessment of the Arctic Monitoring and Assessment Programme (AMAP). Mercury continues to travel to Arctic environments and threaten wildlife and human health in this circumpolar region. Over the last decade, progress has been achieved in addressing policy-relevant uncertainties in environmental Hg contamination. This includes temporal trends of Hg, its transport to and within the Arctic, methylmercury cycling, climate change influences, biological effects of Hg on fish and wildlife, human exposure to Hg, and forecasting of Arctic responses to different future scenarios of anthropogenic Hg emissions. In addition, important contributions of Indigenous Peoples to Arctic research and monitoring of Hg are highlighted, including through projects of knowledge co-production. Finally, policy-relevant recommendations are summarized for future study of Arctic mercury. This series of scientific articles presents comprehensive information relevant to supporting effectiveness evaluation of the United Nations Minamata Convention on Mercury.
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Dofal, A., Michon, L., Fontaine, F., Rindraharisaona, E., Barruol, G., & Tkalcic, H. (2022). Imaging The Lithospheric Structure And Plumbing System Below Themayotte Volcanic Zone. Comptes Rendus Geoscience, 3543, 47–64.
Abstract: Teleseismic Receiver-Functions And Rayleigh-Wave Dispersion Curves Are Jointly Inverted For Quantifying S-Wave Velocity Profiles Beneath The Active Volcanic Zone Off Mayotte. We Show That The Lithosphere In The East-Northeast Quadrant Is Composed Of Fourmain Layers, Interpreted As The Volcanic Edifice, The Crust With Underplating, The Lithospheric Mantle, And The Asthenosphere, The Latter Two Presenting A Main Low-Velocity Zone. The Depths Of The Old (10-11 Km) And New Moho (28-31 Km) Coincide With The Two Magma Reservoirs Evidenced By Recent Seismological And Petrological Methods. We Propose That The Main Magma Reservoir Composed Of Mush With An Increasing Amount Of Liquid Extends Down To 54 Km Depth. This Magma Storage Develops From A Rheological Contrast Between The Ductile Lower And Brittle Upper Lithospheric Mantle And Accounts For Most Of The Volcanic Eruptionrelated Seismicity. Finally, The Abnormally Small Thickness Of The Lithosphericmantle (33 Km) Is Likely A Result Of A Thermal Thinning Since The Onset Of Cenozoic Magmatism.
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Domine, F., Fourteau, K., Picard, G., Lackner, G., Sarrazin, D., & Poirier, M. (2022). Permafrost Cooled In Winter By Thermal Bridging Through Snow-Covered shrub branches. Nature Geoscience, 151(7), 554–+.
Abstract: Considerable expansion of shrubs across the Arctic tundra has been observed in recent decades. These shrubs are thought to have a warming effect on permafrost by increasing snowpack thermal insulation, thereby limiting winter cooling and accelerating thaw. Here, we use ground temperature observations and heat transfer simulations to show that low shrubs can actually cool the ground in winter by providing a thermal bridge through the snowpack. Observations from unmanipulated herb tundra and shrub tundra sites on Bylot Island in the Canadian high Arctic reveal a 1.21 degrees C cooling effect between November and February. This is despite a snowpack that is twice as insulating in shrubs. The thermal bridging effect is reversed in spring when shrub branches absorb solar radiation and transfer heat to the ground. The overall thermal effect is likely to depend on snow and shrub characteristics and terrain aspect. The inclusion of these thermal bridging processes into climate models may have an important impact on projected greenhouse gas emissions by permafrost. Arctic shrubs cool permafrost in winter by acting as a thermal bridge through the snowpack, according to ground temperature observations and heat transfer simulations.
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Dominutti, P., Chevassus, E., Baray, J., Jaffrezo, J., Borbon, A., Colomb, A., et al. (2022). Evaluation Of The Sources, Precursors, And Processing Of Aerosols At A High-Altitude Tropical Site. Acs Earth And Space Chemistry, .
Abstract: This Work Presents The Results From A Set Of Aerosol- And Gas-Phase Measurements Collected During The Bio-Maido Field Campaign In Reunion Between March 8And April 5, 2019. Several Offline And Online Sampling Devices Were Installed At The Maido Observatory (Mo), A Remote High-Altitude Site In The Southern Hemisphere, Allowing The Physical And Chemical Characterization Of Atmospheric Aerosols And Gases. The Evaluation Of Short-Lived Gas-Phase Measurements Allows Us To Conclude That Air Masses Sampled During This Period Contained Little Or No Anthropogenic Influence. The Dominance Of Sulfate And Organic Species In The Submicron Fraction Of The Aerosol Is Similar To That Measured At Other Coastal Sites. Carboxylic Acids On Pm10 Showed A Significant Contribution Of Oxalic Acid, A Typical Tracer Of Aqueous Processed Air Masses, Increasing At The End Of The Campaign. This Result Agrees With The Positive Matrix Factorization Analysis Of The Submicron Organic Aerosol, Where More Oxidized Organic Aerosols (Mooas) Dominated The Organic Aerosol With An Increasing Contribution Toward The End Of The Campaign. Using A Combination Of Air Mass Trajectories (Model Predictions), It Was Possible To Assess The Impact Of Aqueous Phase Processing On The Formation Of Secondary Organic Aerosols (Soas). Our Results Show How Specific Chemical Signatures And Physical Properties Of Air Masses, Possibly Affected By Cloud Processing, Can Be Identified At Reunion. These Changes In Properties Are Represented By A Shift In Aerosol Size Distribution To Large Diameters And An Increased Contribution Of Secondary Sulfate And Organic Aerosols After Cloud Processing.
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Dominutti, P. A., Renard, P., Vaitilingom, M., Bianco, A., Baray, J. L., Borbon, A., et al. (2022). Insights into tropical cloud chemistry in Reunion (Indian Ocean): results from the BIO-MAiDO campaign. Atmospheric Chemistry And Physics, 222(1), 505–533.
Abstract: We present here the results obtained during an intensive field campaign conducted in the framework of the French “BIO-MAiDO” (Bio-physico-chemistry of tropical clouds at Maido (Reunion Island): processes and impacts on secondary organic aerosols' formation) project. This study integrates an exhaustive chemical and microphysical characterization of cloud water obtained in March-April 2019 in Reunion (Indian Ocean). Fourteen cloud samples have been collected along the slope of this mountainous island. Comprehensive chemical characterization of these samples is performed, including inorganic ions, metals, oxidants, and organic matter (organic acids, sugars, amino acids, carbonyls, and low-solubility volatile organic compounds, VOCs). Cloud water presents high molecular complexity with elevated water-soluble organic matter content partly modulated by microphysical cloud properties. As expected, our findings show the presence of compounds of marine origin in cloud water samples (e.g. chloride, sodium) demonstrating ocean-cloud exchanges. Indeed, Na+ and Cl- dominate the inorganic composition contributing to 30 % and 27 %, respectively, to the average total ion content. The strong correlations between these species (r(2) = 0.87, p value: < 0.0001) suggest similar air mass origins. However, the average molar Cl-/Na+ ratio (0.85) is lower than the sea-salt one, reflecting a chloride depletion possibly associated with strong acids such as HNO3 and H2SO4. Additionally, the non-sea-salt fraction of sulfate varies between 38 % and 91 %, indicating the presence of other sources. Also, the presence of amino acids and for the first time in cloud waters of sugars clearly indicates that biological activities contribute to the cloud water chemical composition. A significant variability between events is observed in the dissolved organic content (25.5 +/- 18.4 mgCL-1), with levels reaching up to 62 mgCL(-1). This variability was not similar for all the measured compounds, suggesting the presence of dissimilar emission sources or production mechanisms. For that, a statistical analysis is performed based on back-trajectory calculations using the CAT (Computing Atmospheric Trajectory Tool) model associated with the land cover registry. These investigations reveal that air mass origins and microphysical variables do not fully explain the variability observed in cloud chemical composition, highlighting the complexity of emission sources, multiphasic transfer, and chemical processing in clouds. Even though a minor contribution of VOCs (oxygenated and low-solubility VOCs) to the total dissolved organic carbon (DOC) (0.62 % and 0.06 %, respectively) has been observed, significant levels of biogenic VOC (20 to 180 nmolL(-1)) were detected in the aqueous phase, indicating the cloud-terrestrial vegetation exchange. Cloud scavenging of VOCs is assessed by measurements obtained in both the gas and aqueous phases and deduced experimental gas-/aqueous-phase partitioning was compared with Henry's law equilibrium to evaluate potential supersaturation or unsaturation conditions. The evaluation reveals the supersaturation of low-solubility VOCs from both natural and anthropogenic sources. Our results depict even higher supersaturation of terpenoids, evidencing a deviation from thermodynamically expected partitioning in the aqueous-phase chemistry in this highly impacted tropical area.
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Dommo, A., Vondou, D., Philippon, N., Eastman, R., Moron, V., & Aloysius, N. (2022). The Era5'S Diurnal Cycle Of Low-Level Clouds Over Western Central Africa During June-September: Dynamic And Thermodynamic Processes. Atmospheric Research, 2802.
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Dorschel, B., Hehemann, L., Viquerat, S., Warnke, F., Dreutter, S., Tenberge, Y. S., et al. (2022). The International Bathymetric Chart Of The Southern Ocean Version 2. Scientific Data, 9(1).
Abstract: The Southern Ocean surrounding Antarctica is a region that is key to a range of climatic and oceanographic processes with worldwide effects, and is characterised by high biological productivity and biodiversity. Since 2013, the International Bathymetric Chart of the Southern Ocean (IBCSO) has represented the most comprehensive compilation of bathymetry for the Southern Ocean south of 60 degrees S. Recently, the IBCSO Project has combined its efforts with the Nippon Foundation – GEBCO Seabed 2030 Project supporting the goal of mapping the world's oceans by 2030. New datasets initiated a second version of IBCSO (IBCSO v2). This version extends to 50 degrees S (covering approximately 2.4 times the area of seafloor of the previous version) including the gateways of the Antarctic Circumpolar Current and the Antarctic circumpolar frontal systems. Due to increased (multibeam) data coverage, IBCSO v2 significantly improves the overall representation of the Southern Ocean seafloor and resolves many submarine landforms in more detail. This makes IBCSO v2 the most authoritative seafloor map of the area south of 50 degrees S.
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dos Santos, T. C., Dominutti, P., Pedrosa, G. S., Coelho, M. S., Nogueira, T., Borbon, A., et al. (2022). Isoprene in urban Atlantic forests: Variability, origin, and implications on the air quality of a subtropical megacity. Science Of The Total Environment, 8248.
Abstract: Biosphere-atmosphere interactions play a key role in urban chemistry because of biogenic volatile organic compound (BVOC) emissions. Of the BVOC, isoprene is the most emitted compound; however, it also has anthropogenic origins in urban areas. In this study, we aimed to investigate the spatio-temporal variability and atmospheric impacts of biogenic and anthropogenic isoprene in the subtropical megacity of Sao Paulo (MASP), Brazil. Several measurement campaigns were conducted in three different urban Atlantic forests (Matao, PEFI, and RMG), and an urban background site (IAG); this equated to a total of 268 samples for the 2018-2019 period. For all sampling points, daytime average concentrations of isoprene were two to three times higher during the rainy season (IAG: 1.75 +/- 0.93 ppb; Matao: 0.87 +/- 0.35 ppb; PEFI: 0.50 +/- 0.30 ppb; RMG: 0.37 +/- 0.18 ppb), than those observed during the dry season (IAG: 0.46 +/- 0.24 ppb; Matao: 0.31 +/- 0.17 ppb; PEFI: 0.17 +/- 0.11 ppb; RMG: 0.11 +/- 0.07 ppb). Average isoprene concentrations were similar to those observed in other places worldwide, with the exception of theAmazon forest. Our results indicate differences in isoprene concentrations between sites, suggesting that environmental conditions such as the urban heat island and vegetation types, may play a role in spatial variability. Estimates of the isoprene fraction indicated that the biogenic fraction (85%) surpassed the anthropogenic fraction during the rainy season. By contrast, the anthropogenic fraction (52%) exceeded the biogenic fraction during dry periods. These fractions have an impact on potentially forming secondary pollutants gaseous (ozone formation potential: 7.19-33.32 μg m(-3)), and aerosols (secondary organic aerosols formation potential: 0.41-1.88 μg m(-3)). These results highlight the role of biogenic isoprene and its potential impact on urban air quality in subtropicalmegacities; this requires further investigation under future climate change scenarios.
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Doscher, R., Acosta, M., Alessandri, A., Anthoni, P., Arsouze, T., Bergman, T., et al. (2022). The Ec-Earth3 Earth System Model For The Coupled Model Intercomparison Project 6. Geoscientific Model Development, 151(7), 2973–3020.
Abstract: The Earth system model EC-Earth3 for contributions to CMIP6 is documented here, with its flexible coupling framework, major model configurations, a methodology for ensuring the simulations are comparable across different high-performance computing (HPC) systems, and with the physical performance of base configurations over the historical period. The variety of possible configurations and sub-models reflects the broad interests in the EC-Earth community. EC-Earth3 key performance metrics demonstrate physical behavior and biases well within the frame known from recent CMIP models. With improved physical and dynamic features, new Earth system model (ESM) components, community tools, and largely improved physical performance compared to the CMIP5 version, EC-Earth3 represents a clear step forward for the only European community ESM. We demonstrate here that EC-Earth3 is suited for a range of tasks in CMIP6 and beyond.
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Durand, G., van den Broeke, M. R., Le Cozannet, G., Edwards, T. L., Holland, P. R., Jourdain, N. C., et al. (2022). Sea-Level Rise: From Global Perspectives to Local Services. Frontiers In Marine Science, 8.
Abstract: Coastal areas are highly diverse, ecologically rich, regions of key socio-economic activity, and are particularly sensitive to sea-level change. Over most of the 20th century, global mean sea level has risen mainly due to warming and subsequent expansion of the upper ocean layers as well as the melting of glaciers and ice caps. Over the last three decades, increased mass loss of the Greenland and Antarctic ice sheets has also started to contribute significantly to contemporary sea-level rise. The future mass loss of the two ice sheets, which combined represent a sea-level rise potential of similar to 65 m, constitutes the main source of uncertainty in long-term (centennial to millennial) sea-level rise projections. Improved knowledge of the magnitude and rate of future sea-level change is therefore of utmost importance. Moreover, sea level does not change uniformly across the globe and can differ greatly at both regional and local scales. The most appropriate and feasible sea level mitigation and adaptation measures in coastal regions strongly depend on local land use and associated risk aversion. Here, we advocate that addressing the problem of future sea-level rise and its impacts requires (i) bringing together a transdisciplinary scientific community, from climate and cryospheric scientists to coastal impact specialists, and (ii) interacting closely and iteratively with users and local stakeholders to co-design and co-build coastal climate services, including addressing the high-end risks.
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Ershadi, M. R., Drews, R., Martin, C., Eisen, O., Ritz, C., Corr, H., et al. (2022). Polarimetric Radar Reveals The Spatial Distribution Of Ice Fabric At domes and divides in East Antarctica. Cryosphere, 161(5), 1719–1739.
Abstract: Ice crystals are mechanically and dielectrically anisotropic. They progressively align under cumulative deformation, forming an ice-crystal-orientation fabric that, in turn, impacts ice deformation. However, almost all the observations of ice fabric are from ice core analysis, and its influence on the ice flow is unclear. Here, we present a non-linear inverse approach to process co- and cross-polarized phase-sensitive radar data. We estimate the continuous depth profile of georeferenced ice fabric orientation along with the reflection ratio and horizontal anisotropy of the ice column. Our method approximates the complete second-order orientation tensor and all the ice fabric eigenvalues. As a result, we infer the vertical ice fabric anisotropy, which is an essential factor to better understand ice deformation using anisotropic ice flow models. The approach is validated at two Antarctic ice core sites (EPICA (European Project for Ice Coring in Antarctica) Dome C and EPICA Dronning Maud Land) in contrasting flow regimes. Spatial variability in ice fabric characteristics in the dome-to-flank transition near Dome C is quantified with 20 more sites located along with a 36 km long cross-section. Local horizontal anisotropy increases under the dome summit and decreases away from the dome summit We suggest that this is a consequence of the nonlinear rheology of ice, also known as the Raymond effect. On larger spatial scales, horizontal anisotropy increases with increasing distance from the dome. At most of the sites, the main driver of ice fabric evolution is vertical compression, yet our data show that the horizontal distribution of the ice fabric is consistent with the present horizontal flow. This method uses polarimetric-radar data, which are suitable for profiling radar applications and are able to constrain ice fabric distribution on a spatial scale comparable to ice flow observations and models.
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Espinoza, J. C., Marengo, J. A., Schongart, J., & Jimenez, J. C. (2022). The New Historical Flood Of 2021 In The Amazon River Compared To Major floods of the 21st century: Atmospheric features in the context of the intensification of floods. Weather And Climate Extremes, 353.
Abstract: In June 2021 a new extreme flood was reported in the Amazon Basin, the largest hydrological system on Earth. During this event water level was above 29 m (the emergency threshold) for 91 days at Manaus station (Brazil), surpassing even the previous historical flood of 2012. Since the late 1990s, 9 extreme floods occurred, while only 8 events were reported from 1903 to 1998. Here we report that the 2021 flood is associated with an intensification of the atmospheric upward motion in the northern Amazonia (5?degrees S-5?degrees N), which is related to an intensification of the Walker circulations. This atmospheric feature is associated with an enhanced of deep convective clouds and intense rainfall over the northern Amazonia that produce positive anomalies of terrestrial water storage over northern Amazonia in the 2021 austral summer. The intensification of Walker circulation is associated with La Nina conditions that characterize the major floods observed in Amazonia during the 21st century (2009, 2012 and 2021). However, during the 2021 an intensification of the continental Hadley circulation is also observed. This feature produces simultaneous dry conditions over southern and southeastern Amazonia, where negative rainfall anomalies, low frequency of deep convective clouds and negative anomalies of terrestrial water storage are observed.
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Fain, X., Rhodes, R. H., Place, P., Petrenko, V. V., Fourteau, K., Chellman, N., et al. (2022). Northern Hemisphere atmospheric history of carbon monoxide since preindustrial times reconstructed from multiple Greenland ice cores. Climate Of The Past, 181(3), 631–647.
Abstract: Carbon monoxide (CO) is a regulated pollutant and one of the key components determining the oxidizing capacity of the atmosphere. Obtaining a reliable record of atmospheric CO mixing ratios ([CO]) since preindustrial times is necessary to evaluate climate-chemistry models under conditions different from today and to constrain past CO sources. We present high-resolution measurements of CO mixing ratios from ice cores drilled at five different sites on the Greenland ice sheet that experience a range of snow accumulation rates, mean surface temperatures, and different chemical compositions. An optical-feedback cavity-enhanced absorption spectrometer (OF-CEAS) was coupled with continuous melter systems and operated during four analytical campaigns conducted between 2013 and 2019. Overall, continuous flow analysis (CFA) of CO was carried out on over 700 m of ice. The CFA-based CO measurements exhibit excellent external precision (ranging from 3.3 to 6.6 ppbv, 1 sigma) and achieve consistently low blanks (ranging from 4.1 +/- 1.2 to 12.6 +/- 4.4 ppbv), enabling paleoatmospheric interpretations. However, the five CO records all exhibit variability that is too large and rapid to reflect past atmospheric mixing ratio changes. Complementary tests conducted on discrete ice samples demonstrate that these variations are not artifacts of the analytical method (i.e., production of CO from organics in the ice during melting) but are very likely related to in situ CO production within the ice before analysis. Evaluation of the signal resolution and co-investigation of high-resolution records of CO and total organic carbon (TOC) suggest that past atmospheric CO variations can be extracted from the records' baselines with accumulation rates higher than 20 cm w.e. yr(-1) (water equivalent per year). Consistent baseline CO records from four Greenland sites are combined to produce a multisite average ice core reconstruction of past atmospheric CO for the Northern Hemisphere high latitudes, covering the period from 1700 to 1957 CE. Such a reconstruction should be taken as an upper bound of past atmospheric CO abundance. From 1700 to 1875 CE, the record reveals stable or slightly increasing values in the 100-115 ppbv range. From 1875 to 1957 CE, the record indicates a monotonic increase from 114 +/- 4 to 147 +/- 6 ppbv. The ice core multisite CO record exhibits an excellent overlap with the atmospheric CO record from Green-land firn air which spans the 1950-2010 CE time period. The combined ice core and firn air CO history, spanning 1700-2010 CE, provides useful constraints for future model studies of atmospheric changes since the preindustrial period.
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Fan, L., Al-Yaari, A., Frappart, F., Peng, J., Wen, J. G., Xiao, Q., et al. (2022). Estimating High-Resolution Soil Moisture Over Mountainous Regions Using Remotely-Sensed Multispectral and Topographic Data. Ieee Journal Of Selected Topics In Applied Earth Observations And Remote SENSING, 151, 3637–3649.
Abstract: A surface soil moisture (SM) condition at high spatiotemportal resolutions is required by regional Earth system applications. Here, we mapped daily 1-km SM in the Babao River Basin in the northwest of China during the summers from 2013 to 2015 using a random forest (RF) method by merging SM information retrieved from in situ measurements, optical/thermal remote sensing, and topographical indices. Relative importance analysis was used to determine the optimal predictors for estimating high-resolution SM. A specific RF model (RFVI+sup) was constructed using the optimal predictors including remote sensing albedo, apparent thermal inertia (ATI), normalized difference vegetation index, normalized difference infrared index 5, soil adjusted vegetation index, and topographical indices (aspect and elevation). The RFVI+sup also accounted for missing observations of the thermal index (e.g., ATI) over the mountainous regions. In the comparison between the SM estimates using the new RFVI+sup model and other RF models, the spatial coverage of available estimates increased from 14% to 64% over the study region, the correlation coefficient values were improved to 0.75, the unbiased root-mean-squared difference values decreased to 0.032 m(3)/m(3). Thus, the proposed RF method provided accurate SM estimates with high spatiotemporal resolution over the mountainous regions, by merging multiresource datasets from in situ measurements, remotely-sensed, and topographical indices.
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Fang, G., Li, Z., Yang, J., Chen, Y., Duan, W., Amory, C., et al. (2022). Changes In Flooding In The Alpine Catchments Of The Tarim River Basin, Central Asia. Journal Of Flood Risk Management, .
Abstract: Floods Are One Of The Most Affective Climate-Related Disasters, And Climate Change Has Altered Their Intensity And Frequency Worldwide. This Study Examined Long-Term Changes In Flood Characteristics (Including Magnitude, Frequency, And Timing) In 30 Alpine Headwaters Of The Large Endorheic Tarim River Basin, Central Asia. The Contributions Of Climatic Factors To Flood (Magnitude And Timing) Changes Were Investigated Using Numerical Experiments In Combination With The Random Forest Approach. The Following Results Were Obtained: (1) Annual Maximum Flood Peaks Increased At Most Stations (89% Stations) During 1961-2015 With Increased Flood Frequency. Earlier Flood Peaks Were Observed In Spring With A Rate Of 1.38 Day Per Decade; For Other Seasons, Changes In The Occurrence Time Of Flood Peaks Showed Strong Spatial Variability. (2) Precipitation Was The Dominant Factor For The Increased Flood Magnitude In Most Catchments Of The Southern Slope Of The Tianshan Mountains, And Temperature Played A Greater Role In The Northern Kunlun Mountains. (3) For Flood Timing Changes, Melt Level Height And Precipitation Were The Most Influential Factors In The Alpine Catchments In The Tarim River Basin. The Results Provide Information On The Spatiotemporal Variations Of Floods And Their Driving Factors In This Alpine Basin Under Climate Change.
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Fang, G., Yang, J., Li, Z., Chen, Y., Duan, W., Amory, C., et al. (2022). Shifting In The Global Flood Timing. Scientific Reports, 121(1).
Abstract: Climate Change Will Have An Impact On Not Only Flood Magnitude But Also On Flood Timing. This Paper Studies The Shifting In Flood Timing At 6167 Gauging Stations From 1970 To 2010, Globally. The Shift In Flood Timing And Its Relationship With Three Influential Factors (Maximum 7-Day Precipitation, Soil Moisture Excess, And Snowmelt) Are Investigated. There Is A Clear Global Pattern In The Mean Flooding Date: Winter (Dec-Feb) Across The Western Coastal America, Western Europe And The Mediterranean Region, Summer (Jun-Aug) In The North America, The Alps, Indian Peninsula, Central Asia, Japan, And Austral Summer (Dec-Feb) In South Africa And North Australia Area. The Shift In Flood Timing Has A Trend From – 22 Days Per Decade (Earlier) To 28 Days Per Decade (Delayed). Earlier Floods Were Found Extensively In The North America, Europe And Northeast Australia While Delayed Floods Were Prevailing In The Amazon, Cerrado, South Africa, India And Japan. Earlier Flood Timing In The North America And Europe Was Caused By Earlier Snowmelt While Delayed Extreme Soil Moisture Excess And Precipitation Have Jointly Led To Delayed Floods Around The Monsoon Zone, Including South Africa, India And Japan. This Study Provides An Insight On The Shifting Mechanism Of Flood Timing, And Supports Decisions On The Global Flood Mitigation And The Impact From Future Climate Change.
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Fleurbaey, H., Campargue, A., Da Silva, Y. C. M., Grilli, R., Kassi, S., & Mondelain, D. (2022). Characterization Of The H2O + Co2 Continuum Within The Infrared transparency windows. Journal Of Quantitative Spectroscopy & Radiative Transfer, 2822.
Abstract: Absorption spectra of humidified CO2 have been recorded at room temperature by cavity enhanced absorption techniques (CRDS and OFCEAS): (i) in three spectral ranges of the 1.6 μm window (5720-6045 cm (-1); 6390-6460 cm (-1) and 6570-6665 cm -1), (ii) in four narrow spectral intervals of the 2.3 μm window (4243-4255 cm(-1); 4301.3-4302 cm(-1); 4 421.5-4 4 40 cm(-1)and 4518-4535 cm( -1)), and (iii) around 2853 cm( -1). All these spectral ranges are situated in transparency windows of both H2O and CO2. The binary absorption coefficients (BC O-2-H2O +BH2O-C O-2) are retrieved from low pressure spectra ( < 1 atm) recorded with different molar fractions of water vapor in CO2 after subtracting the H2O and CO2 local monomer contributions and the self-continuum contribution of each species (i.e. H2O -H2O and CO2-CO2). Experimental room temperature binary coefficients are then compared to the only available empirical model based on line shape profiles with chi-factors. This model well reproduces our experimental values on the low-and high-frequency edges of the 1.6 μm window and gives a relatively good agreement for the 2853 cm( -1) data point. Larger differences are observed in the 2.3 μm window where the calculated values are underestimated by a factor of 3. Around 60 0 0 cm( -1), an additional absorption peak is observed which is tentatively interpreted as a collision induced absorption band due to the simultaneous excitation of the H2O and CO2 molecules. (C)& nbsp;2022 Elsevier Ltd. All rights reserved.
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Fleurbaey, H., Campargue, A., Da Silva, Y. C. M., Grilli, R., Kassi, S., & Mondelain, D. (2022). Characterization Of The H2O + Co2 Continuum Within The Infrared transparency windows. Journal Of Quantitative Spectroscopy & Radiative Transfer, 2822.
Abstract: Absorption spectra of humidified CO2 have been recorded at room temperature by cavity enhanced absorption techniques (CRDS and OFCEAS): (i) in three spectral ranges of the 1.6 μm window (5720-6045 cm (-1); 6390-6460 cm (-1) and 6570-6665 cm -1), (ii) in four narrow spectral intervals of the 2.3 μm window (4243-4255 cm(-1); 4301.3-4302 cm(-1); 4 421.5-4 4 40 cm(-1)and 4518-4535 cm( -1)), and (iii) around 2853 cm( -1). All these spectral ranges are situated in transparency windows of both H2O and CO2. The binary absorption coefficients (BC O-2-H2O +BH2O-C O-2) are retrieved from low pressure spectra ( < 1 atm) recorded with different molar fractions of water vapor in CO2 after subtracting the H2O and CO2 local monomer contributions and the self-continuum contribution of each species (i.e. H2O -H2O and CO2-CO2). Experimental room temperature binary coefficients are then compared to the only available empirical model based on line shape profiles with chi-factors. This model well reproduces our experimental values on the low-and high-frequency edges of the 1.6 μm window and gives a relatively good agreement for the 2853 cm( -1) data point. Larger differences are observed in the 2.3 μm window where the calculated values are underestimated by a factor of 3. Around 60 0 0 cm( -1), an additional absorption peak is observed which is tentatively interpreted as a collision induced absorption band due to the simultaneous excitation of the H2O and CO2 molecules. (C)& nbsp;2022 Elsevier Ltd. All rights reserved.
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Fleurbaey, H., Grilli, R., Mondelain, D., & Campargue, A. (2022). Measurements of the water vapor continuum absorption by OFCEAS at 3.50 μm and 2.32 μm. Journal Of Quantitative Spectroscopy & Radiative Transfer, 2782.
Abstract: Measurements of the water vapor absorption cross-sections at two spectral points of the 2.1 μm and 4.0 μm transparency windows are performed by optical feedback cavity enhanced absorption spectroscopy (OFCEAS). The self-continuum cross-section, C-s, is measured for temperature values of 30 and 47 degrees C (303 and 320 K) at the 2853 cm(-1) spectral point, corresponding to the lowest opacity region of the 4.0 μm transparency window. The C-s values derived from the pressure squared dependence of the self-continuum, are found consistent with previous CEAS measurements in the considered window but significantly smaller than measurements by Fourier transform spectroscopy (FTS). The C-s temperature dependence is discussed in relation with FTS measurements at high temperature. Foreign-continuum cross-sections, C-F, are newly obtained from OFCEAS spectra of moist air in flow regime at the 4302 cm(-1) spectral point of the low energy edge of the 2.1 μm window. After subtraction of the monomer and self-continuum contributions, C-F values are derived from the linear variation of the foreign-continuum absorption with the product of the water vapor and air partial pressures. The measurements were performed for temperature values of 34 and 47 degrees C (307 and 320 K) and no significant temperature dependency was observed. The present C-F value at 4302 cm(-1) is gathered with previous CEAS measurements at seven spectral points of the 2.1 μm window. This consistent set of C-F values is used to derive from a polynomial fit, the empirical frequency dependence of C-F(v) over the 4250-5000 cm(-1) range. Overall, the semi-empirical MTCKD3.5 values of C-F are significantly underestimated in the centre of the considered window. (C) 2021 Elsevier Ltd. All rights reserved.
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Foret, G., Michoud, V., Kotthaus, S., Petit, J., Baudic, A., Siour, G., et al. (2022). The December 2016 Extreme Weather And Particulate Matter Pollution Episode In The Paris Region (France). Atmospheric Environment, 2912.
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Fotso-Nguemo, T., Vondou, D., Diallo, I., Diedhiou, A., Weber, T., Tanessong, R., et al. (2022). Potential impact of 1.5, 2 and 3 degrees C global warming levels on heat and discomfort indices changes over Central Africa. Science Of The Total Environment, 804.
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Francis, D., Fonseca, R., Nelli, N., Bozkurt, D., Picard, G., & Guan, B. (2022). Atmospheric rivers drive exceptional Saharan dust transport towards Europe. Atmospheric Research, 2662.
Abstract: This study highlights the occurrence of atmospheric rivers (ARs) over northwest Africa towards Europe, which were accompanied by intense episodes of Saharan dust transport all the way to Scandinavia, in the winter season. Using a combination of observational and reanalysis data, we investigate two extreme dusty AR events in February 2021 and assess their impact on snow melt in the Alps. The warm, moist, and dusty air mass (spatially-averaged 2-meter temperature and water vapour mixing ratio anomalies of up to 8 K and 3 g kg(-1), and aerosol optical depths and dust loadings of up to 0.85 and 11 g m (2), respectively) led to a 50% and 40% decrease in snow depth and surface albedo, respectively, in less than one month during the winter season. ARs over northwest Africa show increasing trends over the past 4 decades, with 78% of AR events associated with severe dust episodes over Europe.
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Frezat, H., Le Sommer, J., Fablet, R., Balarac, G., & Lguensat, R. (2022). A Posteriori Learning For Quasi-Geostrophic Turbulence Parametrization. Journal Of Advances In Modeling Earth Systems, 141(111).
Abstract: The Use Of Machine Learning To Build Subgrid Parametrizations For Climate Models Is Receiving Growing Attention. State-Of-The-Art Strategies Address The Problem As A Supervised Learning Task And Optimize Algorithms That Predict Subgrid Fluxes Based On Information From Coarse Resolution Models. In Practice, Training Data Are Generated From Higher Resolution Numerical Simulations Transformed In Order To Mimic Coarse Resolution Simulations. By Essence, These Strategies Optimize Subgrid Parametrizations To Meet So-Called A Priori Criteria. But The Actual Purpose Of A Subgrid Parametrization Is To Obtain Good Performance In Terms Of A Posteriori Metrics Which Imply Computing Entire Model Trajectories. In This Paper, We Focus On The Representation Of Energy Backscatter In Two-Dimensional Quasi-Geostrophic Turbulence And Compare Parametrizations Obtained With Different Learning Strategies At Fixed Computational Complexity. We Show That Strategies Based On A Priori Criteria Yield Parametrizations That Tend To Be Unstable In Direct Simulations And Describe How Subgrid Parametrizations Can Alternatively Be Trained End-To-End In Order To Meet A Posteriori Criteria. We Illustrate That End-To-End Learning Strategies Yield Parametrizations That Outperform Known Empirical And Data-Driven Schemes In Terms Of Performance, Stability, And Ability To Apply To Different Flow Configurations. These Results Support The Relevance Of Differentiable Programming Paradigms For Climate Models In The Future.
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Fugger, S., Fyffe, C. L., Fatichi, S., Miles, E., McCarthy, M., Shaw, T. E., et al. (2022). Understanding Monsoon Controls On The Energy And Mass Balance Of glaciers in the Central and Eastern Himalaya. Cryosphere, 161(5), 1631–1652.
Abstract: The Indian and East Asian summer monsoons shape the melt and accumulation patterns of glaciers in High Mountain Asia in complex ways due to the interaction of persistent cloud cover, large temperature ranges, high atmospheric water content and high precipitation rates. Glacier energy- and mass-balance modelling using in situ measurements offers insights into the ways in which surface processes are shaped by climatic regimes. In this study, we use a full energy- and mass-balance model and seven on-glacier automatic weather station datasets from different parts of the Central and Eastern Himalaya to investigate how monsoon conditions influence the glacier surface energy and mass balance. In particular, we look at how debris-covered and debris-free glaciers respond differently to monsoonal conditions. The radiation budget primarily controls the melt of cleanice glaciers, but turbulent fluxes play an important role in modulating the melt energy on debris-covered glaciers. The sensible heat flux decreases during core monsoon, but the latent heat flux cools the surface due to evaporation of liquid water. This interplay of radiative and turbulent fluxes causes debris-covered glacier melt rates to stay almost constant through the different phases of the monsoon. Ice melt under thin debris, on the other hand, is amplified by both the dark surface and the turbulent fluxes, which intensify melt during monsoon through surface heating and condensation. Pre-monsoon snow cover can considerably delay melt onset and have a strong impact on the seasonal mass balance. Intermittent monsoon snow cover lowers the melt rates at high elevation. This work is fundamental to the understanding of the present and future Himalayan cryosphere and water budget, while informing and motivating further glacier- and catchment-scale research using process-based models.
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Gaubert-Bastide, T., Garambois, S., Bordes, C., Voisin, C., Oxarango, L., Brito, D., et al. (2022). High-Resolution Monitoring Of Controlled Water Table Variations From Dense Seismic-Noise Acquisitions. Water Resources Research, 585(8).
Abstract: Water-Resource Management Has Become A Major Global Issue In A World Threatened By Climate Change. High-Resolution Geophysical Methods May Be Of Valuable Help In Monitoring The Water Masses, Both In Space And Time. Passive Seismic Interferometry Takes Advantage Of Ambient Seismic Noise To Recover The Variations In Seismic Wave Velocity Induced By Changes In Groundwater. We Present Hereafter The Time And Space Monitoring Of An Hydraulic Dome Artificially Formed To Prevent Biological And Chemical Pollutants From Entering The Exploitation Field Of Crepieux-Charmy (Lyon, France). We Use A Dense Seismic Network To Passively Monitor The Water Table Changes Induced By Infilling Of An Infiltration Basin At The Water Supply Facility For The Two Million Inhabitants Of The Lyon Metropolis (France). We Assess The Hourly Seismic Velocity Variations Over 19 Days, During Which Two Filling And Drainage Cycles Were Performed. The Use Of A Dense Three-Component Seismic Network Allows Fine Characterization Of The Seismic Wavefield, And Offers The Possibility To Include The Analysis Of 4,851 Raypaths In A Robust Inversion Algorithm Based On Ray Theory. The Velocity Variations Are Mapped With High Resolution. They Are Directly Related To The Water Table Variations And To Residual Water Saturation Changes Within The Unsaturated Zone. This Seismic Experiment Highlights The Three-Dimensional (3D) Implementation And Evolution Of A Hydraulic Dome Under The Infiltration Basin. This Dynamic Information Helps In The Understanding And Modeling Of Water Flows Between The Water Table And A River, Which Represents A Fundamental Issue For Discussions On The Effectiveness Of The Barrier.
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Gaubert-Bastide, T., Garambois, S., Bordes, C., Voisin, C., Oxarango, L., Brito, D., et al. (2022). High-Resolution Monitoring Of Controlled Water Table Variations From Dense Seismic-Noise Acquisitions. Water Resources Research, 585(8).
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Geindreau, C., Emeriault, F., Dadda, A., Yaba, O., Spadini, L., Filet, A., et al. (2022). Mechanical and Microstructural Changes of Biocemented Sand Subjected to an Acid Solution. International Journal Of Geomechanics, 22(3).
Abstract: An experimental study was performed to investigate the effects of an acid solution on the mechanical strength and the microstructure of biocemented sand. The tests were performed on small triaxial samples extracted from a large-scale model. An acid solution composed of hydrochloric acid and Tris buffer with an initial pH of 6.6 was injected in the triaxial apparatus in different amounts. The changes of the physical and mechanical properties of the sample were studied afterwards. Triaxial drained tests with constant confining pressures were performed on the chemically treated samples in order to determine the remaining strength of the samples. Moreover, several scanning electron microscope (SEM) and X-ray microtomography observations were performed on small subsamples in order to identify the changes in the microstructure due to the chemical dissolution. The experimental results point out that the strength of the treated specimens decreases dramatically compared with that of the initial untreated specimens. Typically, a 50% strength reduction has been found for 10% of total calcite dissolution. Furthermore, the microstructural observations have shown uniform calcite dissolution at the pore scale (no preferential locations). The calcite crystal structures were damaged randomly by the chemical solution. A reduction of the spatial densities and sizes of these crystals were found from SEM and X-ray microtomography observations. Overall, no hysteretic effects were observed on the mechanical (strength) and microstructural (contact surface area) properties between the biocementation and dissolution paths.
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Genthon, C., Veron, D. E., Vignon, E., Madeleine, J. B., & Piard, L. (2022). Water vapor in cold and clean atmosphere: a 3-year data set in the boundary layer of Dome C, East Antarctic Plateau. Earth System Science Data, 141(4), 1571–1580.
Abstract: The air at the surface of the high Antarctic Plateau is very cold, dry and clean. Under such conditions, the atmospheric moisture can significantly deviate from thermodynamic equilibrium, and supersaturation with respect to ice can occur. Most conventional humidity sensors for meteorological applications cannot report supersaturation in this environment. A simple approach for measuring supersaturation using conventional instruments, with one being operated in a heated airflow, is presented. Since 2018, this instrumental setup has been deployed at three levels in the lower similar to 40m above the surface at Dome C on the high Antarctic Plateau. A resulting 3-year (2018-2020) record (Genthon et al., 2021a) is presented and analyzed for features such as the frequency of supersaturation with respect to ice, diurnal and seasonal variability, and vertical distribution. As supercooled liquid water droplets are frequently observed in clouds at the temperatures experienced on the high Antarctic Plateau, the distribution of relative humidity with respect to liquid water at Dome C is also discussed. It is suggested that, while not strictly mimicking the conditions of the high troposphere, the surface atmosphere on the Antarctic Plateau is a convenient natural laboratory to test parametrizations of cold microphysics predominantly developed to handle the genesis of high tropospheric clouds. Data are available from the PANGAEA data repository at https://doi.org/10.1594/PANGAEA.939425 (Genthon et al., 2021a).
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Gilbert, A., Gimbert, F., Thogersen, K., Schuler, T. V., & Kaab, A. (2022). A Consistent Framework For Coupling Basal Friction With Subglacial Hydrology on Hard-Bedded Glaciers. Geophysical Research Letters, 494(131).
Abstract: Below hard-bedded glaciers, both basal friction and distributed subglacial drainage are thought to be controlled by a network of cavities. Previous coupled hydro-mechanical models, however, describe cavity-driven friction and hydraulic transmissivity independently, resulting in a physically inconsistent cavity evolution between the two components of the models. Here, we overcome this issue by describing the hydro-mechanical system using a common cavity-evolution description, that governs both transient friction and hydraulic transmissivity. We show that our coupling approach is superior to previous formulations in explaining a unique observation record of glacier sliding speed from the French Alps. We find that, at multi-day to multi-decadal timescales, sliding speed can be expressed as a direct function of basal shear stress and water discharge, without accounting for water pressure, which simply adjusts to maintain the cavitation ratio needed to accommodate the water supply.
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Gonzalez-Garcia, A., Palomo, I., Arboledas, M., Gonzalez, J., Mugica, M., Mata, R., et al. (2022). Protected Areas As A Double Edge Sword: An Analysis Of Factors Driving Urbanisation In Their Surroundings. Global Environmental Change-Human And Policy Dimensions, 747.
Abstract: Protected Areas (Pas) Are The Most Effective Tools To Protect Biodiversity And Ecosystem Services. They Have Proven To Be Effective In Stopping Extensive Land Use Conversion In Well-Conserved Terrestrial Ecosystems. However, Land Cover Changes Around Pas Threaten Biodiversity And Ecosystem Services Within Their Limits And Reduce Ecological Connectivity. In This Study, We Analysed The Urban Sprawls On The Boundaries Of 159 Pas (National, Regional, And Natural Parks) In Spain, Using 2.5 And 5 Km Non-Protected Buffer Zones From 1990 To 2018. We Clustered Pas Based On Biophysical And Socio-Economic Characteristics And Modelled Urban Sprawl In Different Buffers And Periods. Hierarchical Clustering Revealed Three Groups Of Pas: (A) Proximate Urban Parks, (B) Mountainous Parks, And (C) Parks In The Madrid Autonomous Region. We Found That Urbanisation In The Surroundings Of Pas In Spain Has Nearly Doubled Since 1990. General Linear Models Explained A Significant Proportion Of The Urbanisation Trends Observed, With The Number Of Municipalities In The Boundary Of The Pa, The Distance To A Main Road, And The Distance To A Big City Acting As The Most Important Drivers Of Urban Sprawl. Our Results Also Show That Some Pas Exert Significant Effects On Urbanisation Trends In Their Surroundings Through The Park-View Effect. Finally, We Highlight Three Coexisting Phenomena That Might Explain The Observed Urban Sprawl Processes: (A) Pas Attracting Urbanisation In Their Surroundings Due To The Park-View Effect, (B) Pas As A Deterrent For Urban Sprawl Within Their Limits, And (C) Pas Occupying Residual Areas Among Previously Urbanised Lands.
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Grange, S. K., Uzu, G., Weber, S., Jaffrezo, J. L., & Hueglin, C. (2022). Linking Switzerland'S Pm10 And Pm2.5 Oxidative Potential (Op) With emission sources. Atmospheric Chemistry And Physics, 222(101), 7029–7050.
Abstract: Particulate matter (PM) is the air pollutant that causes the greatest deleterious health effects across the world, so PM is routinely monitored within air quality networks, usually in respect to PM mass or number in different size fractions. However, such measurements do not provide information on the biological toxicity of PM. Oxidative potential (OP) is a complementary metric that aims to classify PM in respect to its oxidising ability in the lungs and is being increasingly reported due to its assumed relevance concerning human health. Between June 2018 and May 2019, an intensive filter-based PM sampling campaign was conducted across Switzerland in five locations, which involved the quantification of a large number of PM constituents and the OP for both PM10 and PM2.5. OP was quantified by three assays: ascorbic acid (AA), dithiothreitol (DTT), and dichlorofluorescein (DCFH). OPv (OP by air volume) was found to be variable over time and space: Bern-Bollwerk, an urban-traffic sampling site, had the greatest levels of OPv among the Swiss sites (especially when considering OPvAA ), with more rural locations such as Payerne experiencing a lower OPv. However, urban-background and suburban sites experienced a significant OPv enhancement, as did the rural Magadino-Cadenazzo site during wintertime because of high levels of wood smoke. The mean OP ranges for the sampling period were 0.4-4.1 nmolmin(-1)m(-3), 0.6-3.0 nmolmin(-1)m(-3), and 0.3-0.7 nmolH(2)O(2)m(-3) for OPvAA, OPDvTT, and OPvDCFH, respectively. A source allocation method using positive matrix factorisation (PMF) models indicated that although all PM10 and PM2.5 sources that were identified contributed to OPv, the anthropogenic road traffic and wood combustion sources had the greatest OPm potency (OP per PM mass) on average. A dimensionality reduction procedure coupled to multiple linear regression modelling consistently identified a handful of metals usually associated with nonexhaust emissions, namely copper, zinc, iron, tin, antimony, manganese, and cadmium, as well as three specific wood-burning-sourced organic tracers – levoglucosan, mannosan, and galactosan (or their metal substitutes: rubidium and potassium), as the most important PM components to explain and predict OPv. The combination of a metal and a wood-burning-specific tracer led to the best-performing linear models to explain OPv. Interestingly, within the non-exhaust and wood combustion emission groups, the exact choice of component was not critical; the models simply required a variable representing the emission source or process to be present. This analysis strongly suggests that anthropogenic and locally emitting road traffic and wood burning sources should be prioritised, targeted, and controlled to gain the most efficacious decrease in OPv and presumably biological harm reductions in Switzerland.
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Grey, L., Johnson, A. V., Matthews, T., Perry, L. B., Elmore, A. C., Khadka, A., et al. (2022). Mount Everest's photogenic weather during the post-monsoon. Weather, .
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Grima, C., Mouginot, J., Kofman, W., Herique, A., & Beck, P. (2022). The Basal Detectability of an Ice-Covered Mars by MARSIS. Geophysical Research Letters, 494(2).
Abstract: The detection of anomalously strong relative basal reflectivity beneath the Martian South Polar Layered Deposits (SPLD) from the Mars Advanced Radar for Subsurface and Ionosphere Sounding (MARSIS) has led to hypotheses suggesting the presence of basal materials such as liquid water. Here, we propose a forward approach to assess whether such a high signal could be produced by a Martian terrain currently exposed at the surface without liquid water. We convert existing MARSIS surface reflectivity measurements into a basal reflectivity as if it were overlaid by an SPLD-like ice deposit. 0.3%-2% of the surface could produce basal reflections of magnitude similar to the SPLD measurements in the assumption of a 10% impure ice. An ice loss tangent > $ > $0.01 is required to prevent any of the current Martian surface from producing a bright SPLD-like basal reflection. The detected bright terrains are gathered within volcanic constructs of diverse geologic epoch.
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Hachgenei, N., Nord, G., Spadini, L., Mora, H., Courvoisier, F., Sutra, J. F., et al. (2022). A device to simulate contaminant transfer and surface and subsurface flow through intact soil monoliths. Vadose Zone Journal, .
Abstract: Many contaminants of agricultural origin are released into rural environments, particularly at the soil surface. Their fate has been extensively investigated in repacked soils, but only few studies have addressed their transport in structurally preserved natural soils. Much remains unknown about their fate and transfer within and between environmental compartments, while the susceptibility of these compartments to the contaminants adverse effects can vary considerably. The lack of studies regarding surface and subsurface transfer of contaminants through intact soil compared with studies on repacked soil led us to propose a device and protocol for sampling intact soil monoliths (60 x 30 x 22 cm(3), length, width, depth [LWD]) without heavy machinery. This is achieved by a modular design with removable top and bottom lid and a protocol of cutting the soil and replacing the affected bottom soil with a drainage layer of glass beads. The device allows the application of artificial rainfall events with simultaneous highly resolved quantification of infiltration excess overland flow and drainage discharge. It is designed to facilitate the collection of samples for physical, biological, and chemical analyses that fulfill cleanliness standards for organic contaminant analysis at trace levels using only poorly reactive stainless steel and glass materials. Testing of the device was performed by measuring the transfer of the antiparasitic drug ivermectin (IVM) through and over a silt-loam pasture soil. This test case illustrates how the device can be used to gain valuable information on the transfer of trace organic contaminants through topsoils.
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Hachgenei, N., Vaury, V., Nord, G., Spadini, L., & Duwig, C. (2022). Faster And More Precise Isotopic Water Analysis Of Discrete Samples By predicting the repetitions' asymptote instead of averaging last values. Methodsx, 9.
Abstract: Water stable isotope analysis using Cavity Ring-Down Spectroscopy (CRDS) has a strong between-sample memory effect. The classic approach to correct this memory effect is to inject the sample at least 6 times and ignore the first two to three injections. The average of the remaining injections is then used as measured value. This is in many cases insufficient to completely compensate the memory effect. We propose a simple approach to correct this memory effect by predicting the asymptote of consecutive repeated injections instead of averaging over them. The asymptote is predicted by fitting a y = a/x + b relation to the sample repetitions and keeping b as measured value. This allows to save analysis time by doing less injections while gaining precision. We provide a Python program applying this method and describe the steps necessary to implement this method in any other programming language. We also show validation data comparing this method to the classical method of averaging over the last couple of injections. The validation suggests a gain in time of a factor two while gaining in precision at the same time. The method does not have any specific requirements for the order of analysis and can therefore also be applied to an existing set of analyzes in retrospect. We fit a simple y = a/x + b relation to the sample repetitions of Picarro L2130-i isotopic water analyzer, in order to keep the asymptote (b) as measured value instead of using the average over the last couple of measurements. This allows a higher precision in the measured value with less repetitions of the injection saving precious time during analysis. We provide a sample code using Python, but generally this method is easy to implement in any automated data treatment protocol. (C) 2022 The Author(s). Published by Elsevier B.V.
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Haddad, H., Jodeau, M., Legout, C., Antoine, G., & Droppo, I. G. (2022). Spatial Variability Of The Erodibility Of Fine Sediments Deposited In two alpine gravel-bed rivers: The Isere and Galabre. Catena, 2122.
Abstract: In mountainous environments, high suspended sediment load during runoff or dam flushing events can lead to important amounts of fine deposits in gravel bed rivers. Fine sediment deposits may contribute to bar elevation, riparian vegetation growth and consequently to bar stabilization. Despite their contribution to the morphodynamic of mountain rivers, the erosion properties of fine sediments in this context is not fully understood.& nbsp;In order to investigate the dynamics of re-suspension of these deposits, field monitoring campaigns were performed to explore both the spatial variability and the controlling factors of the erodibility of fine deposits. A cohesive strength-meter (CSM), along with moisture, grain sizes, geographical position and elevation were used to evaluate both the critical bed shear stress for erosion and erosion rate of fine sediment deposits in two rivers of the French Alps: the Ise`re and Galabre.& nbsp;The results highlight a large variety of fine sediment deposition areas, which are discontinuous compared to those in estuaries and lowland rivers. A high spatial variability of erodibility was observed on the reach, the bar and the metric scale. While no upstream-downstream trend was observed at the scale of both studied reaches, the locations of the deposits, elevation from the river surface and their moisture were inter-related variables and with the highest correlations to erodibility. Measurements showed that both dry and humid deposits located at the highest and lowest elevation from the river surface respectively, were more easily eroded than intermediate deposits with medium moisture.
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Haddad, H., Legout, C., & Jodeau, M. (2022). Spatial Variability Of Erodibility Of Fine Sediments Deposited In Gravel River Beds: From Field Measurements To 2D Numerical Models. Journal Of Soils And Sediments, .
Abstract: Purposegravel-Bed Rivers Can Store Significant Amounts Of Fine Sediments, In The Gravel Matrix Or At The Bar Surface. The Contribution Of The Latter To Suspended Sediment Fluxes Depends On Their Erodibility Which Is Highly Variable Spatially. The Sensitivity Induced By This Spatial Variability On Outputs Of A 2D Hydro-Sedimentary Numerical Model Was Investigated And Recommendations For In Situ Erodibility Measurement Strategy Were Provided.Methodsthe Spatial Variability Of Fine Sediment Erodibility Was Determined Using The Cohesive Strength Meter (Csm) Device In A 1-Km-Long River Reach Of The Galabre River In The Southern French Alps. A 2D Hydro-Sedimentary Numerical Model Was Built On The Monitored Reach Displaying Three Deposit Zones With Distinct Erodibility Values. The Sensitivity Of The Modeled Eroded Masses To Sediment Erodibility Variability Was Assessed Through Ten Distinct Sediment Erodibility Settings And Three Schematic Flood Events, Based On The In Situ Monitoring Of The River.Results And Discussionthe Spatial Variability Of Fine Sediment Deposit Erodibility Was Significant. Marginal Deposits Were More Resistant Than Superficial Or Water-Saturated Ones. The Sensitivity Of The Modeled Eroded Mass To Erodibility Parameters Was Different Depending On The Set Of Measurements Used. When Considering The Entire Dataset, Which Exhaustively Characterizes The Fine Sediment Deposits, The Numerical Sensitivity Was Relatively Low. On The Other Hand, When A Partial Set Of Measurements Outside The Quartiles Was Considered, The Sensitivity Was More Significant Leading To Large Differences In Eroded Masses Between Spatially Distributed And Spatially Averaged Settings. Using Bootstrap Sampling, We Recommended Making 15 To 20 Measurements In Marginal And Superficial Zones To Adequately Capture The Distribution Of Erodibility.Conclusionsthis Work Provided Insight On The Spatial Variability Of Erodibility And The Sensitivity Induced In 2D Numerical Modeling Of Fine Sediments. The Proposed Methodology Could Be Applied To Other Environments (E.G., Reservoirs, Estuaries, Or Lowland Rivers) In Order To Adapt The Monitoring And Numerical Modeling Strategies.
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Hamal, K., Ghimire, S. K., Khadka, A., Dawadi, B., & Sharma, S. (2022). Interannual Variability Of Spring Fire In Southern Nepal. Atmospheric Science Letters, .
Abstract: Nepal is highly vulnerable to climate change with increased fire occurrences and fire burned areas in recent years; therefore, we accessed the climatic drivers for its variability using fire burned areas product of Moderate Resolution Imaging Spectroradiometer (MODIS) from 2001 and 2020. The peak fire burned areas were observed in the spring season (similar to 91%) from March to May, especially higher in the lowlands of the western and central parts. At the inter-annual timescale, low precipitation, humidity, soil moisture, and high temperature supported the existence of spring fire. Combining these factors induces drought conditions, enhancing evapotranspiration from vegetation and providing more combustible fuels. Furthermore, the El Nino phase in the central-eastern Pacific Ocean is related to the weakened westerly moisture transport and moisture divergence that creates dry and warm conditions leading to increased fire activities. Thus, this study could be helpful for preparedness, management, and policy-making to limit the multi-dimensional losses in the ecosystem and society due to fire.
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Han, C., Burn, L. J., Vallelonga, P., Do Hur, S., Boutron, C. F., Han, Y., et al. (2022). Lead Isotopic Constraints On The Provenance Of Antarctic Dust And Atmospheric Circulation Patterns Prior to the Mid-Brunhes Event (similar to 430 kyr ago). Molecules, 272(131).
Abstract: A lead (Pb) isotopic record, covering the two oldest glacial-interglacial cycles (similar to 572 to 801 kyr ago) characterized by lukewarm interglacials in the European Project for Ice Coring in Antarctica Dome C ice core, provides evidence for dust provenance in central East Antarctic ice prior to the Mid-Brunhes Event (MBE), similar to 430 kyr ago. Combined with published post-MBE data, distinct isotopic compositions, coupled with isotope mixing model results, suggest Patagonia/Tierra del Fuego (TdF) as the most important sources of dust during both pre-MBE and post-MBE cold and intermediate glacial periods. During interglacials, central-western Argentina emerges as a major contributor, resulting from reduced dust supply from Patagonia/TdF after the MBE, contrasting to the persistent dominance of dust from Patagonia/TdF before the MBE. The data also show a small fraction of volcanic Pb transferred from extra-Antarctic volcanoes during post-MBE interglacials, as opposed to abundant transfer prior to the MBE. These differences are most likely attributed to the enhanced wet removal efficiency with the hydrological cycle intensified over the Southern Ocean, associated with a poleward shift of the southern westerly winds (SWW) during warmer post-MBE interglacials, and vice versa during cooler pre-MBE ones. Our results highlight sensitive responses of the SWW and the associated atmospheric conditions to stepwise Antarctic warming.
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Haruna, A., Blanchet, J., & Favre, A. C. (2022). Performance-Based Comparison Of Regionalization Methods To Improve The at-site estimates of daily precipitation. Hydrology And Earth System Sciences, 262(101), 2797–2811.
Abstract: In this article, we compare the performance of three regionalization approaches in improving the at-site estimates of daily precipitation. The first method is built on the idea of conventional RFA (regional frequency analysis) but is based on a fast algorithm that defines distinct homogeneous regions relying on their upper-tail similarity. It uses only the precipitation data at hand without the need for any additional covariate. The second is based on the region-of-influence (ROI) approach in which neighborhoods, containing similar sites, are defined for each station. The third is a spatial method that adopts generalized additive model (GAM) forms for the model parameters. In line with our goal of modeling the whole range of positive precipitation, the chosen marginal distribution model is the extended generalized Pareto distribution (EGPD) to which we apply the three methods. We consider a dense network composed of 1176 daily stations located within Switzerland and in neighboring countries. We compute different criteria to assess the models' performance in the bulk of the distribution and the upper tail. The results show that all the regional methods offered improved robustness over the local EGPD model. While the GAM method is more robust and reliable in the upper tail, the ROI method is better in the bulk of the distribution.
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Haruna, A., Garambois, P., Roux, H., Javelle, P., & Jay-Allemand, M. (2022). Does Flash Flood Model Performance Increase With Complexity? Signature And Sensitivity-Based Comparison Of Conceptual And Process-Oriented Models On French Mediterranean Cases. Hydrology, 9(8).
Abstract: We Compare Three Hydrological Models Of Different Complexities, Gr4H (Lumped, Continuous), Smash (Distributed, Continuous), And Marine (Distributed, Event-Based), For Mediterranean Flash Flood Modeling. The Objective Was To Understand How Differently They Simulate The Catchment'S Behavior, In Terms Of Outlet Discharge And Internal Dynamics, And How These Can Help To Improve The Relevance Of The Models. The Methodology Involved Global Sensitivity Analysis, Calibration/Validation, And Signature Comparison At The Event Scale With Good Performances. For All Models, We Found Transfer Parameters To Be Sensitive In The Case Of Gardon And Production Parameters In The Case Of Ardeche. The Non-Conservative Flow Component Of Gr4H Was Found To Be Sensitive And Could Benefit The Distributed Models. At The Event Scale, The Process-Based Marine Model At Finer Resolution Outperformed The Two Continuous Hourly Models At Flood Peak And Its Timing. Smash, Followed By Gr4H, Performed Better In The Volume Of Water Exported. Using The Operational Surface Model Sim2 To Benchmark The Soil Moisture Simulated By The Three Models, Marine (Initialized With Sim1) Emerged As The Most Accurate. Gr4H Followed Closely, While Smash Was The Least Accurate. Flexible Modeling And Regionalization Should Be Developed Based On Multi-Source Signatures And Worldwide Physiographic Databases.
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Herbaut, C., Houssais, M. N., Blaizot, A. C., & Molines, J. M. (2022). A Role For The Ocean In The Winter Sea Ice Distribution North Of Svalbard. Journal Of Geophysical Research-Oceans, 1271(6).
Abstract: The ocean is suggested to play a major role in the ongoing winter decay of the sea ice cover in the western Eurasian Basin. Using a high-resolution sea ice-ocean model, we investigate the processes influencing the ice-ocean interactions in winter in the waters north of Svalbard, with a particular focus on those contributing to sea ice melt events of large amplitude. These short term events, lasting 5-10 days, are associated with locally large melt rates mostly found along the pathway of the Atlantic Water. The sum of all these events over the simulation period is found to contribute 40% of the total winter melt. Episodes of strong surface winds, occasionally associated with enhanced velocity shear at the mixed layer base, can trigger enhanced entrainment of Atlantic Water through the relatively shallow upper thermocline in the Atlantic Water boundary current, leading to substantial ocean heat transfer to the sea ice. In some cases, strengthening of the boundary current also contributes to fueling the heat transfer to the ice. Another type of large melt event, not linked to increased ocean vertical heat flux but due to ice being advected over warm surface waters, is also identified, sometimes associated with episodes of ice close-up. Sea ice budget calculations show that, overall, large melt events contribute significantly to the eastward retreat of the winter marginal ice zone on the upper slope east of Svalbard while episodes of northward advection of ice largely dominate the ice edge retreat over the shelf north of Svalbard.
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Heredia, C., Guedron, S., Point, D., Perrot, V., Campillo, S., Verin, C., et al. (2022). Anthropogenic Eutrophication Of Lake Titicaca (Bolivia) Revealed By Carbon And Nitrogen Stable Isotopes Fingerprinting. Science Of The Total Environment, 8458.
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Hoang, C., Magand, O., Brioude, J., Dimuro, A., Brunet, C., Ah-Peng, C., et al. (2022). Probing The Limits Of Sampling Gaseous Elemental Mercury Passively In The Remote Atmosphere. Environmental Science-Atmospheres, .
Abstract: Reliably Recording Very Low Ambient Concentrations Of Gaseous Elemental Mercury (Gem) In Remote Regions Is Often Required, For Example In The Context Of Evaluating How Effective The Minamata Convention Is In Reducing Global Hg Emissions. However, Sampling Over Extended Periods Of Time At Sites That Are Difficult To Access Can Be Very Challenging. In Order To Establish What Role Inexpensive And Easy-To-Use Passive Air Samplers May Play In This Regard, We Deployed A Sampler Using A Radiello Diffusive Barrier And Activated Carbon Sorbent For Periods Of Up To Three Years And With Sampling Periods Ranging From One To Three Months In Some Of The Most Extreme, Remote And Challenging Global Environments: At Concordia Station On The Antarctic Plateau, On Amsterdam Island In The Remote Southern Indian Ocean And At Several Sites On The Tropical Island Of La Reunion. The Ability To Reliably Record The Gem Concentrations At These Sites Was Strongly Influenced By The Size Of The Sequestered Amount Of Mercury Relative To The Extent And Variability Of The Contamination Of Field Blank Samples. In Some Cases, Acceptably Low And Consistent Field Blank Contamination Could Only Be Achieved By Storing Samplers In Sealed Glass Jars During Transport And Storage. The Size Of The Sequestered Amount Is Easily Increased By Extending Deployment Times, And The Experience Of The Current Study Suggests That Deployment Periods In Excess Of Two Months Are Advisable. Sampling In Antarctica Was Compromised By The Extreme Low Temperatures, Which Caused Unknown Sampling Rates, Hoar Frost Accumulation, Material Failure And Potential Failure Of Storage Seals. While Good Agreement With Gem Concentrations Measured With An Active Sampler Was Noted On Amsterdam Island, The Passive Sampler Derived Levels At The Maido Observatory In La Reunion Were Notably Higher Than Concentrations Measured Simultaneously With A Tekran Vapour Analyzer, Which Was Possibly Related To Sampling Rates Being Temporarily Elevated At The Very Beginning Of Deployment At Low Gem Concentrations.
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Hogg, A. M., Penduff, T., Close, S. E., Dewar, W. K., Constantinou, N. C., & Martinez-Moreno, J. (2022). Circumpolar Variations In The Chaotic Nature Of Southern Ocean Eddy Dynamics. Journal Of Geophysical Research-Oceans, 1271(5).
Abstract: Circulation in the Southern Ocean is unique. The strong wind stress forcing and buoyancy fluxes, in concert with the lack of continental boundaries, conspire to drive the Antarctic Circumpolar Current replete with an intense eddy field. The effect of Southern Ocean eddies on the ocean circulation is significant-they modulate the momentum balance of the zonal flow, and the meridional transport of tracers and mass. The strength of the eddy field is controlled by a combination of forcing (primarily thought to be wind stress) and intrinsic, chaotic, variability associated with the turbulent flow field itself. Here, we present results from an eddy-permitting ensemble of ocean model simulations to investigate the relative contribution of forced and intrinsic processes in governing the variability of Southern Ocean eddy kinetic energy. We find that variations of the eddy field are mostly random, even on longer (interannual) timescales. Where correlations between the wind stress forcing and the eddy field exist, these interactions are dominated by two distinct timescales-a fast baroclinic instability response; and a multi-year process owing to feedback between bathymetry and the mean flow. These results suggest that understanding Southern Ocean eddy dynamics and its larger-scale impacts requires an ensemble approach to eliminate intrinsic variability, and therefore may not yield robust conclusions from observations alone.
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Hogg, A. M., Penduff, T., Close, S. E., Dewar, W. K., Constantinou, N. C., & Martinez-Moreno, J. (2022). Circumpolar Variations In The Chaotic Nature Of Southern Ocean Eddy Dynamics. Journal Of Geophysical Research-Oceans, 1271(5).
Abstract: Circulation in the Southern Ocean is unique. The strong wind stress forcing and buoyancy fluxes, in concert with the lack of continental boundaries, conspire to drive the Antarctic Circumpolar Current replete with an intense eddy field. The effect of Southern Ocean eddies on the ocean circulation is significant-they modulate the momentum balance of the zonal flow, and the meridional transport of tracers and mass. The strength of the eddy field is controlled by a combination of forcing (primarily thought to be wind stress) and intrinsic, chaotic, variability associated with the turbulent flow field itself. Here, we present results from an eddy-permitting ensemble of ocean model simulations to investigate the relative contribution of forced and intrinsic processes in governing the variability of Southern Ocean eddy kinetic energy. We find that variations of the eddy field are mostly random, even on longer (interannual) timescales. Where correlations between the wind stress forcing and the eddy field exist, these interactions are dominated by two distinct timescales-a fast baroclinic instability response; and a multi-year process owing to feedback between bathymetry and the mean flow. These results suggest that understanding Southern Ocean eddy dynamics and its larger-scale impacts requires an ensemble approach to eliminate intrinsic variability, and therefore may not yield robust conclusions from observations alone.
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Hounsinou, M., Mamadou, O., Wudba, M., Kounouhewa, B., & Cohard, J. M. (2022). Integral turbulence characteristics over a clear woodland forest in northern Benin (West Africa). Atmospheric Research, 2682.
Abstract: This study aims at investigating whether the Integral Turbulence Characteristics (ITC) obey the Monin-Obukhov Similarity Theory (MOST) above a forest site in a Sudanian climate, and at identifying the appropriate ITC models for this ecosystem. Data were collected from a 18 m tower equipped with an Eddy Covariance system, above the clear forest close to Bellefoungou's village, Northwest of Benin, West Africa. The turbulence intensity parameters calculated for five years and half, were analyzed according to wind speed, stability conditions and seasons. From their relationships with the stability parameter, data driven models were then obtained by the nonlinear least squares. The results showed that, all similarity functions follow MOST with a 1/3 power law whatever the stratification of the atmosphere during all the seasons excepted the temperature which had a parabolic shape in near neutral condition (-0.05 < zeta < 0.1). A seasonal dependence of all ITCs was evidenced under stable conditions. We also showed that the heat transfer is relatively more efficient than H2O transfer under both stability conditions. The established temperature and CO2 similarity models are found to be closer, and for some given stratification conditions, to those already existing in literature. But a noteworthy finding is that the models often used to assign a quality criterion to turbulent fluxes showed an overestimation relatively to those established 'locally' for u and w through all atmospheric stratification.
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Hugonnet, R., Brun, F., Berthier, E., Dehecq, A., Mannerfelt, E., Eckert, N., et al. (2022). Uncertainty Analysis Of Digital Elevation Models By Spatial Inference From Stable Terrain. Ieee Journal Of Selected Topics In Applied Earth Observations And Remote Sensing, 151, 6456–6472.
Abstract: The Monitoring Of Earth'S And Planetary Surface Elevations At Larger And Finer Scales Is Rapidly Progressing Through The Increasing Availability And Resolution Of Digital Elevation Models (Dems). Surface Elevation Observations Are Being Used Across An Expanding Range Of Fields To Study Topographical Attributes And Their Changes Over Time, Notably In Glaciology, Hydrology, Volcanology, Seismology, Forestry, And Geomorphology. However, Dems Frequently Contain Large-Scale Instrument Noise And Varying Vertical Precision That Lead To Complex Patterns Of Errors. Here, We Present A Validated Statistical Workflow To Estimate, Model, And Propagate Uncertainties In Dems. We Review The State-Of-The-Art Of Dem Accuracy And Precision Analyses, And Define A Conceptual Framework To Consistently Address Those. We Show How To Characterize Dem Precision By Quantifying The Heteroscedasticity Of Elevation Measurements, I.E., Varying Vertical Precision With Terrain- Or Sensor-Dependent Variables, And The Spatial Correlation Of Errors That Can Occur Across Multiple Spatial Scales. With The Increasing Availability Of High-Precision Observations, Our Workflow Based On Independent Elevation Data Acquired On Stable Terrain Can Be Applied Almost Anywhere On Earth. We Illustrate How To Propagate Uncertainties For Both Pixel-Scale And Spatial Elevation Derivatives, Using Terrain Slope And Glacier Volume Changes As Examples. We Find That Uncertainties In Dems Are Largely Underestimated In The Literature, And Advocate That New Metrics Of Dem Precision Are Essential To Ensure The Reliability Of Future Land Elevation Assessments.
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Huot, P. V., Kittel, C., Fichefet, T., Jourdain, N. C., & Fettweis, X. (2022). Effects of ocean mesoscale eddies on atmosphere-sea ice-ocean interactions off Adelie Land, East Antarctica. Climate Dynamics, .
Abstract: Heat and momentum exchanges at the Southern Ocean surface are crucial for the Earth's Climate, but the importance of the small-scale spatial variability of these surface fluxes is poorly understood. Here, we explore how small-scale heterogeneities of the surface conditions due in particular to ocean eddies affect the atmosphere-sea ice-ocean interactions off Adelie Land, in East Antarctica. To this end, we use a high-resolution regional atmosphere-sea ice-ocean coupled model based on the NEMO-LIM and MAR models. We explore how the atmosphere responds to small-scale heterogeneity of the ocean or sea ice surface conditions, how eddies affect the sea ice and atmosphere, and how the eddy-driven surface fluxes impact the heat, freshwater, and momentum budget of the ocean. The atmosphere is found to be more sensitive to small-scale surface temperature gradients above the ice-covered than above the ice-free ocean. Sea ice concentration is found to be weaker above anticyclonic than cyclonic eddies due to increased sea ice melting or freezing (0.8 cm/day) partly compensated by sea ice convergence or divergence. The imprint of ice-free eddies on the atmosphere is weak, but in the presence of sea ice, air warming (+ 0.3 degrees C) and wind intensification (+ 0.1 m/s) are found above anticyclonic eddies, while cyclonic eddies have the opposite effects. Removing the interactions of eddies with the sea ice or atmosphere does not affect the total sea ice volume, but increases the ocean kinetic energy by 8% and weakens northward advection of sea ice, leading to a 15% decrease in freshwater flux north of 62.5 degrees S and weaker ocean restratification.
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Jacq, K., Rapuc, W., Benoit, A., Coquin, D., Fanget, B., Perrette, Y., et al. (2022). Sedimentary structure discrimination with hyperspectral imaging in sediment cores. Science Of The Total Environment, 8178.
Abstract: Hyperspectral imaging (HSI) isa non-destructive, high-resolution imaging technique that is currently under significant development for analyzing geological areas with remote devices or natural samples in a laboratory. In both cases, the hyperspectral image provides several sedimentary structures that must be separated to temporally and spatially de-scribe the sample. Sediment sequences are composed of successive deposits (strata, homogenite, flood) that are visible depending on sample properties. The classical methods to identify them are time-consuming, have a low spatial reso-lution (millimeters) and are generally based on naked-eye counting. In this study, we compare several supervised clas-sification algorithms to discriminate sedimentological structures in lake sediments. Instantaneous events in lake sediments are generally linked to extreme geodynamical events (e.g., floods, earthquakes), so their identification and counting are essential to understand long-term fluctuations and improve hazard assessments. Identification and counting are done by reconstructing a chronicle of event layer occurrence, including estimation of deposit thicknesses. Here, we applied two hyperspectral imaging sensors (Visible Near-Infrared, VNIR, 60 μm, 400-1000 nm; Short Wave Infrared, SWIR, 200 μm, 1000-2500 nm) on three sediment cores from different lake systems. We highlight that the SWIR sensor is the optimal one for creating robust classification models with discriminant analyses (prediction accu-racies of 0.87-0.98). Indeed, the VNIR sensor is impacted by the surface reliefs and structures that are not in the learn-ing set, which causes mis-classification. These observations are also valid for the combined sensor (VNIR-SWIR) and the RGB images. Several spatial and spectral pre-processing were also compared and enabled one to highlight discriminant information specific to a sample and a sensor. These works show that the combined use of hyperspectral imaging and machine learning improves the characterization of sedimentary structures compared to conventional methods.
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Jamet, Q., Leroux, S., Dewar, W., Penduff, T., Le Sommer, J., Molines, J., et al. (2022). Non-Local Eddy-Mean Kinetic Energy Transfers In Submesoscale-Permitting Ensemble Simulations. Journal Of Advances In Modeling Earth Systems, 141(101).
Abstract: Understanding Processes Associated With Eddy-Mean Flow Interactions Helps Our Interpretation Of Ocean Energetics, And Guides The Development Of Parameterizations. Here, We Focus On The Non-Local Nature Of Kinetic Energy (Ke) Transfers Between Mean And Turbulent Reservoirs. Transfers Are Interpreted As Non-Local When The Energy Extracted From The Mean Flow Does Not Locally Sustain An Growth Of Energy In The Turbulent Flow, Or Vice Versa. The Novelty Of Our Approach Is To Use Ensemble Statistics To Define The Mean And The Turbulent Flow. Based On Ke Budget Considerations, We First Rationalize The Eddy-Mean Separation In The Ensemble Framework, And Discuss The Interpretation Of A Mean Flow < U > Driven By The Prescribed (Surface And Boundary) Forcing And A Turbulent Flow U' Driven By Non-Linear Dynamics Sensitive To Initial Conditions. We Then Analyze 120-Day Long, 20-Member Ensemble Simulations Of The Western Mediterranean Basin Run At 1/60 Degrees Resolution. Our Main Contribution Is To Recognize The Prominent Contribution Of The Cross Energy Term < U(H)> . U(H)' To Explain Non-Local Energy Transfers, Which Provides A Strong Constraint On The Horizontal Organization Of Eddy-Mean Flow Ke Transfers Since The Cross Energy Term Vanishes Identically For Perturbations (U(H)') Orthogonal To The Mean Flow (< U(H)>). We Also Highlight The Prominent Contribution Of Vertical Turbulent Fluxes For Energy Transfers Within The Surface Mixed Layer. Analyzing The Scale Dependence Of Non-Local Energy Transfers Supports The Local Approximation Usually Made In The Development Of Meso-Scale, Energy-Aware Parameterizations For Non-Eddying Models, But Points Out To The Necessity Of Accounting For Non-Local Dynamics In The Meso-To-Submeso Scale Range. Plain Language Summary The Ocean Constantly Exchanges Energy Between Its Mean And Its Turbulent Reservoirs. However, We Are Still Lacking A Clear Understanding Of Eddy-Mean Flow Interactions, Which Limits Our Ability To Represent Them In Numerical Ocean Simulations That Require Turbulent Closures. In Particular, It Has Been Recently Shown That Instabilities Of Midlatitude Jets Do Not Necessarily Sustain The Growth Of Turbulent Eddies Locally. Instead, The Energy Released By The Jet Can Be Transported Over Significant Distances To Either Sustain Turbulence Or To Reinforce The Jet. Here, We Analyze Model Outputs Of Submesoscale-Permitting (Horizontal Resolution Of 1-2 Km) Ensemble Simulations Of The Western Mediterranean Basin With The View Of Better Understanding This Non-Local Dynamics. Starting From 20 Initial Conditions Perturbed By Small, Independent Perturbations, We Analyze The Development Of The Ensemble Spread During 120-Days Long Simulations Exposed To Identical Forcing. We Investigate The Spatiotemporal Structure Of Eddy-Mean Flow Interactions Through Their Kinetic Energy Expression. Our Main Contribution Is To Highlight Turbulent Fluxes Of The Cross Energy Term As A Driving Mechanism To Explain Non-Local Dynamics, A Process That Need To Be Accounted For In The Development Of Submesoscale Parametrizations.
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Jiang, Z., Savarino, J., Alexander, B., Erbland, J., Jaffrezo, J. L., & Geng, L. (2022). Impacts Of Post-Depositional Processing On Nitrate Isotopes In The Snow and the overlying atmosphere at Summit, Greenland. Cryosphere, 161(7), 2709–2724.
Abstract: The effect of post-depositional processing on the preservation of snow nitrate isotopes at Summit, Greenland, remains a subject of debate and is relevant to the quantitative interpretation of ice-core nitrate (isotopic) records at high snow accumulation sites. Here we present the first year-round observations of atmospheric nitrate and its isotopic compositions at Summit and compare them with published surface snow and snowpack observations. The atmospheric delta N-15(NO3-) remained negative throughout the year, ranging from -3.1 parts per thousand to -47.9 parts per thousand with a mean of (-14.8 +/- 7.3)parts per thousand (n = 54), and displayed minima in spring which are distinct from the observed spring delta N-15(NO3-) maxima in snowpack. The spring average atmospheric delta N-15(NO3-) was (-17.9 +/- 8.3) parts per thousand (n = 21), significantly depleted compared to the snowpack spring average of (4.6 +/- 2.1)parts per thousand, while the surface snow delta N-15(NO3-) of (-6.8 +/- 0.5)parts per thousand was in between the atmosphere and the snowpack. The differences in atmospheric, surface snow and snowpack delta N-15(NO3-) are best explained by the photo-driven post-depositional processing of snow nitrate, with potential contributions from fractionation during nitrate deposition. In contrast to delta N-15(NO3-) the atmospheric Delta O-1(7)(NO3-) was of a similar seasonal pattern and magnitude of change to that in the snowpack, suggesting little to no changes in Delta O-1(7)(NO3-) from photolysis, consistent with previous modeling results. The atmospheric delta O-18(NO3-) varied similarly to atmospheric Delta O-1(7)(NO3-), with summer low and winter high values. However, the difference between atmospheric and snow delta O-18(NO3-) was larger than that of Delta O-17(NO3-). We found a strong correlation between atmospheric delta O-18(NO3-) and Delta O-17(NO3-) that is very similar to previous measurements for surface snow at Summit, suggesting that atmospheric delta O-18(NO3-) versus Delta O-17(NO3-) relationships were conserved during deposition. However, we found the linear relationships between delta O-18 and Delta O-17(NO3-) were significantly different for snowpack compared to atmospheric samples. This likely suggests the oxygen isotopes are also affected before preservation in the snow at Summit, but the degree of change for delta O-18(NO3-) should be larger than that of Delta O-17(NO3-). This is because photolysis is a massdependent process that would directly affect delta O-18(NO3-) in snow but not Delta O-17(NO3-) as the latter is a mass-independent signal. Although there were uncertainties associated with the complied dataset, the results suggested that post-depositional processing at Summit can induce changes in nitrate isotopes, especially delta N-15(NO3-), consistent with a previous modeling study. This reinforces the importance of understanding the effects of post-depositional processing before ice-core nitrate isotope interpretation, even for sites with relatively high snow accumulation rates.
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Jomelli, V., Swingedouw, D., Vuille, M., Favier, V., Goehring, B., Shakun, J., et al. (2022). In-phase millennial-scale glacier changes in the tropics and North Atlantic regions during the Holocene. Nature Communications, 131(1).
Abstract: Glaciers showed a similar evolution in Greenland, Europe, the US and the tropical Andes during the Holocene. The authors propose the Atlantic Meridional Ocean Overturning Circulation as a key driver of this trend. Based on new and published cosmic-ray exposure chronologies, we show that glacier extent in the tropical Andes and the north Atlantic regions (TANAR) varied in-phase on millennial timescales during the Holocene, distinct from other regions. Glaciers experienced an early Holocene maximum extent, followed by a strong mid-Holocene retreat and a re-advance in the late Holocene. We further explore the potential forcing of TANAR glacier variations using transient climate simulations. Since the Atlantic Meridional Overturning Circulation (AMOC) evolution is poorly represented in these transient simulations, we develop a semi-empirical model to estimate the “AMOC-corrected” temperature and precipitation footprint at regional scales. We show that variations in the AMOC strength during the Holocene are consistent with the observed glacier changes. Our findings highlight the need to better constrain past AMOC behavior, as it may be an important driver of TANAR glacier variations during the Holocene, superimposed on other forcing mechanisms.
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Jouberton, A., Shaw, T., Miles, E., Mccarthy, M., Fugger, S., Ren, S., et al. (2022). Warming-Induced Monsoon Precipitation Phase Change Intensifies Glacier Mass Loss In The Southeastern Tibetan Plateau. Proceedings Of The National Academy Of Sciences Of The United States Of America, .
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Jouberton, A., Shaw, T., Miles, E., Mccarthy, M., Fugger, S., Ren, S., et al. (2022). Warming-Induced Monsoon Precipitation Phase Change Intensifies Glacier Mass Loss In The Southeastern Tibetan Plateau. Proceedings Of The National Academy Of Sciences Of The United States Of America, 1191(373).
Abstract: Glaciers Are Key Components Of The Mountain Water Towers Of Asia And Are Vital For Downstream Domestic, Agricultural, And Industrial Uses. The Glacier Mass Loss Rate Over The Southeastern Tibetan Plateau Is Among The Highest In Asia And Has Accelerated In Recent Decades. This Acceleration Has Been Attributed To Increased Warming, But The Mechanisms Behind These Glaciers' High Sensitivity To Warming Remain Unclear, While The Influence Of Changes In Precipitation Over The Past Decades Is Poorly Quantified. Here, We Reconstruct Glacier Mass Changes And Catchment Runoff Since 1975 At A Benchmark Glacier, Parlung No. 4, To Shed Light On The Drivers Of Recent Mass Losses For The Monsoonal, Spring-Accumulation Glaciers Of The Tibetan Plateau. Our Modeling Demonstrates How A Temperature Increase (Mean Of 0.39 Degrees C Center Dot Dec(-1) Since 1990) Has Accelerated Mass Loss Rates By Altering Both The Ablation And Accumulation Regimes In A Complexmanner. The Majority Of The Post-2000 Mass Loss Occurred During Themonsoon Months, Caused By Simultaneous Decreases In The Solid Precipitation Ratio (From 0.70 To 0.56) And Precipitation Amount (-10%), Leading To Reduced Monsoon Accumulation (-26%). Higher Solid Precipitation In Spring (+18%) During The Last Two Decades Was Increasingly Important In Mitigating Glacier Mass Loss By Providing Mass To The Glacier And Protecting It From Melting In The Early Monsoon. With Bare Ice Exposed To Warmer Temperatures For Longer Periods, Icemelt And Catchment Discharge Have Unsustainably Intensified Since The Start Of The 21St Century, Raising Concerns For Long-Term Water Supply And Hazard Occurrence In The Region.
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Jourdain, N., Mathiot, P., Burgard, C., Caillet, J., & Kittel, C. (2022). Ice Shelf Basal Melt Rates In The Amundsen Sea At The End Of The 21St Century. Geophysical Research Letters, 494(222).
Abstract: Antarctic Ice Sheet Projections Show The Highest Sensitivity To Increased Basal Melting In The Amundsen Sea. However, Little Is Known About The Processes That Control Future Increase In Melt Rates. We Build An Ensemble Of Three Ocean-Sea-Ice-Ice-Shelf Simulations For Both The Recent Decades And The Late 21St Century, Constrained By Regional Atmosphere Simulations And The Multi-Model Mean Climate Change Of The Fifth Climate Model Intercomparison Project Under The Rcp8.5 Scenario. The Ice-Shelf Melt Rates Are Typically Multiplied By 1.4-2.2 From Present Day To Future, For A Total Basal Mass Loss Increased By 346 Gt Yr(-1) On Average. This Is Equally Explained By Advection Of Warmer Water From Remote Locations And Regional Changes In Ekman Downwelling And In The Ice-Shelf Melt-Induced Circulation, While Increased Iceberg Melt Plays No Significant Role. Our Simulations Suggest That High-End Melt Projections Previously Used To Constrain Recent Sea Level Projections May Have Been Significantly Overestimated.
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Junquas, C., Heredia, M. B., Condom, T., Ruiz-Hernandez, J. C., Campozano, L., Dudhia, J., et al. (2022). Regional climate modeling of the diurnal cycle of precipitation and associated atmospheric circulation patterns over an Andean glacier region (Antisana, Ecuador). Climate Dynamics, .
Abstract: A multi-experiment ensemble is performed using the WRF (Weather Research and Forecasting) model at high spatial resolution (1 km) over the Antisana glacier region (Ecuador), during the year 2005. Our goal is to identify the best model configurations to simulate atmospheric processes at diurnal and seasonal scales. The model is able to reproduce the complex zonal gradient of precipitation between the wet Amazon and the drier inter-Andean region. The main precipitation biases are (i) an overestimation in the afternoon (up to 6 mm/day) in the Antisana region related to local surface circulation patterns and (ii) a nighttime overestimation (up to 20 mm/day) in the Andes-Amazon transition zone associated with the regional circulation. Changing the microphysics scheme and/or the cumulus scheme primarily affect nighttime processes, while changing the topography forcing and activating slope radiation and shading options mostly affects afternoon processes. An adequate choice of the model configuration allows a correct representation of the diurnal cycle of precipitation, and in particular: (i) the mid-level easterly regional flow, (ii) the local moisture transport along and across the valleys, and (iii) the orographic mountain waves on the Antisana summit. For this specific area and year, the best configuration retained defined as “dSRTM_LRad” shows nighttime (daytime) precipitation biases smaller than 2 mm/day (3 mm/day); it is based on non-smoothed SRTM digital elevation model (dSRTM), Lin Purdue microphysics (L), and slope and shading radiation options (Rad). This 1-km resolution configuration requires the activation of the cumulus scheme, that improves the regional nighttime convection induced by the easterly regional flow on the Amazon-Andes transition region. It allows also a realistic strengthening of the daytime upward moisture transport. This study demonstrates that in the Antisana region, 1 km is a resolution still too coarse to deactivate cumulus schemes for a correct representation of cloud convection.
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Junqueira, R., Viola, M. R., Amorim, J. D., Wongchuig, S. C., de Mello, C. R., Vieira, M., et al. (2022). Hydrological Retrospective And Historical Drought Analysis In A Brazilian Savanna Basin. Water, 141(141).
Abstract: Analyzing historical droughts is essential to improve the assessment of future hydrological risks and to understand the effects of climate variability on streamflow. However, prolonged and consistent hydrological time series are scarce in the Brazilian savanna region. This study aimed to analyze the performance of climate reanalysis products in precipitation estimation, hydrological modeling, and historical drought analysis in a Brazilian savanna basin. For this purpose, precipitation data from the twentieth-century atmospheric model ensemble (ERA-20CM) and the land component of the fifth generation of European ReAnalysis (ERA5-Land) with bias correction were used. The weather variables were obtained from the Climatic Research Unit (CRU) and the hydrological modeling was performed using the Soil and Water Assessment Tool (SWAT). The Standardized Streamflow Index (SSI) was used to calculate hydrological drought in the basin. Overall, ERA5-Land performed satisfactorily in precipitation estimation, mainly on the monthly time scale, hydrological modeling, and drought prediction. Since ERA-20CM showed unsatisfactory values for the performance statistics in all analyses, the hydrologic drought (1950 to 2018) was performed with ERA5-Land. The results showed both an increase in the number of dry months and a decrease in wet months in recent decades.
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Kaushik, S., Ravanel, L., Magnin, F., Yan, Y., Trouve, E., & Cusicanqui, D. (2022). Effects Of Topographic And Meteorological Parameters On The Surface Area Loss Of Ice Aprons In The Mont Blanc Massif (European Alps). Cryosphere, 161(101), 4251–4271.
Abstract: Ice Aprons (Ias) Are Part Of The Critical Components Of The Alpine Cryosphere. As A Result Of The Changing Climate Over The Past Few Decades, Deglaciation Has Resulted In A Surface Decrease Of Ias, Which Has Not Yet Been Documented, Except For A Few Specific Examples. In This Study, We Quantify The Effects Of Climate Change On Ias Since The Mid-20Th Century In The Mont Blanc Massif (Western European Alps). We Then Evaluate The Role Of Meteorological Parameters And The Local Topography In The Behaviour Of Ias. We Precisely Mapped The Surface Areas Of 200 Ias Using High-Resolution Aerial And Satellite Photographs From 1952, 2001, 2012 And 2019. From The Latter Inventory, The Surface Area Of The Present Individual Ias Ranges From 0.001 To 0.04 Km(2). Ias Have Lost Their Surface Area Over The Past 70 Years, With An Alarming Increase Since The Early 2000S. The Total Area, From 7.93 Km(2) In 1952, Was Reduced To 5.91 Km(2) In 2001 (-25.5 %) Before Collapsing To 4.21 Km(2) In 2019 (-47 % Since 1952). We Performed A Regression Analysis Using Temperature And Precipitation Proxies To Better Understand The Effects Of Meteorological Parameters On Ia Surface Area Variations. We Found A Strong Correlation Between Both Proxies And The Relative Area Loss Of Ias, Indicating The Significant Influence Of The Changing Climate On The Evolution Of Ias. We Also Evaluated The Role Of The Local Topographic Factors In The Ia Area Loss. At A Regional Scale, Factors Like Direct Solar Radiation And Elevation Influence The Behaviour Of Ias, While Others Like Curvature, Slope And Size Of The Ias Seem To Be Rather Important On A Local Scale.
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Kenny, G., Hyde, W., Storey, M., Garde, A., Whitehouse, M., Beck, P., et al. (2022). Ar-40/Ar-39 And Zircon U-Pb Analyses Date The Hiawatha Impact Structure, Northwest Greenland, To The Late Paleocene. Meteoritics & Planetary Science, 575.
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Kenny, G. G., Hyde, W. R., Storey, M., Garde, A. A., Whitehouse, M. J., Beck, P., et al. (2022). A Late Paleocene age for Greenland's Hiawatha impact structure. Science Advances, 8(101).
Abstract: The similar to 31-km-wide Hiawatha structure, located beneath Hiawatha Glacier in northwestern Greenland, has been proposed as an impact structure that may have formed after the Pleistocene inception of the Greenland Ice Sheet. To date the structure, we conducted Ar-40/Ar-39 analyses on glaciofluvial sand and U-Pb analyses on zircon separated from glaciofluvial pebbles of impact melt rock, all sampled immediately downstream of Hiawatha Glacier. Unshocked zircon in the impact melt rocks dates to similar to 1915 million years (Ma), consistent with felsic intrusions found in local bedrock. The Ar-40/Ar-39 data indicate Late Paleocene resetting and shocked zircon dates to 57.99 +/- 0.54 Ma, which we interpret as the impact age. Consequently, the Hiawatha impact structure far predates Pleistocene glaciation and is unrelated to either the Paleocene-Eocene Thermal Maximum or flood basalt volcanism in east Greenland. However, it was contemporaneous with the Paleocene Carbon Isotope Maximum, although the impact's exact paleoenvironmental and climatic significance awaits further investigation.
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Keuschnig, C., Martins, J., Navel, A., Simonet, P., & Larose, C. (2022). Micro-Fractionation Shows Microbial Community Changes In Soil Particles Below 20 Mu M. Frontiers In Ecology And Evolution, 101.
Abstract: Introductionmicro-Scale Analysis Of Microbes In Soil Is Essential To The Overall Understanding Of Microbial Organization, Interactions, And Ecosystem Functioning. Soil Fractionation According To Its Aggregated Structure Has Been Used To Access Microbial Habitats. While Bacterial Communities Have Been Extensively Described, Little Is Known About The Fungal Communities At Scales Relevant To Microbial Interactions. Methodswe Applied A Gentle Soil Fractionation Method To Preserve Stable Aggregated Structures Within The Range Of Micro-Aggregates And Studied Fungal And Bacterial Communities As Well As Nitrogen Cycling Potentials In The Pristine Rothamsted Park Grass Soil (Bulk Soil) As Well As In Its Particle Size Fractions (Psfs; >250 Mu M, 250-63 Mu M, 63-20 Mu M, 20-2 Mu M, <2 Mu M, And Supernatant). Resultsoverall Bacterial And Fungal Community Structures Changed In Psfs Below 20 Mu M. The Relative Abundance Of Basidiomycota Decreased With Decreasing Particle Size Over The Entire Measure Range, While Ascomycota Showed An Increase And Mucoromycota Became More Prominent In Particles Below 20 Mu M. Bacterial Diversity Was Found Highest In The < 2 Mu M Fraction, But Only A Few Taxa Were Washed-Off During The Procedure And Found In Supernatant Samples. These Taxa Have Been Associated With Exopolysaccharide Production And Biofilm Formation (E.G., Pseudomonas, Massilia, Mucilaginibacter, Edaphobaculum, Duganella, Janthinobacterium, And Variovorax). The Potential For Nitrogen Reduction Was Found Elevated In Bigger Aggregates. Discussionthe Observed Changes Below 20 Mu M Particle Are In Line With Scales Where Microbes Operate And Interact, Highlighting The Potential To Focus On Little Researched Sub-Fractions Of Micro-Aggregates. The Applied Method Shows Potential For Use In Studies Focusing On The Role Of Microbial Biofilms In Soil And Might Also Be Adapted To Research Various Other Soil Microbial Functions. Technical Advances In Combination With Micro-Sampling Methods In Soil Promise Valuable Output In Soil Studies When Particles Below 20 Mu M Are Included.
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Khadka, A., Wagnon, P., Brun, F., Shrestha, D., Lejeune, Y., & Arnaud, Y. (2022). Evaluation Of Era5-Land And Harv2 Reanalysis Data At High Elevation In The Upper Dudh Koshi Basin (Everest Region, Nepal). Journal Of Applied Meteorology And Climatology, 616(8), 931–954.
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Khan, S., Choi, Y., Morlighem, M., Rignot, E., Helm, V., Humbert, A., et al. (2022). Extensive Inland Thinning And Speed-Up Of Northeast Greenland Ice Stream. Nature, 6116(79377), 727–+.
Abstract: Over The Past Two Decades, Ice Loss From The Greenland Ice Sheet (Gris) Has Increased Owing To Enhanced Surface Melting And Ice Discharge To The Ocean(1-5). Whether Continuing Increased Ice Loss Will Accelerate Further, And By How Much, Remains Contentious(6-9). A Main Contributor To Future Ice Loss Is The Northeast Greenland Ice Stream (Negis), Greenland'S Largest Basin And A Prominent Feature Of Fast-Flowing Ice That Reaches The Interior Of The Gris(10-)(12). Owing To Its Topographic Setting, This Sector Is Vulnerable To Rapid Retreat, Leading To Unstable Conditions Similar To Those In The Marine-Based Setting Of Ice Streams In Antarctica(13-20). Here We Show That Extensive Speed-Up And Thinning Triggered By Frontal Changes In 2012 Have Already Propagated More Than 200 Km Inland. We Use Unique Global Navigation Satellite System (Gnss) Observations, Combined With Surface Elevation Changes And Surface Speeds Obtained From Satellite Data, To Select The Correct Basal Conditions To Be Used In Ice Flow Numerical Models, Which We Then Use For Future Simulations. Our Model Results Indicate That This Marine-Based Sector Alone Will Contribute 13.5-15.5 Mm Sea-Level Rise By 2100 (Equivalent To The Contribution Of The Entire Ice Sheet Over The Past 50 Years) And Will Cause Precipitous Changes In The Coming Century. This Study Shows That Measurements Of Subtle Changes In The Ice Speed And Elevation Inland Help To Constrain Numerical Models Of The Future Mass Balance And Higher-End Projections Show Better Agreement With Observations.
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Kittel, C., Amory, C., Hofer, S., Agosta, C., Jourdain, N. C., Gilbert, E., et al. (2022). Clouds Drive Differences In Future Surface Melt Over The Antarctic Ice shelves. Cryosphere, 161(7), 2655–2669.
Abstract: Recent warm atmospheric conditions have damaged the ice shelves of the Antarctic Peninsula through surface melt and hydrofracturing and could potentially initiate future collapse of other Antarctic ice shelves. However, model projections with similar greenhouse gas scenarios suggest large differences in cumulative 21st-century surface melting. So far it remains unclear whether these differences are due to variations in warming rates in individual models or whether local feedback mechanisms of the surface energy budget could also play a notable role. Here we use the polar-oriented regional climate model MAR (Modele Atmospherique Regional) to study the physical mechanisms that would control future surface melt over the Antarctic ice shelves in high-emission scenarios RCP8.5 and SSP5-8.5. We show that clouds enhance future surface melt by increasing the atmospheric emissivity and longwave radiation towards the surface. Furthermore, we highlight that differences in meltwater production for the same climate warming rate depend on cloud properties and particularly cloud phase. Clouds containing a larger amount of supercooled liquid water lead to stronger melt, subsequently favouring the absorption of solar radiation due to the snowmelt-albedo feedback. As liquid-containing clouds are projected to increase the melt spread associated with a given warming rate, they could bea major source of uncertainties in projections of the future Antarctic contribution to sea level rise.
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Kochtitzky, W., Copland, L., Van Wychen, W., Hugonnet, R., Hock, R., Dowdeswell, J., et al. (2022). The Unquantified Mass Loss Of Northern Hemisphere Marine-Terminating Glaciers From 2000-2020. Nature Communications, 131(1).
Abstract: In The Northern Hemisphere, -1500 Glaciers, Accounting For 28% Of Glacierized Area Outside The Greenland Ice Sheet, Terminate In The Ocean. Glacier Mass Loss At Their Ice-Ocean Interface, Known As Frontal Ablation, Has Not Yet Been Comprehensively Quantified. Here, We Estimate Decadal Frontal Ablation From Measurements Of Ice Discharge And Terminus Position Change From 2000 To 2020. We Bias-Correct And Cross-Validate Estimates And Uncertainties Using Independent Sources. Frontal Ablation Of Marine-Terminating Glaciers Contributed An Average Of 44.47 +/- 6.23 Gt A(-1) Of Ice To The Ocean From 2000 To 2010, And 51.98 +/- 4.62 Gt A(-1) From 2010 To 2020. Ice Discharge From 2000 To 2020 Was Equivalent To 2.10 +/- 0.22 Mm Of Sea-Level Rise And Comprised Approximately 79% Of Frontal Ablation, With The Remainder From Terminus Retreat. Near-Coastal Areas Most Impacted Include Austfonna, Svalbard, And Central Severnaya Zemlya, The Russian Arctic, And A Few Alaskan Fjords.
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Koenig, A. M., Sonke, J. E., Magand, O., Andrade, M., Moreno, I., Velarde, F., et al. (2022). Evidence For Interhemispheric Mercury Exchange In The Pacific Ocean Upper Troposphere. Journal Of Geophysical Research-Atmospheres, 1271(101).
Abstract: Even though anthropogenic mercury (Hg) emissions to the atmosphere are similar to 2.5 times higher in the Northern Hemisphere (NH) than in the Southern Hemisphere (SH), atmospheric Hg concentrations in the NH are only similar to 1.5 times higher than in the SH. Global Hg models attribute this apparent discrepancy to large SH oceanic Hg emissions or to interhemispheric exchange of Hg through the atmosphere. However, no observational data set exists to serve as a benchmark to validate whether these coarse-resolution models adequately represent the complex dynamics of interhemispheric Hg exchange. During the 2015-2016 El Nino, we observed at mount Chacaltaya in the tropical Andes a similar to 50% increase in ambient Hg compared to the year before, coinciding with a shift in synoptic transport pathways. Using this event as a case study, we investigate the impact of interhemispheric exchange on atmospheric Hg in tropical South America. We use HYSPLIT to link Hg observations to long-range transport and find that the observed Hg increase relates strongly to air masses from the tropical Pacific upper troposphere (UT), a region directly impacted by interhemispheric exchange. Inclusion of the modeled seasonality of interhemispheric air mass exchange strengthens this relationship significantly. We estimate that interhemispheric exchange drives Hg seasonality in the SH tropical Pacific UT, with strongly enhanced Hg between July and October. We validate this seasonality with previously published aircraft Hg observations. Our results suggest that the transport of NH-influenced air masses to tropical South America via the Pacific UT occurs regularly but became more detectable at Chacaltaya in 2015-2016 because of a westward shift in air mass origin.
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Kone, B., Diedhiou, A., Diawara, A., Anquetin, S., Toure, N. E., Bamba, A., et al. (2022). Influence of initial soil moisture in a regional climate model study over West Africa – Part 1: Impact on the climate mean. Hydrology And Earth System Sciences, 262(3), 711–730.
Abstract: The impact of soil moisture initial conditions on the mean climate over West Africa was examined using the latest version of the regional climate model of the International Centre for Theoretical Physics (RegCM4) at a 25 km horizontal resolution. The soil moisture reanalysis of the European Centre for Medium-Range Weather Forecasts (ECMWF) reanalysis of the 20th century (ERA-20C) was used to initialize the control experiment, while its minimum and maximum values over the entire domain were used to establish the respective initial dry and wet soil moisture conditions (hereafter referred to as dry and wet experiments, respectively). For the respective control, wet and dry experiments, an ensemble of five runs from June to September was performed. In each experiment, we analyzed the two idealized simulations most sensitive to the dry and wet soil moisture initial conditions. The impact of soil moisture initial conditions on precipitation in West Africa is linear over the Central and West Sahel regions, where dry (wet) experiments lead to a rainfall decrease (increase). The strongest precipitation increase is found over the West Sahel for wet experiments, with a maximum change value of approximately 40 %, whereas the strongest precipitation decrease is found for dry experiments over the Central Sahel, with a peak change of approximately -4 %. The sensitivity of soil moisture initial conditions can persist for 3-4 months (90-120 d) depending on the region. However, the influence on precipitation is no longer than 1 month (between 15 and 30 d). The strongest temperature decrease is located over the Central and West Sahel, with a maximum change of approximately -1.5 degrees C in wet experiments, whereas the strongest temperature increase is found over the Guinea coast and Central Sahel for the dry experiments, with a maximum change of around 0.6 degrees degrees C. A significant impact of soil moisture initial conditions on the surface energy fluxes is noted: in the wet (dry) experiments, a cooling (warming) of the surface temperature is associated with a decrease (increase) in sensible heat flux, an increase (decrease) in latent heat flux and a decrease (increase) in the boundary layer depth. Part 2 of this study (Kone et al., 2022) investigates the influence of soil moisture initial conditions on climate extremes.
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Kone, B., Diedhiou, A., Diawara, A., Anquetin, S., Toure, N. E., Bamba, A., et al. (2022). Influence of initial soil moisture in a regional climate model study over West Africa – Part 2: Impact on the climate extremes. Hydrology And Earth System Sciences, 262(3), 731–754.
Abstract: The influence of soil moisture initial conditions on the climate extreme indices over West Africa was investigated using the fourth generation of the International Centre for Theoretical Physics regional climate model (non-hydrostatic) coupled with version 4.5 of the Community Land Model (RegCM4-CLM4.5) at a 25 km spatial resolution. We initialized the control experiments with the reanalysis soil moisture data from the European Centre for Medium-Range Weather Forecasts (ECMWF) reanalysis of the 20th century (ERA-20C), while we initialized the dry and wet experiments with the maximum and minimum soil moisture values over the West Africa domain, respectively. For each experiment, an ensemble of five runs was performed for 5 years (2001-2005) with soil moisture initial conditions for the runs prescribed on 1 June and the simulations being performed over 4 months (122 d) from June to September. The performance of RegCM4-CLM4.5 with respect to simulating the 10 extreme rainfall and temperature indices used in this study is presented. The results are then discussed for the two idealized simulations that are most sensitive to the dry and wet soil moisture initial conditions in order to highlight the impacts beyond the limits of soil moisture internal forcing in the model. Over the Central Sahel, dry (wet) experiments lead to a decrease (increase) in precipitation extreme indices related to the number of events, but this was not seen for indices related to the intensity of the events. Soil moisture initial conditions unequally affect the daily minimum and maximum temperatures. The strongest impact is found on the maximum temperature: wet (dry) experiments decrease (increase) the maximum temperature over the whole region. Over the Central Sahel, wet (dry) experiments lead to a decrease (increase) in the maximum values of the minimum temperature.
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Kouadio, C. A., Kouassi, K. L., Diedhiou, A., Obahoundje, S., Amoussou, E., Kamagate, B., et al. (2022). Assessing The Hydropower Potential Using Hydrological Models And Geospatial Tools in the White Bandama Watershed (Cote d'Ivoire, West Africa). Frontiers In Water, 4.
Abstract: An assessment of hydropower potential at the watershed scale was conducted at the White Bandama Watershed (WBW) in Cote d'Ivoire (West Africa). The method used involves the application of a hydrological model [Soil and Water Assessment Tool (SWAT)] coupled with a Quantum Geographic Information System (QGIS), denoted as QSWAT, to assess the water resource availability and hydropower potential of streams and determine potential hydropower sites for future hydropower development in the watershed. Geospatial data about the topography, soil types, land use/land cover, weather, and discharge were considered in hydrological and hydro-geomorphological characterization of the watershed. Streamflow and climate data-enabled model operation and simulation of the hydrology of the watershed. The model performance and robustness were confirmed with the p-factor, r-factor, coefficient of determination R-2, and Nash-Sutcliffe (NS) efficiency coefficient. The hydropower potential of streams was evaluated by considering the simulated streamflow and water head. A total of 22 future hydropower sites was identified, geolocated, and classified with an estimated total production capacity of 538.56 MW.
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Labedz, C. R., Bartholomaus, T. C., Amundson, J. M., Gimbert, F., Karplus, M. S., Tsai, V. C. C., et al. (2022). Seismic Mapping of Subglacial Hydrology Reveals Previously Undetected Pressurization Event. Journal Of Geophysical Research-Earth Surface, 1271(3).
Abstract: Understanding the dynamic response of glaciers to climate change is vital for assessing water resources and hazards, and subglacial hydrology is a key player in glacier systems. Traditional observations of subglacial hydrology are spatially and temporally limited, but recent seismic deployments on and around glaciers show the potential for comprehensive observation of glacial hydrologic systems. We present results from a high-density seismic deployment spanning the surface of Lemon Creek Glacier, Alaska. Our study coincided with a marginal lake drainage event, which served as a natural experiment for seismic detection of changes in subglacial hydrology. We observed glaciohydraulic tremor across the surface of the glacier that was generated by the subglacial hydrologic system. During the lake drainage, the relative changes in seismic tremor power and water flux are consistent with pressurization of the subglacial system of only the upper part of the glacier. This event was not accompanied by a significant increase in glacier velocity; either some threshold necessary for rapid basal motion was not attained, or, plausibly, the geometry of Lemon Creek Glacier inhibited speedup. This pressurization event would have likely gone undetected without seismic observations, demonstrating the power of cryoseismology in testing assumptions about and mapping the spatial extent of subglacial pressurization.
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Labreuche, P., Staquet, C., & Le Sommer, J. (2022). Resonant Growth Of Inertial Oscillations From Lee Waves In The Deep Ocean. Geophysical And Astrophysical Fluid Dynamics, 1161(5-6), 351–373.
Abstract: The Interactions Between Inertial Oscillations (Io) And Lee Waves (Lw) Close To The Bottom Of The Ocean And The Role Of Io In Energy Dissipation Are Addressed For A Range Of Physical Parameters Typical Of Southern Ocean Conditions. Idealized Numerical Simulations In A Vertical Plane And Resonant Interaction Theory Are Combined For This Purpose. The Lee Waves Are Emitted By A Uniform Geostrophic Flow Over A Sinusoidal Topography For A Constant Buoyancy Frequency At Mid-Latitude. We Show That Io Can Grow By Triadic Resonant Interactions With The Lw. Two Triads Are Dominant, Which Involve Waves With Frequency Omega(Lw), F And Omega(Lw)-F, Where Omega(Lw) Is The Intrinsic Frequency Of The Lw And F The Coriolis Frequency (Assumed Positive). These Triads Differ By The Sign And Value Of The Io Vertical Wavenumber. Results From The Numerical Simulations Show That The Triad Associated With The Upward Phase Propagation Of The Io Is Selected, Consistent With Oceanic Observations, That A Good Agreement Is Obtained With The Io Growth Rate Predicted Theoretically And That The Io Develop In A Bottom Layer Of Height Less Than 1000 M. A Quasi-Steady Flow Regime Is Eventually Reached, With The Io Amplitude Being Of The Same Order As The Geostrophic Flow Speed. During This Regime, Depending Upon The Flow Parameters, The Io Kinetic Energy Is Equal To 30-70% Of The Lw Energy Flux During One Inertial Period. This Large Range Of Values Is Not Reflected In The Turbulent Kinetic Energy (Tke) Dissipation Rate, Which Is Comprised Between 10 And 30% Of The Lw Energy Flux, Whatever The Io Amplitude, Even If Vanishingly Small. Therefore, For The Set Of Parameters We Consider, The Tke Dissipation Rate Cannot Be Inferred From The Io Amplitude. Yet, The Nonlinear Interactions Between The Lee Waves And The Io Are Critical In Setting The Energy Spectrum, And Similarly For The Internal Tide And The Io At Low Latitudes According To The Literature. This Implies That Io Should Be Taken Into Account In The Parameterisation Of Mixing In The Ocean.
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Lambin, C., Fettweis, X., Kittel, C., Fonder, M., & Ernst, D. (2022). Assessment Of Future Wind Speed And Wind Power Changes Over South Greenland Using The Modele Atmospherique Regional Regional Climate Model. International Journal Of Climatology, .
Abstract: Wind Is An Infinitely Renewable Energy Source That Is Not Evenly Distributed In Space And Time. The Interconnection Of Energy-Demanding And Energyresourceful (Yet Remote) Regions Would Help Prevent Energy Scarcity In A World Where Fossil Fuels Are No Longer Used. Previous Studies Have Shown That South Greenland And West Europe Have Complementary Wind Regimes. In Particular, The Southern Tip Of Greenland, Cape Farewell, Has Gained Growing Interest For Wind Farm Development As It Is One Of The Windiest Places On Earth. In Order To Gain New Insights About Future Wind Speed Variations Over South Greenland, The Modele Atmospherique Regional (Mar), Validated Against In Situ Observations Over The Tundra Where Wind Turbines Are Most Likely To Be Installed, Is Used To Build Climate Projections Under The Emission Scenario Ssp5-8.5 By Downscaling An Ensemble Of Cmip6 Earth System Models (Esms). It Appeared That Between 1981 And 2100, The Wind Speed Is Projected To Decrease By Similar To-0.8 M.S(-1) At 100 M A.G.L. Over The Tundra Surrounding Cape Farewell. This Decrease Is Particularly Marked In Winter While In Summer, A Wind Speed Acceleration Is Projected Along The Ice Sheet Margins. An Analysis Of Twodimensional Wind Speed Changes At Different Vertical Levels Indicates That The Winter Decrease Is Likely Due To A Large-Scale Circulation Change While In Summer, The Katabatic Winds Flowing Down The Ice Sheet Are Expected To Increase Due To An Enhanced Temperature Contrast Between The Ice Sheet And The Surroundings. As For The Mean Annual Maximum Wind Power A Turbine Can Yield, A Decrease Of Similar To-178.1 W Is Projected At 100 M A.G.L. Again, The Decrease Is Especially Pronounced In Winter. Considering The Very High Winter Wind Speeds Occurring In South Greenland Which Can Cut Off Wind Turbines If Too Intense, The Projected Wind Speed Decrease Might Be Beneficial For The Establishment Of Wind Farms Near Cape Farewell.
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Lanzafame, G. M., Bessagnet, B., Srivastava, D., Jaffrezo, J. L., Favez, O., Albinet, A., et al. (2022). Modelling Aerosol Molecular Markers In A 3D Air Quality Model: Focus On anthropogenic organic markers. Science Of The Total Environment, 8358.
Abstract: aerosol markers including one primary anthropogenic marker (levoglucosan) and 4 secondary anthropogenic markers (nitrophenols, nitroguaiacols, methylnitrocatechols and phthalic acid). Modelled concentrations have been compared to measurements performed at 12 locations in France for levoglucosan in winter 2014-15, and at a sub-urban station in the Paris region over the whole year 2015 for secondary molecular markers. While a good estimation of levoglucosan concentrations by the model has been obtained for a few sites, a strong underestimation was simulated for most of the stations especially for western locations due to a probable underestimation of residential wood burning emissions. The simulated ratio between wood burning organic matter and particulate phase levoglucosan is constant only at high OM values (>10 μg m-3) indicating that using marker contribution ratio may be valid only under certain conditions. Concentrations of secondary markers were well reproduced by the model for nitrophenols and nitroguaiacols but were underestimated for methylnitrocatechols and phthalic acid highlighting missing formation pathways and/or precursor emissions. By comparing modelled to measured Gas/Particle Partitioning (GPP) of markers, the simulated partitioning of Semi-Volatile Organic Compounds (SVOCs) was evaluated. Except for nitroguaiacols and nitrophenols when ideality was assumed, the GPP for all the markers was underestimated and mainly driven by the hydrophilic partitioning. SVOCs GPP, and more generally of all SVOC contributing to the formation of SOA, could therefore be significantly
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Larbi, I., Nyamekye, C., Dotse, S. Q., Danso, D. K., Annor, T., Bessah, E., et al. (2022). Rainfall And Temperature Projections And The Implications On Streamflow and evapotranspiration in the near future at the Tano River Basin of Ghana. Scientific African, 151.
Abstract: Climate change is projected to negatively affect water security which is already a challenge in many areas of Ghana including the Tano river basin (TRB). This study assessed the projections of rainfall and temperature and its impact on streamflow and actual evapotranspiration (ET) in the TRB of Ghana for 2021-2050 relative to the period 1986-2015. The impact assessment focused on how climate change under Representative Concentration Pathways (RCP 4.5 and RCP8.5) based on an ensemble mean of two regional climate models (RCMs) would affect streamflow and ET using the Soil and Water Assessment Tool (SWAT) model. Trend analysis and quantification for the streamflow and ET were analyzed using the Mann-Kendall's and Sen's slope estimators. The results show that the mean annual rainfall of 1401.9 mm would increase slightly by 0.5 % with a decreasing trend (1.22mm/yr) under the RCP4.5 scenario, but would decrease by 3.2% with a decreasing trend (0.3m mm/yr) under the RCP8.5 scenario. The mean annual temperature showed an increase (2.1 degrees C and 2.6 degrees C) with a statistically significant increasing trend of 0.07 and 0.09 degrees C/yr under RCP 4.5 and RCP8.5 respectively. An increase in ET with a non-significant increasing trend at a rate of 0.74 and 1.07 mm/year under RCP4.5 and RCP8.5 scenarios respectively is also projected. The mean annual streamflow is projected to decrease, with the decrease been more pronounced under the RCP8.5 (37.5%) scenario compared to the RCP4.5 scenario (19.9%). In general, the outcome of this study presents a useful perspective on the vulnerability of water resources to climate change and the need for better planning and management of the water resources in the basin. (C) 2021 The Author(s). Published by Elsevier B.V. on behalf of African Institute of Mathematical Sciences / Next Einstein Initiative.
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Le Roux, E., Evin, G., Eckert, N., Blanchet, J., & Morin, S. (2022). A Non-Stationary Extreme-Value Approach For Climate Projection ensembles: application to snow loads in the French Alps. Earth System Dynamics, 131(3), 1059–1075.
Abstract: Anticipating risks related to climate extremes often relies on the quantification of large return levels (values exceeded with small probability) from climate projection ensembles. Current approaches based on multi-model ensembles (MMES) usually estimate return levels separately for each climate simulation of the MME. In contrast, using MME obtained with different combinations of general circulation model (GCM) and regional climate model (RCM), our approach estimates return levels together from the past observations and all GCM-RCM pairs, considering both historical and future periods. The proposed methodology seeks to provide estimates of projected return levels accounting for the variability of individual GCM-RCM trajectories, with a robust quantification of uncertainties. To this aim, we introduce a flexible non-stationary generalized extreme value (GEV) distribution that includes (i) piecewise linear functions to model the changes in the three GEV parameters and (ii) adjustment coefficients for the location and scale parameters to adjust the GEV distributions of the GCM-RCM pairs with respect to the GEV distribution of the past observations. Our application focuses on snow load at 1500 m elevation for the 23 massifs of the French Alps. Annual maxima are available for 20 adjusted GCM-RCM pairs from the EURO-CORDEX experiment under the scenario Representative Concentration Pathway (RCP) 8.5. Our results show with a model-as-truth experiment that at least two linear pieces should be considered for the piecewise linear functions. We also show, with a split-sample experiment, that eight massifs should consider adjustment coefficients. These two experiments help us select the GEV parameterizations for each massif. Finally, using these selected parameterizations, we find that the 50-year return level of snow load is projected to decrease in all massifs by -2.9 kN m(-2) (-50 %) on average between 1986-2005 and 2080-2099 at 1500 m elevation and RCP8.5. This paper extends the recent idea to constrain climate projection ensembles using past observations to climate extremes.
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Legchenko, A., Baltassat, J., Abbas, M., Isch, A., Amraoui, N., Azaroual, M., et al. (2022). Monitoring Unsaturated Water Flow Using Magnetic Resonance Soundings. Journal Of Hydrology, 6126.
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Legrand, M., McConnell, J. R., Preunkert, S., Bergametti, G., Chellman, N. J., Desboeufs, K., et al. (2022). Thallium Pollution In Europe Over The Twentieth Century Recorded In Alpine Ice: Contributions From Coal Burning and Cement Production. Geophysical Research Letters, 494(131).
Abstract: Emission inventories indicate that thallium, a highly toxic metal, is emitted during coal burning and cement production. These estimates have been established only for the 1980s and 1990s but up to now they have not been compared to long-term observations. Here we used alpine ice cores to document thallium pollution over Europe since similar to 1850. Ice-core thallium concentrations increased from 1890 to 1910, and decreased after 1965 to concentrations that were half 1890 levels. Comparison of ice-core trends, estimated past emissions, and state-of-the-art atmospheric aerosol transport modeling suggest that coal burning was responsible for thallium pollution in Europe, particularly from 1920 to 1965 because of high coal consumption at that time. The subsequent decline resulted from decreased coal consumption and reduced emissions following technological improvements. The ice-core data suggest that the rapid growth of cement production that took place in Europe after 1950 had a limited impact on thallium pollution.
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Lehmann, B., Anderson, R. S., Bodin, X., Cusicanqui, D., Valla, P. G., & Carcaillet, J. (2022). Alpine Rock Glacier Activity Over Holocene To Modern Timescales (Western French Alps). Earth Surface Dynamics, 101(3), 605–633.
Abstract: Active rock glaciers are some of the most frequent cryospheric landforms in midlatitude high-elevation mountain ranges. Their activity strongly influences the hydrology and geomorphology of alpine environments over short (years to decades) and long (centuries to millennia) timescales. Being conspicuous expressions of mountain permafrost and important water reserves in the form of ground ice, rock glaciers are seen as increasingly important actors in the geomorphological and hydrological evolution of mountain systems, especially in the context of current climate change. Over geological timescales, rock glaciers both reflect paleoclimate conditions and transport rock boulders produced by headwall erosion, and they therefore participate in shaping high mountain slopes. However, the dynamics of rock glaciers and their evolution over different timescales remain under-constrained. In this study, we adopt a multi-method approach, including field observations, remote sensing, and geochronology, to investigate the rock glacier system of the Vallon de la Route (Combeynot Massif, western French Alps). Remotely sensed images and correlation techniques are used to document the displacement field of the rock glacier over timescales ranging from days to decades. Additionally, to estimate displacement over periods from centuries to millennia, we employ terrestrial cosmogenic nuclide (quartz Be-10) surface-exposure dating on rock boulder surfaces located along the central flow line of the rock glacier, targeting different longitudinal positions from the headwall to the rock glacier terminus. The remote sensing analysis demonstrates that between 1960 and 2018 the two lower units of the rock glacier were motionless, the transitional unit presented an integrated surface velocity of 0.03 +/- 0.02 m a(-1), and the two upper active units above 2600 m a.s.l. showed a velocity between 0.14 +/- 0.08 and 0.15 +/- 0.05 m a(-1). Our results show Be-10 surface-exposure ages ranging from 13.10 +/- 0.51 to 1.88 +/- 0.14 ka. The spatial distribution of dated rock glacier boulders reveals a first-order inverse correlation between Be-10 surface-exposure age and elevation and a positive correlation with horizontal distance to the headwall. These observations support the hypothesis of rock boulders falling from the headwall and remaining on the glacier surface as they are transported down valley, and they may therefore be used to estimate rock glacier surface velocity over geological timescales. Our results also suggest that the rock glacier is characterized by two major phases of activity. The first phase, starting around 12 ka, displays a Be-10 age gradient with a rock glacier surface velocity of about 0.45 m a(-1), following a quiescent period between ca. 6.2 and 3.4 ka before the emplacement of the present-day upper two active units. Climatic conditions have favored an integrated rock glacier motion of around 0.18 m a(-1) between 3.4 ka and present day. These results allow us to quantify back-wearing rates of the headwall of between 1.0 and 2.5 mm a(-1), higher than catchment-integrated denudation rates estimated over millennial timescales. This suggests that the rock glacier system promotes the maintenance of high rock wall erosion by acting as debris conveyor and allowing freshly exposed bedrock surfaces to be affected by erosion processes.
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Leroux, S., Brankart, J., Albert, A., Brodeau, L., Molines, J., Jamet, Q., et al. (2022). Ensemble Quantification Of Short-Term Predictability Of The Ocean Dynamics At A Kilometric-Scale Resolution: A Western Mediterranean Test Case. Ocean Science, 181(6), 1619–1644.
Abstract: We Investigate The Predictability Properties Of The Ocean Dynamics Using An Ensemble Of Short-Term Numerical Regional Ocean Simulations Forced By Prescribed Atmospheric Conditions. In That Purpose, We Developed A Kilometric-Scale, Regional Model For The Western Mediterranean Sea (Med-West60, At 1/60 Degrees Horizontal Resolution). A Probabilistic Approach Is Then Followed, Where A Stochastic Parameterization Of Model Uncertainties Is Introduced In This Setup To Initialize Ensemble Predictability Experiments. A Set Of Three Ensemble Experiments (20 Members And 2 Months) Are Performed, One With The Deterministic Model Initiated With Perturbed Initial Conditions And Two With The Stochastic Model, For Two Different Amplitudes Of Stochastic Model Perturbations. In All Three Experiments, The Spread Of The Ensemble Is Shown To Emerge From The Smallest Scales (Kilometric Scale) And Progressively Upscales To The Largest Structures. After 2 Months, The Ensemble Variance Saturates Over Most Of The Spectrum, And The Small Scales (< 100 Km) Have Become Fully Decorrelated Across The Ensemble Members. These Ensemble Simulations Can Provide A Statistical Description Of The Dependence Between Initial Accuracy And Forecast Accuracy For Time Lags Between 1 And 20 D. The Predictability Properties Are Assessed Using A Cross-Validation Algorithm (I.E., Using Alternatively Each Ensemble Member As The Reference Truth And The Remaining 19 Members As The Ensemble Forecast) Together With A Given Statistical Score To Characterize The Initial And Forecast Accuracy. From The Joint Distribution Of Initial And Final Scores, It Is Then Possible To Quantify The Probability Distribution Of The Forecast Score Given The Initial Score Or Reciprocally To Derive Conditions On The Initial Accuracy To Obtain A Target Forecast Accuracy. The Misfit Between Ensemble Members Is Quantified In Terms Of Overall Accuracy (Crps Score), Geographical Position Of The Ocean Structures (Location Score) And Spatial Spectral Decorrelation Of The Sea Surface Height 2-D Fields (Decorrelation Score). With This Approach, We Estimate For Example That, In The Region And Period Of Interest, The Initial Location Accuracy Required (Necessary Condition) With A Perfect Model (No Model Uncertainty) To Obtain A Location Accuracy Of The Forecast Of 10 Km With A 95 % Confidence Is About 8 Km For A 1 D Forecast, 4 Km Fora 5 D Forecast And 1.5 Km Fora 10 D Forecast, And This Requirement Cannot Be Met With A 15 D Or Longer Forecast.
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Light, C. X., Arbic, B. K., Martin, P. E., Brodeau, L., Farrar, J. T., Griffies, S. M., et al. (2022). Effects of grid spacing on high-frequency precipitation variance in coupled high-resolution global ocean-atmosphere models. Climate Dynamics, .
Abstract: High-frequency precipitation variance is calculated in 12 different free-running (non-data-assimilative) coupled high resolution atmosphere-ocean model simulations, an assimilative coupled atmosphere-ocean weather forecast model, and an assimilative reanalysis. The results are compared with results from satellite estimates of precipitation and rain gauge observations. An analysis of irregular sub-daily fluctuations, which was applied by Covey et al. (Geophys Res Lett 45:12514-12522, 2018. http://doi.org/10.1029/2018GL078926) to satellite products and low-resolution climate models, is applied here to rain gauges and higher-resolution models. In contrast to lower-resolution climate simulations, which Covey et al. (2018) found to be lacking with respect to variance in irregular sub-daily fluctuations, the highest-resolution simulations examined here display an irregular sub-daily fluctuation variance that lies closer to that found in satellite products. Most of the simulations used here cannot be analyzed via the Covey et al. (2018) technique, because they do not output precipitation at sub-daily intervals. Thus the remainder of the paper focuses on frequency power spectral density of precipitation and on cumulative distribution functions over time scales (2-100 days) that are still relatively “high-frequency” in the context of climate modeling. Refined atmospheric or oceanic model grid spacing is generally found to increase high-frequency precipitation variance in simulations, approaching the values derived from observations. Mesoscale-eddy-rich ocean simulations significantly increase precipitation variance only when the atmosphere grid spacing is sufficiently fine (<0.5 degrees). Despite the improvements noted above, all of the simulations examined here suffer from the “drizzle effect”, in which precipitation is not temporally intermittent to the extent found in observations.
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Lim, S., Hwang, J., Lee, M., Czimczik, C. I., Xu, X. M., & Savarino, J. (2022). Robust Evidence Of C-14, C-13, And N-15 Analyses Indicating Fossil Fuel Sources for Total Carbon and Ammonium in Fine Aerosols in Seoul Megacity. Environmental Science & Technology, 565(111), 6894–6904.
Abstract: Carbon- and nitrogen-containing aerosols are ubiquitous in urban atmospheres and play important roles in air quality and climate change. We determined the C-14 fraction modern (f(M)) and delta C-13 of total carbon (TC) and delta N-15 of NH4+ in the PM2.5 collected in Seoul megacity during April 2018 to December 2019. The seasonal mean delta C-13 values were similar to -25.1% +/- 2.0% in warm and -24.2%+/- 0.82% in cold seasons. Mean delta N-15 values were higher in warm (16.4%+/- 2.8%) than in cold seasons (4.0%+/- 6.1%), highlighting the temperature effects on atmospheric NH3 levels and phase- equilibrium isotopic exchange during the conversion of NH3 to NH4+. While 37% +/- 10% of TC was apportioned to fossilfuel sources on the basis of f(M) values, delta N-15 indicated a higher contribution of emissions from vehicle exhausts and electricity generating units (power-plant NH3 slip) to NH3: 60% +/- 26% in warm season and 66% +/- 22% in cold season, based on a Bayesian isotope-mixing model. The collective evidence of multiple isotope analysis reasonably supports the major contribution of fossil-fuel-combustion sources to NH4+, in conjunction with TC, and an increased contribution from vehicle emissions during the severe PM2.5 pollution episodes. These findings demonstrate the efficacy of a multiple-isotope approach in providing better insight into the major sources of PM2.5 in the urban atmosphere.
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Lim, S., Lee, M., Savarino, J., & Laj, P. (2022). Oxidation Pathways And Emission Sources Of Atmospheric Particulate nitrate in Seoul: based on delta N-15 and Delta O-17 measurements. Atmospheric Chemistry And Physics, 222(8), 5099–5115.
Abstract: PM2.5 haze pollution driven by secondary inorganic NO3- has been a great concern in East Asia. It is, therefore, imperative to identify its sources and oxidation processes, for which nitrogen and oxygen stable isotopes are powerful tracers. Here, we determined the delta N-15 (NO3-) and Delta O-17 (NO3-) of PM2.5 in Seoul during the summer of 2018 and the winter of 2018-2019 and estimated quantitatively the relative contribution of oxidation pathways for particulate NO3- and investigated major NOx emission sources. In the range of PM2.5 mass concentration from 7.5 μg m(-3) (summer) to 139.0 μg m(-3) (winter), the mean delta N-15 was -0.7 parts per thousand +/- 3.3 parts per thousand and 3.8 parts per thousand +/- 3.7 parts per thousand, and the mean Delta O-17 was 23.2 parts per thousand +/- 2.2 parts per thousand and 27.7 parts per thousand +/- 2.2 parts per thousand in the summer and winter, respectively. While OH oxidation was the dominant pathway for NO3- during the summer (87 %), nighttime formation via N2O5 and NO3 was relatively more important (38 %) during the winter, when aerosol liquid water content (ALWC) and nitrogen oxidation ratio (NOR) were higher. Interestingly, the highest Delta O-17 was coupled with the lowest delta N-15 and highest NOR during the record-breaking winter PM2.5 episodes, revealing the critical role of photochemical oxidation process in severe winter haze development. For NOx sources, atmospheric delta N-15 (NOx) estimated from measured delta N-15 (NO3-) considering isotope fractionation effects indicates vehicle emissions as the most important emission source of NOx in Seoul. The contribution from biogenic soil and coal combustion was slightly increased in summer and winter, respectively. Our results built on a multiple-isotope approach provide the first explicit evidence for NO3- formation processes and major NOx emission sources in the Seoul megacity and suggest an effective mitigation measure to improve PM2.5 pollution.
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Llovel, W., Kolodziejczyk, N., Close, S., Penduff, T., Molines, J. M., & Terray, L. (2022). Imprint of intrinsic ocean variability on decadal trends of regional sea level and ocean heat content using synthetic profiles. Environmental Research Letters, 171(4).
Abstract: The global ocean is warming and has absorbed 90% of the Earth Energy Imbalance over 2010-2018 leading to global mean sea level rise. Both ocean heat content (OHC) and sea level trends show large regional deviations from their global means. Both quantities have been estimated from in-situ observations for years. However, in-situ profile coverage is spatially uneven, leading to uncertainties when assessing both OHC and sea level trends, especially at regional scale. Recently, a new possible driver of regional sea level and OHC trends has been highlighted using eddy-permitting ensemble ocean simulations over multiple decades: non-linear ocean processes produce chaotic fluctuations, which yield random contributions to regional decadal OHC and sea level trends. In-situ measurements capture a combination of the atmospherically-forced response and this intrinsic ocean variability. It is therefore important to understand the imprint of the chaotic ocean variability recorded by the in-situ measurement sampling in order to assess its impact and associated uncertainty on regional budgets. A possible approach to investigate this problem is to use a set of synthetic in-situ-like profiles extracted from an ensemble of forced ocean simulations started from different states and integrated with the same atmospheric forcing. Comparisons between the original ensemble outputs and the remapped, subsampled, in-situ-like profiles elucidate the contribution of chaotic ocean variability to OHC and regional sea level trends. Our results show that intrinsic variability may be large in eddy-active regions in the gridded model outputs, and remains substantial when using the in-situ sampling-based estimates. Using the latter, the same result is also found on large scales, for which atmospheric forcing has been identified as the main driver. Our results suggest accounting for this intrinsic ocean variability when assessing regional OHC and sea level trend budgets on decadal time scales.
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Maclennan, M., Lenaerts, J., Shields, C., & Wille, J. (2022). Contribution Of Atmospheric Rivers To Antarctic Precipitation. Geophysical Research Letters, 494(181).
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Maier, N., Gimbert, F., & Gillet-Chaulet, F. (2022). Threshold Response To Melt Drives Large-Scale Bed Weakening In Greenland. Nature, 6076(79207), 714–+.
Abstract: Ice speeds in Greenland are largely set by basal motion(1), which is modulated by meltwater delivery to the ice base(2-4). Evidence suggests that increasing melt rates enhance the subglacial drainage network's capacity to evacuate basal water, increasing bed friction and causing the ice to slow(5-10). This limits the potential of melt forcing to increase mass loss as temperatures increase(11). Here we show that melt forcing has a pronounced influence on dynamics, but factors besides melt rates primarily control its impact. Using a method to examine friction variability across the entirety of western Greenland, we show that the main impact of melt forcing is an abrupt north-to-south change in bed strength that cannot be explained by changes in melt production. The southern ablation zone is weakened by 20-40 per cent compared with regions with no melt, whereas in northern Greenland the ablation zone is strengthened. We show that the weakening is consistent with persistent basal water storage and that the threshold is linked to differences in sliding and hydropotential gradients, which exert primary control on the pressures within drainage pathways that dewater the bed. These characteristics are mainly set by whether a margin is land or marine terminating, suggesting that dynamic changes that increase mass loss are likely to occur in northern Greenland as temperatures increase. Our results point to physical representations of these findings that will improve simulated ice-sheet evolution at centennial scales.
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Mandal, A., Angchuk, T., Azam, M., Ramanathan, A., Wagnon, P., Soheb, M., et al. (2022). An 11-Year Record Of Wintertime Snow-Surface Energy Balance And Sublimation At 4863 M A.S.L. On The Chhota Shigri Glacier Moraine (Western Himalaya, India). Cryosphere, 161(9), 3775–3799.
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Mannerfelt, E., Dehecq, A., Hugonnet, R., Hodel, E., Huss, M., Bauder, A., et al. (2022). Halving Of Swiss Glacier Volume Since 1931 Observed From Terrestrial Image Photogrammetry. Cryosphere, 161(8), 3249–3268.
Abstract: The Monitoring Of Glaciers In Switzerland Has A Long Tradition, Yet Glacier Changes During The 20Th Century Are Only Known Through Sparse Observations. Here, We Estimate A Halving Of Swiss Glacier Volumes Between 1931 And 2016 By Mapping Historical Glacier Elevation Changes At High Resolution. Our Analysis Relies On A Terrestrial Image Archive Known As Terra, Which Covers About 86 % Of The Swiss Glacierised Area With 21 703 Images Acquired During The Period 1916-1947 (With A Median Date Of 1931). We Developed A Semi-Automated Workflow To Generate Digital Elevation Models (Dems) From These Images, Resulting In A 45 % Total Glacier Coverage. Using The Geodetic Method, We Estimate A Swisswide Glacier Mass Balance Of -0.52 +/- 0.09 M W.E. A(-1) Between 1931 And 2016. This Equates To A 51.5 +/- 8.0 % Loss In Glacier Volume. We Find That Low-Elevation, High-Debriscover, And Gently Sloping Glacier Termini Are Conducive To Particularly High Mass Losses. In Addition To These Glacier-Specific, Quasi-Centennial Elevation Changes, We Present A New Inventory Of Glacier Outlines With Known Timestamps And Complete Attributes From Around 1931. The Fragmented Spatial Coverage And Temporal Heterogeneity Of The Terra Archive Are The Largest Sources Of Uncertainty In Our Glacier-Specific Estimates, Reaching Up To 0.50 M W.E. A(-1). We Suggest That The High-Resolution Mapping Of Historical Surface Elevations Could Also Unlock Great Potential For Research Fields Other Than Glaciology.
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Marengo, J. A., Jimenez, J. C., Espinoza, J. C., Cunha, A. P., & Aragao, L. E. O. (2022). Increased climate pressure on the agricultural frontier in the Eastern Amazonia-Cerrado transition zone. Scientific Reports, 121(1).
Abstract: Several large-scale drivers of both anthropogenic and natural environmental changes are interacting nonlinearly in the transition zone between eastern Amazonia and the adjacent Cerrado, considered to be another Brazilian agricultural frontier. Land-use change for agrobusiness expansion together with climate change in the transition zone between eastern Amazonia and the adjacent Cerrado may have induced a worsening of severe drought conditions over the last decade. Here we show that the largest warming and drying trends over tropical South America during the last four decades are observed to be precisely in the eastern Amazonia-Cerrado transition region, where they induce delayed wet-season and worsen severe drought conditions over the last decade. Our results evidence an increase in temperature, vapor pressure deficit, subsidence, dry-day frequency, and a decrease in precipitation, humidity, and evaporation, plus a delay in the onset of the wet season, inducing a higher risk of fire during the dry-to-wet transition season. These findings provide observational evidence of the increasing climatic pressure in this area, which is sensitive for global food security, and the need to reconcile agricultural expansion and protection of natural tropical biomes.
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Masalaite, A., Bycenkien, S., Pauraite, J., Garbariene, I., Bozzetti, C., Besombes, J. L., et al. (2022). Seasonal Observation And Source Apportionment Of Carbonaceous Aerosol from forested rural site (Lithuania). Atmospheric Environment, 2722.
Abstract: In this work, we conducted a study of the stable carbon isotope ratios of total carbon (delta C-13(TC)) for submicron aerosol particles (< 1 μm) that were collected year round (2014) at a hemiboreal forest site in Lithuania. Higher delta C-13(TC) values characterised the seasonal variation in delta C-13(TC) during the cold season (average-26.9 +/- 0.7%o) with lower values observed during the warm season (-27.6 +/- 0.6%o). The total carbon (TC) concentration was below 8 μg/m3 during the one-year measurement period. There was one pollution event in autumn when concentrations reached up to 14.8 μg/m(3). In addition to the offline analysis of the filter samples, the online measurements of aerosol physical and chemical properties were conducted from 15 May to September 27, 2014 by operating the Aethalometer AE-31 and a quadrupole-type Aerosol Chemical Speciation Monitor (ACSM). Source apportionment was conducted by analysing the ACSM mass spectra using Positive Matrix Factorisation (PMF). Three main factors were derived, pointing to primary emissions from biomass burning along with the secondary formation of less and more oxygenated organic aerosol of biogenic origin. A comparative analysis of delta C-13(TC) with organic carbon (OC), elemental carbon (EC), and organic markers justified two dominant sources (biomass burning and fossil fuel combustion) of aerosol particles at the hemiboreal forest site during the cold season.
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Mateo, E. I., Mark, B. G., Hellstrom, R. A., Baraer, M., McKenzie, J. M., Condom, T., et al. (2022). High-Temporal-Resolution Hydrometeorological Data Collected In The tropical Cordillera Blanca, Peru (2004-2020). Earth System Science Data, 141(6), 2865–2882.
Abstract: This article presents a comprehensive hydrometeorological dataset collected over the past two decades throughout the Cordillera Blanca, Peru. The data-recording sites, located in the upper portion of the Rio Santa valley, also known as the Callejon de Huaylas, span an elevation range of 3738-4750ma.s.l. As many historical hydrological stations measuring daily discharge across the region became defunct after their installation in the 1950s, there was a need for new stations to be installed and an opportunity to increase the temporal resolution of the streamflow observations. Through inter-institutional collaboration, the hydrometeorological network described in this paper was deployed with the goal of evaluating how progressive glacier mass loss was impacting stream hydrology, and understanding better the local manifestation of climate change over diurnal to seasonal and interannual time scales. The four automatic weather stations supply detailed meteorological observations and are situated in a variety of mountain landscapes, with one on a high-mountain pass, another next to a glacial lake, and two in glacially carved valleys. Four additional temperature and relative humidity loggers complement the weather stations within the Llanganuco valley by providing these data across an elevation gradient. The six streamflow gauges are located in tributaries to the Rio Santa and collect high-temporal-resolution runoff data. The datasets presented here are available freely from https://doi.org/10.4211/hs.35a670e6c5824ff89b3b74fe45ca90e0 (Mateo et al., 2021). Combined, the hydrological and meteorological data collected throughout the Cordillera Blanca enable detailed research of atmospheric and hydrological processes in tropical high-mountain terrain.
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Milillo, P., Rignot, E., Rizzoli, P., Scheuchl, B., Mouginot, J., Bueso-Bello, J. L., et al. (2022). Rapid glacier retreat rates observed in West Antarctica. Nature Geoscience, 151(1), 48–+.
Abstract: The Pope, Smith and Kohler glaciers, in the Amundsen Sea Embayment of West Antarctica, have experienced enhanced ocean-induced ice-shelf melt, glacier acceleration, ice thinning and grounding-line retreat in the past 30 years. Here we present observations of the grounding-line retreat of these glaciers since 2014 using a constellation of interferometric radar satellites combined with precision surface elevation data. We find that the grounding lines develop spatially variable, kilometre-scale, tidally induced migration zones. After correction for tidal effects, we detect a sustained pattern of retreat coincident with high melt rates of ungrounded ice, marked by episodes of more rapid retreat. In 2017, Pope Glacier retreated 3.5 km in 3.6 months, or 11.7 km yr(-1). In 2016-2018, Smith West retreated at 2 km yr(-1) and Kohler at 1.3 km yr(-1). While the retreat slowed in 2018-2020, these retreat rates are faster than anticipated by numerical models on yearly timescales. We hypothesize that the rapid retreat is caused by unrepresented, vigorous ice-ocean interactions acting within newly formed cavities at the ice-ocean boundary. The Pope, Smith and Kohler glaciers in West Antarctica have exhibited faster than expected retreat rates in recent years, according to grounding-line observations from satellite radar interferometry.
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Millan, R., Mouginot, J., Rabatel, A., & Morlighem, M. (2022). Ice velocity and thickness of the world's glaciers. Nature Geoscience, 151(2), 124–+.
Abstract: The effect of climate change on water resources and sea-level rise is largely determined by the size of the ice reservoirs around the world and the ice thickness distribution, which remains uncertain. Here, we present a comprehensive high-resolution mapping of ice motion for 98% of the world's total glacier area during the period 2017-2018. We use this mapping of glacier flow to generate an estimate of global ice volume that reconciles ice thickness distribution with glacier dynamics and surface topography. The results suggest that the world's glaciers have a potential contribution to sea-level rise of 257 +/- 85 mm, which is 20% less than previously estimated. At low latitudes, our findings highlight notable changes in freshwater resources, with 37% more ice in the Himalayas and 27% less ice in the tropical Andes of South America, affecting water availability for local populations. This mapping of glacier flow and thickness redefines our understanding of global ice-volume distribution and has implications for the prediction of glacier evolution around the world, since accurate representations of glacier geometry and dynamics are of prime importance to glacier modelling. Potential sea-level rise from the world's glaciers is 20% less than previously thought, according to an estimate based on high-resolution maps of glacier ice velocity and thickness.
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Millan, R., Mouginot, J., Rabatel, A., & Morlighem, M. (2022). Ice Velocity And Thickness Of The World'S Glaciers (Vol 15, Pg 124, 2022). Nature Geoscience, .
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Moschos, V., Dzepina, K., Bhattu, D., Lamkaddam, H., Casotto, R., Daellenbach, K. R., et al. (2022). Equal abundance of summertime natural and wintertime anthropogenic Arctic organic aerosols. Nature Geoscience, .
Abstract: Organic aerosols in the Arctic are predominantly fuelled by anthropogenic sources in winter and natural sources in summer, according to observations from eight sites across the Arctic Aerosols play an important yet uncertain role in modulating the radiation balance of the sensitive Arctic atmosphere. Organic aerosol is one of the most abundant, yet least understood, fractions of the Arctic aerosol mass. Here we use data from eight observatories that represent the entire Arctic to reveal the annual cycles in anthropogenic and biogenic sources of organic aerosol. We show that during winter, the organic aerosol in the Arctic is dominated by anthropogenic emissions, mainly from Eurasia, which consist of both direct combustion emissions and long-range transported, aged pollution. In summer, the decreasing anthropogenic pollution is replaced by natural emissions. These include marine secondary, biogenic secondary and primary biological emissions, which have the potential to be important to Arctic climate by modifying the cloud condensation nuclei properties and acting as ice-nucleating particles. Their source strength or atmospheric processing is sensitive to nutrient availability, solar radiation, temperature and snow cover. Our results provide a comprehensive understanding of the current pan-Arctic organic aerosol, which can be used to support modelling efforts that aim to quantify the climate impacts of emissions in this sensitive region.
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Moschos, V., Schmale, J., Aas, W., Becagli, S., Calzolai, G., Eleftheriadis, K., et al. (2022). Elucidating the present-day chemical composition, seasonality and source regions of climate-relevant aerosols across the Arctic land surface. Environmental Research Letters, 171(3).
Abstract: The Arctic is warming two to three times faster than the global average, and the role of aerosols is not well constrained. Aerosol number concentrations can be very low in remote environments, rendering local cloud radiative properties highly sensitive to available aerosol. The composition and sources of the climate-relevant aerosols, affecting Arctic cloud formation and altering their microphysics, remain largely elusive due to a lack of harmonized concurrent multi-component, multi-site, and multi-season observations. Here, we present a dataset on the overall chemical composition and seasonal variability of the Arctic total particulate matter (with a size cut at 10 μm, PM10, or without any size cut) at eight observatories representing all Arctic sectors. Our holistic observational approach includes the Russian Arctic, a significant emission source area with less dedicated aerosol monitoring, and extends beyond the more traditionally studied summer period and black carbon/sulfate or fine-mode pollutants. The major airborne Arctic PM components in terms of dry mass are sea salt, secondary (non-sea-salt, nss) sulfate, and organic aerosol (OA), with minor contributions from elemental carbon (EC) and ammonium. We observe substantial spatiotemporal variability in component ratios, such as EC/OA, ammonium/nss-sulfate and OA/nss-sulfate, and fractional contributions to PM. When combined with component-specific back-trajectory analysis to identify marine or terrestrial origins, as well as the companion study by Moschos et al 2022 Nat. Geosci. focusing on OA, the composition analysis provides policy-guiding observational insights into sector-based differences in natural and anthropogenic Arctic aerosol sources. In this regard, we first reveal major source regions of inner-Arctic sea salt, biogenic sulfate, and natural organics, and highlight an underappreciated wintertime source of primary carbonaceous aerosols (EC and OA) in West Siberia, potentially associated with the oil and gas sector. The presented dataset can assist in reducing uncertainties in modelling pan-Arctic aerosol-climate interactions, as the major contributors to yearly aerosol mass can be constrained. These models can then be used to predict the future evolution of individual inner-Arctic atmospheric PM components in light of current and emerging pollution mitigation measures and improved region-specific emission inventories.
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Moseid, K., Schulz, M., Eichler, A., Schwikowski, M., Mcconnell, J., Olivie, D., et al. (2022). Using Ice Cores To Evaluate Cmip6 Aerosol Concentrations Over The Historical Era. Journal Of Geophysical Research-Atmospheres, 1271(181).
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Murfitt, J., Duguay, C., Picard, G., & Gunn, G. (2022). Investigating The Effect Of Lake Ice Properties On Multifrequency Backscatter Using The Snow Microwave Radiative Transfer Model. Ieee Transactions On Geoscience And Remote Sensing, 606.
Abstract: Recent Investigations Using Polarimetric Decomposition And Numerical Models Have Helped To Improve The Understanding Of How Radar Signals Interact With Lake Ice. However, Further Research Is Needed On How Radar Signals Are Impacted By Varying Lake Ice Properties. Radiative Transfer (Rt) Models Provide One Method Of Improving This Understanding. These Are The First Published Experiments Using The Snow Microwave Rt (Smrt) Model To Investigate The Response Of Different Frequencies (L-, C-, And X-Band) At Horizontal-Horizontal (Hh) And Vertical-Vertical (Vv) Polarizations Using Various Incidence Angles (20 Degrees, 30 Degrees, And 40 Degrees) To Changes In Ice Thickness, Porosity, Bubble Radius, And Ice-Water Interface Roughness. This Is Also The First Use Of Smrt In Combination With A Thermodynamic Lake Ice Model. Experiments Were For A Lake With Tubular Bubbles And One Without Tubular Bubbles Under Difference Scenarios. An Analysis Of The Backscatter Response To Different Properties Indicates That Increasing Ice Thickness And Layer Porosity Have Little Impact On Backscatter From Lake Ice. X-Band Backscatter Shows Increased Response To Surface Ice Layer Bubble Radius; However, This Was Limited To Other Frequencies Except At Shallower Incidence Angles (40 Degrees). All Three Frequencies Display The Largest Response To Increasing Root Mean Square (Rms) Height At The Ice-Water Interface, Which Supports Surface Scattering At The Ice-Water Interface As Being The Dominant Scattering Mechanism. These Results Demonstrate That The Smrt Is A Valuable Tool For Understanding The Response Of Backscatter To Changes In Freshwater Lake Ice Properties And Could Be Used In The Development Of Inversion Models.
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Nair, S., Kotnik, J., Gacnik, J., Zivkovic, I., Koenig, A., Mlakar, T., et al. (2022). Dispersion Of Airborne Mercury Species Emitted From The Cement Plant. Environmental Pollution, 3123.
Abstract: The Cement Industry Is The Second Largest Source Of Anthropogenic Mercury (Hg) Emissions In Europe, Accounting For 11% Of Global Anthropogenic Hg Emissions. The Main Objective Of This Study Was To Examine The Influence Of Hg Emissions From The Salonit Anhovo Cement Plant On Hg Levels Measured In The Ambient Air At Vodarna, 1 Km Downwind From The Flue Gas Chimney. The Findings Reveal That The Plant Raw Mill Operational Status Plays An Important Role In Hg Concentrations In The Flue Gas Emitted From The Plant. Emitted Total Gaseous Mercury Was, On Average, Higher (49.4 Mu G/M(3)) When Raw Mills Were In The Direct Mode (Both Raw Mills-Off) And Lower (23.4 Mu G/M(3)) In The Combined Mode (Both Raw Mills-On). The Average Hg Concentrations In Vodarna Were 3.14 Ng/M(3) For Gaseous Elemental Mercury, 53.7 Pg/M(3) For Gaseous Oxidised Mercury, And 41.9 Pg/M(3) For Particulate Bound Mercury For The Whole Measurement Period. Atmospheric Hg Speciation In Vodarna, Coupled With Plant Emissions And Wind Data, Has Revealed That The Total Gaseous Mercury Emitted From The Cement Plant Is Clearly Related To All Hg Species Measured In Vodarna. Wind Blowing From The Northeastern Quadrant (Mostly Ne, Ene) Is Responsible For The Elevated Hg Levels In Vodarna, Where Gaseous Oxidised Mercury Levels Are Highly Linked To The Cement Plant Emissions. However, Elevated Levels Of Hg Species In The Absence Of Northeastern Winds Indicate Potential Inputs From Other Unknown Local Sources As Well As Inputs From Regional And Global Transport Mechanisms.
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Nanni, U., Roux, P., Gimbert, F., & Lecointre, A. (2022). Dynamic Imaging Of Glacier Structures At High-Resolution Using Source Localization With a Dense Seismic Array. Geophysical Research Letters, 494(6).
Abstract: Dense seismic array monitoring combined with advanced processing can help retrieve and locate a variety of seismic sources with unprecedented resolution and spatial coverage. We present a methodology that goes beyond classical localization algorithms through gathering various types of sources (impulsive or continuous) using a single scheme based on a gradient-descent optimization and evaluating different levels of phase coherence. We apply our methodology on an Alpine glacier and demonstrate that we can retrieve the dynamics of active crevasses with a metric resolution using sources associated with high phase coherence; the presence of diffracting materials (e.g., rocks) trapped in transverse crevasses using sources with moderate phase coherence; and the two-dimensional time evolution of the subglacial hydrology system using sources with low phase coherence. Our study highlights the strength of using an appropriate and systematic seismological approach to image a wide range of subsurface structures and phenomena in settings with complex wavefields.
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Nguyen, A., Dao, T., Strady, E., Nguyen, T., Aime, J., Gratiot, N., et al. (2022). Phytoplankton characterization in a tropical tidal river impacted by a megacity: the case of the Saigon River (Southern Vietnam). Environmental Science And Pollution Research, .
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Nguyen, A. T., Nemery, J., Gratiot, N., Dao, T. S., Le, T. T. M., Baduel, C., et al. (2022). Does Eutrophication Enhance Greenhouse Gas Emissions In Urbanized tropical estuaries? Environmental Pollution, 3033.
Abstract: Estuaries are considered as important sources of the global emission of greenhouse gases (GHGs). Urbanized estuaries often experience eutrophication under strong anthropogenic activities. Eutrophication can enhance phytoplankton abundance, leading to carbon dioxide (CO2) consumption in the water column. Only a few studies have evaluated the relationship between GHGs and eutrophication in estuaries. In this study, we assessed the concentrations and fluxes of CO2, methane (CH4) and nitrous oxide (N2O) in combination with a suite of biogeochemical variables in four sampling campaigns over two years in a highly urbanized tropical estuary in Southeast Asia (the Saigon River Estuary, Vietnam). The impact of eutrophication on GHGs was evaluated through several statistical methods and interpreted by biological processes. The average concentrations of CO2, CH4 and N2O at the Saigon River in 2019-2020 were 3174 +/- 1725 μgC-CO2 L-1, 5.9 +/- 16.8 μgC-CH4 L-1 and 3.0 +/- 4.8 μgN-N2O L-1, respectively. Their concentrations were 13-18 times, 52-332 times, and 9-37 times higher than the global mean concentrations of GHGs, respectively. While CO2 concentration had no clear seasonal pattern, N2O and CH(4 )concentrations significantly differed between the dry and the rainy seasons. The increase in eutrophication status along the dense urban area was linearly correlated with the increase in GHGs concentrations. The presence of both nitrification and denitrification resulted in elevated N2O concentrations in this urban area of the estuary. The high concentration of CO2 was contributed by the high concentration of organic carbon and mineralization process. GHGs fluxes at the Saigon River Estuary were comparable to other urbanized estuaries regardless of climatic condition. Control of eutrophication in urbanized estuaries through the implantation of efficient wastewater treatment facilities will be an effective solution in mitigating the global warming potential caused by estuarine emissions.
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Nguyen, A. T., Nemery, J., Gratiot, N., Dao, T. S., Le, T. T. M., Baduel, C., et al. (2022). Does Eutrophication Enhance Greenhouse Gas Emissions In Urbanized tropical estuaries? Environmental Pollution, 3033.
Abstract: Estuaries are considered as important sources of the global emission of greenhouse gases (GHGs). Urbanized estuaries often experience eutrophication under strong anthropogenic activities. Eutrophication can enhance phytoplankton abundance, leading to carbon dioxide (CO2) consumption in the water column. Only a few studies have evaluated the relationship between GHGs and eutrophication in estuaries. In this study, we assessed the concentrations and fluxes of CO2, methane (CH4) and nitrous oxide (N2O) in combination with a suite of biogeochemical variables in four sampling campaigns over two years in a highly urbanized tropical estuary in Southeast Asia (the Saigon River Estuary, Vietnam). The impact of eutrophication on GHGs was evaluated through several statistical methods and interpreted by biological processes. The average concentrations of CO2, CH4 and N2O at the Saigon River in 2019-2020 were 3174 +/- 1725 μgC-CO2 L-1, 5.9 +/- 16.8 μgC-CH4 L-1 and 3.0 +/- 4.8 μgN-N2O L-1, respectively. Their concentrations were 13-18 times, 52-332 times, and 9-37 times higher than the global mean concentrations of GHGs, respectively. While CO2 concentration had no clear seasonal pattern, N2O and CH(4 )concentrations significantly differed between the dry and the rainy seasons. The increase in eutrophication status along the dense urban area was linearly correlated with the increase in GHGs concentrations. The presence of both nitrification and denitrification resulted in elevated N2O concentrations in this urban area of the estuary. The high concentration of CO2 was contributed by the high concentration of organic carbon and mineralization process. GHGs fluxes at the Saigon River Estuary were comparable to other urbanized estuaries regardless of climatic condition. Control of eutrophication in urbanized estuaries through the implantation of efficient wastewater treatment facilities will be an effective solution in mitigating the global warming potential caused by estuarine emissions.
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Nicolaus, M., Perovich, D. K., Spreen, G., Granskog, M. A., von Albedyll, L., Angelopoulos, M., et al. (2022). Overview of the MOSAiC expedition: Snow and sea ice. Elementa-Science Of The Anthropocene, 101(1).
Abstract: Year-round observations of the physical snow and ice properties and processes that govern the ice pack evolution and its interaction with the atmosphere and the ocean were conducted during the Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) expedition of the research vessel Polarstern in the Arctic Ocean from October 2019 to September 2020. This work was embedded into the interdisciplinary design of the 5 MOSAiC teams, studying the atmosphere, the sea ice, the ocean, the ecosystem, and biogeochemical processes. The overall aim of the snow and sea ice observations during MOSAiC was to characterize the physical properties of the snow and ice cover comprehensively in the central Arctic over an entire annual cycle. This objective was achieved by detailed observations of physical properties and of energy and mass balance of snow and ice. By studying snow and sea ice dynamics over nested spatial scales from centimeters to tens of kilometers, the variability across scales can be considered. On-ice observations of in situ and remote sensing properties of the different surface types over all seasons will help to improve numerical process and climate models and to establish and validate novel satellite remote sensing methods; the linkages to accompanying airborne measurements, satellite observations, and results of numerical models are discussed. We found large spatial variabilities of snow metamorphism and thermal regimes impacting sea ice growth. We conclude that the highly variable snow cover needs to be considered in more detail (in observations, remote sensing, and models) to better understand snow-related feedback processes. The ice pack revealed rapid transformations and motions along the drift in all seasons. The number of coupled ice-ocean interface processes observed in detail are expected to guide upcoming research with respect to the changing Arctic sea ice.
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Noe, S. M., Tabakova, K., Mahura, A., Lappalainen, H. K., Kosmale, M., Heilimo, J., et al. (2022). Arctic Observations And Sustainable Development Goals – Contributions and examples from ERA-PLANET iCUPE data. Environmental Science & Policy, 1321, 323–336.
Abstract: Integrative and Comprehensive Understanding on Polar Environments (iCUPE) project developed 24 novel datasets utilizing in-situ observational capacities within the Arctic or remote sensing observations from ground or from space. The datasets covered atmospheric, cryospheric, marine, and terrestrial domains. This paper connects the iCUPE datasets to United Nations' Sustainable Development Goals and showcases the use of selected datasets as knowledge provision services for policy- and decision-making actions. Inclusion of indigenous and societal knowledge into the data processing pipelines enables a feedback mechanism that facilitates data driven public services.
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Nsangou, D., Kpoumie, A., Mfonka, Z., Ngouh, A. N., Fossi, D. H., Jourdan, C., et al. (2022). Urban Flood Susceptibility Modelling Using Ahp And Gis Approach: Case Of the Mfoundi watershed at Yaounde in the South-Cameroon plateau. Scientific African, 151.
Abstract: Floods are considered as the natural hazards that affect the world's major metropolises the most. Thus, the present study aimed at evaluating the sensitivity to flood risks of the Mfoundi watershed (96.5 km(2)) located in the heart of the Cameroonian political capital in a tropical humid forest zone, more precisely in the South Cameroon plateau. The methodological approach adopted was to identify the factors that most favor the risk of flooding in the area from intense literature review and field investigations; the analysis of these factors and the calculation of the Flood Harzard Index (FHI) using the Analytical Hierarchy Process (AHP) approach coupled with the Geographical Information System (GIS) environment. The results reveal that among the ten parameters of the natural environment (elevation, drainage density, rainfall, slope, distance from the river, topographic humidity, hydraulic conductivity, groundwater level, geology and land cover) selected, the land cover, elevation and the geology are the factors that most influences the flooding phenomenon in the area. The value of Flood Hazard Index (FHI) varied from 4.16 to 9.16, the higher the value, the more sensitive the area is to the risk of flooding. Five main classes of flood susceptibility are highlighted: very low, low, moderate, high and very high, representing 9.50, 26, 23, 22 and 19.5%, respectively of the study area. To validate the efficiency of the obtained flood susceptibility map, the adopted Area Under the Curve (AUC) method shows a very good accuracy (0.84 or 84%). The results of this study constitute a basic tool for decision-making for environmental management by public authorities and decentralised territorial authorities with territorial jurisdiction. (C) 2021 Published by Elsevier B.V. on behalf of African Institute of Mathematical Sciences / Next Einstein Initiative.
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Obahoundje, S., & Diedhiou, A. (2022). Potential impacts of climate, land use and land cover changes on hydropower generation in West Africa: a review. Environmental Research Letters, 171(4).
Abstract: This study aims to review the existing literature on the past and future effects of climate, land use, and land cover changes on hydropower generation in West Africa (WA), based on listings in the Scopus and Google Scholar databases. This review shows that several African hydropower plants have experienced repeated power disruptions over the last three decades due to climate change and variability but it is less documented how increasing land use and land cover changes around the major dams have impacted the hydrological system and the hydropower generation. In the future, the risks of hydropower in WA may not be equally distributed within a country or region. Despite uncertainties in precipitation and on impacts on streamflow and water level in major basins, climate change is likely to reduce the available water over the range of 10%-20% (15%-40%) for the RCP4.5 (RCP8.5) scenario by 2050, which may considerably affect the water demand across all sectors, including hydropower. However, in the Kainji dam (Niger River basin), models project an increase in rainfall favorable to hydropower production for both RCP4.5 and RCP8.5. In contrast, within the Black Volta sub-basin, the intensification of land use is predicted to favor runoff and, consequently, an increase in the generation of Bui hydropower in the near future, even though models predict a rainfall decrease. This increase in land use for agriculture to feed a growing population has other adverse effects that need to be assessed, namely sedimentation and siltation, which are harmful to hydropower plants. Finally, the combined impact of climate and land use changes on the efficiency of hydroelectric infrastructure in WA is not well documented, while sustainable planning and investments in the hydropower sector require consideration of the nexus between climate, land use changes, and water.
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Obahoundje, S., Diedhiou, A., Dubus, L., Alamou, E., Amoussou, E., Akpoti, K., et al. (2022). Modeling Climate Change Impact On Inflow And Hydropower Generation Of Nangbeto Dam In West Africa Using Multi-Model Cordex Ensemble And Ensemble Machine Learning. Applied Energy, 3253.
Abstract: Climate Change (Cc) Poses A Threat To Renewable Hydropower, Which Continues To Play A Significant Role In Energy Generation In West Africa (Wa). Thus, The Assessment Of The Impacts Of Climate Change And Climate Variability On Hydropower Generation Is Critical For Dam Management. This Study Develops A Framework Based On Ensemble Climate Models And Ensemble Machine Learning Methods To Assess The Projected Impacts Of Cc On Inflow To The Reservoir And Hydropower Generation At The Nangbeto Hydropower Plant In Wa. Inflow To Reservoir And Energy Generation For The Future (2020-2099) Is Modeled Using Climate Models Output Data From Coordi-Nated Regional Downscaling Experiment To Produce A Publicly Accessible Hydropower Dataset From 1980 To 2099. The Bias-Adjusted Ensemble Mean Of Eleven Climate Models For Representative Concentration Pathways (Rc4.5 And Rcp8.5) Are Used. The Added Value Of This Approach Is To Use Fewer Input Data (Temperature And Precipi-Tation) While Focusing On Their Lagged Effect On Inflow And Energy. Generally, The Model Output Strongly Cor-Relates With The Observation (1986-2005) With A Pearson Correlation Of 0.86 For Energy And 0.82 For Inflow While The Mean Absolute Error Is 2.97% For Energy And 9.73% For Inflow. The Results Reveals That Both Inflow And Energy Simulated Over The Future Periods (2020-2039, 2040-2059, 2060-2079, And 2080-2099) Will Decrease Relative To The Historical Period (1986-2005) For Both Rcps In The Range Of (2.5-20.5% And 1-8.5% For Inflow And Energy, Respectively), At Annual, Monthly And Seasonal Time Scales. Therefore, These Results Should Be Considered By Decision-Makers When Assessing The Best Option For The Energy Mix Development Plan.
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Obahoundje, S., Diedhiou, A., Kouassi, K. L., Ta, M. Y., Mortey, E. M., Roudier, P., et al. (2022). Analysis Of Hydroclimatic Trends And Variability And Their Impacts On hydropower generation in two river basins in Cote d'Ivoire (West Africa) during 1981-2017. Environmental Research Communications, 4(6).
Abstract: Climate change (CC) and variability impacts on hydroelectric generation have become critical for hydropower management. The trends of inflow, outflow, reservoir water level, and storage as well as hydraulicity indices of three main dams in Cote d'Ivoire, namely Kossou and Taabo in the Bandama basin and Buyo in the Sassandra basin were examined during 1981-2017 and their impacts on hydropower generation were analyzed. Moreover, the hydropower generation sensitivity to CC of these dams was assessed using statistical analysis. The results reveal that the inflow is highly dependent on rainfall while the water level is highly influenced by the outflow, which is a function of the inflow to the reservoirs and water management policy. Furthermore, the Mann Kendall test revealed that temperature and potential evapotranspiration have increased significantly in all three sub-basins while precipitation shows a significant upward trend only within the Taabo dam catchment area. Meanwhile, inflow to reservoir increased significantly and greatly than precipitation probably due to land use/cover change. Precipitation and inflow show a strong correlation as energy generation is significantly and strongly correlated to outflow (inflow) in all stations (except Kossou). Furthermore, the energy generation at Buyo and Taabo dams is more sensitive to reservoir inflow, while that of Kossou dam is more affected by water level. In addition, the power of a given year is also dependent on the total rainfall of that year and/or the previous year depending on the plant.
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Obahoundje, S., N'Guessan, V., Diedhiou, A., Kravitz, B., & Moore, J. (2022). Influence Of Stratospheric Aerosol Geoengineering On Temperature Mean And Precipitation Extremes Indices In Africa. International Journal Of Climate Change Strategies And Management, 141(4), 399–423.
Abstract: Purpose Three Coupled Model Intercomparison Project Phase 5 Models Involved In The G4 Experiment Of The Geoengineering Model Inter-Comparison Project (Geomip) Project Were Used To Investigate The Impact Of Stratospheric Aerosol Injection (Sai) On The Mean Surface Air Temperature And Precipitation Extremes In Africa. Design/Methodology/Approach This Impact Was Examined Under G4 And Representative Concentration Pathway (Rcp) 4.5 Scenarios On The Total Precipitation, The Number Of Rainy Days (Rr1) And Of Days With Heavy Rainfall (R20 Mm), The Rainfall Intensity (Sdii), The Maximum Length Of Consecutive Wet (Cwd) And Dry (Cdd) Days And On The Maximum Rainfall In Five Consecutive Days (Rx5Day) Across Four Regions: Western Africa (Waf), Eastern Africa (Eaf), Northern Africa And Southern Africa (Saf). Findings During The 50 Years (2020-2069) Of Sai, Mean Continental Warming Is -0.40 Degrees C Lower In G4 Than Under Rcp4.5. During The Post-Injection Period (2070-2090), The Temperature Continues To Increase, But At A Lower Rate (-0.19 Degrees C) Than In Rcp4.5. During Sai, Annual Rainfall In G4 Is Significantly Greater Than In Rcp4.5 Over The High Latitudes (Especially Over Saf) And Lower Over The Tropics. The Termination Of Sai Leads To A Significant Increase Of Rainfall Over Sahel And Eaf And A Decrease Over Saf And Guinea Coast (Waf). Practical Implications Compared To Rcp4.5, Sai Will Contribute To Reducing Significantly Regional Warming But With A Significant Decrease Of Rainfall In The Tropics Where Rainfed Agriculture Account For A Large Part Of The Economies. After The Sai Period, The Risk Of Drought Over The Extratropical Regions (Especially In Saf) Will Be Mitigated, While The Risk Of Floods Will Be Exacerbated In The Central Sahel. Originality/Value To Meet The Paris Agreement, African Countries Will Implement Mitigation Measures To Contribute To Keep The Surface Air Temperature Below 2 Degrees C. Geoengineering With Sai Is Suggested As An Option To Meet This Challenge, But Its Implication On The African Climate System Needs A Deep Investigation In The Aim To Understand The Impacts On Temperature And Precipitation Extremes. To The Best Of The Authors' Knowledge, This Study Is The First To Investigate The Potential Impact Of Sai Using The G4 Experiment Of Geomip On Temperature And Precipitation Extremes Of The African Continent.
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Olmo, M. E., Espinoza, J. C., Bettolli, M. L., Sierra, J. P., Junquas, C., Arias, P. A., et al. (2022). Circulation Patterns And Associated Rainfall Over South Tropical South America: GCMs Evaluation During the Dry-To-Wet Transition Season. Journal Of Geophysical Research-Atmospheres, 1271(121).
Abstract: The representation of the South American Monsoon System (SAMS) by general circulation models (GCMs) is of key relevance for a better understanding of the physical rationale behind the recent climate changes over South Tropical South America (STSA) and their expected changes in a global warming scenario. During the last four decades, STSA experienced a lengthening of the dry season associated with diverse forcings. In this work, a set of 16 GCMs historical Coupled Model Intercomparison Project Phase 6 coupled simulations were evaluated during 1979-2014 in terms of how well they reproduced the atmospheric circulation over STSA through a circulation-patterns (CPs) approach. Nine CPs were first identified based on low-level winds from the ERA5 reanalysis. Focus was put on the representation of CPs during the dry-to-wet transition season (July-October). Model performance depended on the seasonal cycle and spatial structure of the CPs. GCMs adequately reproduced the different CPs, with lower skills in the transition seasons. GCMs tended to go from dry to wet conditions too quickly, evidencing deficiencies in the representation of the SAMS onset, related to a poor representation of the southerly wind intrusions to STSA and the variability of the South American low-level jet. Some GCMs were able to associate the occurrence of anomalous dry and wet years with specific CPs, suggesting well-represented physical mechanisms controlling precipitation variability. This study could identify a few GCMs that adequately simulated the CPs in STSA (among them, CESM2, CMCC-CM2-HR4 and MPI-ESM1-2-HR), which is relevant for driving high-resolution models and the analysis of future projections.
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Oyabu, I., Kawamura, K., Buizert, C., Parrenin, F., Orsi, A., Kitamura, K., et al. (2022). The Dome Fuji Ice Core Df2021 Chronology (0-207 Kyr Bp). Quaternary Science Reviews, .
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Papazian, S., D'Agostino, L. A., Sadiktsis, I., Froment, J., Bonnefille, B., Sdougkou, K., et al. (2022). Nontarget mass spectrometry and in silico molecular characterization of air pollution from the Indian subcontinent. Communications Earth & Environment, 3(1).
Abstract: A combination of high-resolution mass spectrometry and computational molecular characterization techniques can structurally annotate up to 17% of organic compounds in fine particulate matter in highly polluted air sampled in the Maldives. Fine particulate-matter is an important component of air pollution that impacts health and climate, and which delivers anthropogenic contaminants to remote global regions. The complex composition of organic molecules in atmospheric particulates is poorly constrained, but has important implications for understanding pollutant sources, climate-aerosol interactions, and health risks of air pollution exposure. Here, comprehensive nontarget high-resolution mass spectrometry was combined with in silico structural prediction to achieve greater molecular-level insight for fine particulate samples (n = 40) collected at a remote receptor site in the Maldives during January to April 2018. Spectral database matching identified 0.5% of 60,030 molecular features observed, while a conservative computational workflow enabled structural annotation of 17% of organic structures among the remaining molecular dark matter. Compared to clean air from the southern Indian Ocean, molecular structures from highly-polluted regions were dominated by organic nitrogen compounds, many with computed physicochemical properties of high toxicological and climate relevance. We conclude that combining nontarget analysis with computational mass spectrometry can advance molecular-level understanding of the sources and impacts of polluted air.
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Pellarin, T., Zoppis, A., Roman-Cascon, C., Kerr, Y. H., Rodriguez-Fernandez, N., Panthou, G., et al. (2022). From SMOS Soil Moisture to 3-hour Precipitation Estimates at 0.1 degrees Resolution in Africa. Remote Sensing, 141(3).
Abstract: Several recent studies have shown that knowledge of the spatiotemporal dynamics of soil moisture intrinsically contains information on precipitation. In this study, we show how SMOS measurements can be used to generate a near-real-time precipitation product with a spatial resolution of 0.1 degrees and a temporal resolution of 3 h. The principle consists of assimilating the SMOS data into a model that simulates the evolution of soil moisture, which is forced by a satellite precipitation product. The assimilation of SMOS soil moisture leads to an adjustment of the satellite precipitation rates. Using data from more than 200 rain gauges set up in Africa between 2010 and 2021, we show that the PrISM algorithm (for Precipitation Inferred from Soil Moisture) almost systematically improves the initial precipitation product. One of the original features of this study is that we used the IMERG-Early satellite precipitation product, which has a finer spatial resolution (0.1 degrees) than SMOS (~0.25 degrees). Despite this, the methodology reduces both the RMSE and bias of IMERG-Early. The RMSE is reduced from 8.0 to 6.3 mm/day, and the absolute bias is reduced from 0.81 to 0.63 mm/day on average over the 200 rain gauges. PrISM performs even slightly better on average than IMERG-Final in terms of RMSE (6.8 mm/day for IMERG-Final) but better scores are obtained by IMERG-Final in terms of absolute bias (0.35 mm/day), which utilizes a network of field measurements to correct the biases of the IMERG-Early product with a 2.5-month delay. Therefore, the use of SMOS soil moisture measurements for Africa can be an advantageous alternative to the use of gauge measurements for debiasing rainfall satellite products in real time.
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Pelletier, C., Fichefet, T., Goosse, H., Haubner, K., Helsen, S., Huot, P. V., et al. (2022). PARASO, a circum-Antarctic fully coupled ice-sheet-ocean-sea-ice-atmosphere-land model involving f.ETISh1.7, NEMO3.6, LIM3.6, COSM05.0 and CLM4.5. Geoscientific Model Development, 151(2), 553–594.
Abstract: We introduce PARASO, a novel five-component fully coupled regional climate model over an Antarctic circumpolar domain covering the full Southern Ocean. The state-of-the-art models used are the fast Elementary Thermomechanical Ice Sheet model (f.ETISh) v1.7 (ice sheet), the Nucleus for European Modelling of the Ocean (NEMO) v3.6 (ocean), the Louvain-la-Neuve sea-ice model (LIM) v3.6 (sea ice), the COnsortium for Small-scale MOdeling (COSMO) model v5.0 (atmosphere) and its CLimate Mode (CLM) v4.5 (land), which are here run at a horizontal resolution close to 1/4 degrees. One key feature of this tool resides in a novel two-way coupling interface for representing ocean- ice-sheet interactions, through explicitly resolved ice-shelf cavities. The impact of atmospheric processes on the Antarctic ice sheet is also conveyed through computed COSMO-CLM-f.ETISh surface mass exchange. In this technical paper, we briefly introduce each model's configuration and document the developments that were carried out in order to establish PARASO. The new offline-based NEMO-f.ETISh coupling interface is thoroughly described. Our developments also include a new surface tiling approach to combine open-ocean and sea-ice-covered cells within COSMO, which was required to make this model relevant in the context of coupled simulations in polar regions. We present results from a 2000-2001 coupled 2-year experiment. PARASO is numerically stable and fully operational. The 2-year simulation conducted without fine tuning of the model reproduced the main expected features, although remaining systematic biases provide perspectives for further adjustment and development.
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Philippon, N., Ouhechou, A., Camberlin, P., Trentmann, J., Fink, A. H., Maloba, J. D., et al. (2022). Characterization Of Sunshine Duration In Western Equatorial Africa: In Situ Measurements versus SARAH-2 Satellite Estimates. Journal Of Applied Meteorology And Climatology, 616(2), 185–201.
Abstract: Western Equatorial Africa is one of the least sunny areas in the world. Yet, this has attracted little research so far. As in many other parts of Africa, light availability is mainly estimated using in situ measurements of sunshine duration (SDU). Therefore, this study conducts the first characterization of SDU evolution during the annual cycle for the region. It also evaluates the skill of satellite-based estimates of SDU from the Surface Solar Radiation Data Set-Heliosat, edition 2.1 (SARAH-2.1). Mean annual SDU levels are low: less than 5 h day21 at the regional scale, with the sunniest stations in the northeast (Cameroon and Central African Republic) and the least sunny in an similar to 150-km-wide coastal strip in Gabon and Republic of the Congo (RoC). For most of the stations except the southeast ones in the Democratic Republic of Congo, the lowest SDU levels are recorded in July-September, during the main dry season, with persistent overcast conditions. They are as low as 2.5 h day21, especially on the windward slopes of the Massifs du Chaillu and du Mayombe, nd of the Bateke Plateaus in Gabon and RoC. Although the mean annual and monthly spatial patterns are well reproduced in SARAH-2.1, SDU levels are systematically overestimated by 1-2 h day21. The largest positive biases are recorded during the December-February dry season, especially at the northernmost stations. Analyses at the daily time scale show that SARAH-2.1 biases arise from a twofold problem: the number of dark days (SDU, 1 h day21) is 50% lower than observed whereas that of sunny days (SDU. 9 h day21) is 50% higher than observed.
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Piantini, M., Gimbert, F., Bakker, M., Recking, A., & Nanni, U. (2022). Using A Dense Seismic Array To Study Fluvial Processes In A Braided river reach under flood conditions. Lhb-Hydroscience Journal, , 2053314.
Abstract: Dense seismic array monitoring has recently allowed the detailed investigation of sources of ground vibrations and their spatiotemporal dynamics. In a context where traditional monitoring techniques for fluvial processes often do not provide data with adequate temporal and spatial resolution, the use of dense arrays could allow the identification and tracking of different sources of river-induced seismic ground vibrations (e.g. turbulence and bedload transport). Here, we study the potential of dense seismic array monitoring by investigating a high-flow event that occurred in summer 2019 along a 600-m-long braided reach of the Severaisse River (French Alps). We use a network of 80 seismometers deployed on both river banks, and we supplement the seismic observations with flow gauging measurements and time-lapse imagery. During this event, we observe impulsive signals that are coherently detected over the array, and which we interpret as being associated with the bedload transport of clusters of coarse grains (blocks). Through phase-delay analysis we are able to locate these seismic events on the bend apex of an active branch of the reach. These results demonstrate the capability of such a method to locate bedload activity at high spatiotemporal resolution, providing crucial information for geomorphological investigations and natural risk management.
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Piantini, M., Gimbert, F., Bakker, M., Recking, A., & Nanni, U. (2022). Using A Dense Seismic Array To Study Fluvial Processes In A Braided river reach under flood conditions. Lhb-Hydroscience Journal, .
Abstract: Dense seismic array monitoring has recently allowed the detailed investigation of sources of ground vibrations and their spatiotemporal dynamics. In a context where traditional monitoring techniques for fluvial processes often do not provide data with adequate temporal and spatial resolution, the use of dense arrays could allow the identification and tracking of different sources of river-induced seismic ground vibrations (e.g. turbulence and bedload transport). Here, we study the potential of dense seismic array monitoring by investigating a high-flow event that occurred in summer 2019 along a 600-m-long braided reach of the Severaisse River (French Alps). We use a network of 80 seismometers deployed on both river banks, and we supplement the seismic observations with flow gauging measurements and time-lapse imagery. During this event, we observe impulsive signals that are coherently detected over the array, and which we interpret as being associated with the bedload transport of clusters of coarse grains (blocks). Through phase-delay analysis we are able to locate these seismic events on the bend apex of an active branch of the reach. These results demonstrate the capability of such a method to locate bedload activity at high spatiotemporal resolution, providing crucial information for geomorphological investigations and natural risk management.
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Picard, G., Leduc-Leballeur, M., Banwell, A., Brucker, L., & Macelloni, G. (2022). The Sensitivity Of Satellite Microwave Observations To Liquid Water In The Antarctic Snowpack. Cryosphere, 161(121), 5061–5083.
Abstract: Surface Melting On The Antarctic Ice Sheet Has Been Monitored By Satellite Microwave Radiometry For Over 40 Years. Despite This Long Perspective, Our Understanding Of The Microwave Emission From Wet Snow Is Still Limited, Preventing The Full Exploitation Of These Observations To Study Supraglacial Hydrology. Using The Snow Microwave Radiative Transfer (Smrt) Model, This Study Investigates The Sensitivity Of Microwave Brightness Temperature To Snow Liquid Water Content At Frequencies From 1.4 To 37 Ghz. We First Determine The Snowpack Properties For Eight Selected Coastal Sites By Retrieving Profiles Of Density, Grain Size And Ice Layers From Microwave Observations When The Snowpack Is Dry During Wintertime. Second, A Series Of Brightness Temperature Simulations Is Run With Added Water. The Results Show That (I) A Small Quantity Of Liquid Water (P-Center Dot 0.5 Kgm(-2)) Can Be Detected, But The Actual Quantity Cannot Be Retrieved Out Of The Full Range Of Possible Water Quantities; (Ii) The Detection Of A Buried Wet Layer Is Possible Up To A Maximum Depth Of 1 To 6 M Depending On The Frequency (6-37 Ghz) And On The Snow Properties (Grain Size, Density) At Each Site; (Iii) Surface Ponds And Water-Saturated Areas May Prevent Melt Detection, But The Current Coverage Of These Waterbodies In The Large Satellite Field Of View Is Presently Too Small In Antarctica To Have Noticeable Effects; And (Iv) At 1.4 Ghz, While The Simulations Are Less Reliable, We Found A Weaker Sensitivity To Liquid Water And The Maximal Depth Of Detection Is Relatively Shallow (< 10 M) Compared To The Typical Radiation Penetration Depth In Dry Firn (Asymptotic To 1000 M) At This Low Frequency. These Numerical Results Pave The Way For The Development Of Improved Multi Frequency Algorithms To Detect Melt Intensity And The Depth Of Liquid Water Below The Surface In The Antarctic Snowpack.
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Picard, G., Lowe, H., Domine, F., Arnaud, L., Larue, F., Favier, V., et al. (2022). The Microwave Snow Grain Size: A New Concept To Predict Satellite Observations Over Snow-Covered Regions. Agu Advances, 3(4).
Abstract: Satellite observations of snow-covered regions in the microwave range have the potential to retrieve essential climate variables such as snow height. This requires a precise understanding of how microwave scattering is linked to snow microstructural properties (density, grain size, grain shape and arrangement). This link has so far relied on empirical adjustments of the theories, precluding the development of robust retrieval algorithms. Here we solve this problem by introducing a new microstructural parameter able to consistently predict scattering. This “microwave grain size” is demonstrated to be proportional to the measurable optical grain size and to a new factor describing the chord length dispersion in the microstructure, a geometrical property known as polydispersity. By assuming that the polydispersity depends on the snow grain type only, we retrieve its value for rounded and faceted grains by optimization of microwave satellite observations in 18 Antarctic sites, and for depth hoar in 86 Canadian sites using ground-based observations. The value for the convex grains (0.6) compares favorably to the polydispersity calculated from 3D micro-computed tomography images for alpine grains, while values for depth hoar show wider variations (1.2-1.9) and are larger in Canada than in the Alps. Nevertheless, using one value for each grain type, the microwave observations in Antarctica and in Canada can be simulated from in-situ measurements with good accuracy with a fully physical model. These findings improve snow scattering modeling, enabling future more accurate uses of satellite observations in snow hydrological and meteorological applications.
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Picard, G., Lowe, H., & Matzler, C. (2022). Brief Communication: A Continuous Formulation Of Microwave Scattering From Fresh Snow To Bubbly Ice From First Principles. Cryosphere, 161(9), 3861–3866.
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Prieur, C., Rabatel, A., Thomas, J., Farup, I., & Chanussot, J. (2022). Machine Learning Approaches To Automatically Detect Glacier Snow Lines On Multi-Spectral Satellite Images. Remote Sensing, 141(161).
Abstract: Documenting The Inter-Annual Variability And The Long-Term Trend Of The Glacier Snow Line Altitude Is Highly Relevant To Document The Evolution Of Glacier Mass Changes. Automatically Identifying The Snow Line On Glaciers Is Challenging; Recent Developments In Machine Learning Approaches Show Promise To Tackle This Issue. This Manuscript Presents A Proof Of Concept Of Machine Learning Approaches Applied To Multi-Spectral Images To Detect The Snow Line And Quantify Its Average Altitude. The Tested Approaches Include The Combination Of Different Image Processing And Classification Methods, And Takes Into Account Cast Shadows. The Efficiency Of These Approaches Is Evaluated On Mountain Glaciers In The European Alps By Comparing The Results With Manually Annotated Data. Solutions Provided By The Different Approaches Are Robust When Compared To The Ground Truth'S Snow Lines, With A Pearson'S Correlation Ranging From 79% To 96% Depending On The Method. However, The Tested Approaches May Fail When Snow Lines Are Not Continuous Or Exhibit A Strong Change Of Elevation. The Major Advantage Over The State Of The Art Is That The Proposed Approach Does Not Require One Calibration Per Glacier.
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Racoviteanu, A. E., Glasser, N. F., Robson, B. A., Harrison, S., Millan, R., Kayastha, R. B., et al. (2022). Recent Evolution Of Glaciers In The Manaslu Region Of Nepal From Satellite Imagery and UAV Data (1970-2019). Frontiers In Earth Science, 9.
Abstract: Glacierized mountain ranges such as the Himalaya comprise a variety of glacier types, including clean and debris-covered glaciers. Monitoring their behaviour over time requires an assessment of changes in area and elevation along with surface features and geomorphology. In this paper we quantify the surface evolution of glacier systems in the Manaslu region of Nepal over the last five decades using 2013/2019 multi-sensor imagery and elevation data constructed from 1970 declassified Corona imagery and 1970 declassified Corona imagery. We investigate area changes, glacier thickness, geodetic glacier mass balance and surface velocity changes at regional scales and focus on the Ponkar Glacier and Thulagi Glacier and Lake for an in-depth assessment of surface geomorphology and surface feature dynamics (ponds, vegetation and ice cliffs). The time series of surface elevation changes for the lower ablation area of Ponkar Glacier is extended using 2019 UAV-based imagery and field-based ablation rates measured over the period 2016-2019. Glaciers in the Manaslu region experienced a mean area loss of -0.26 +/- 0.0001% a(-1) between 1970 and 2019. The mean surface lowering was -0.20 +/- 0.02 ma(-1) over the period 1970 to 2013, corresponding to a regional geodetic mass balance of -0.17 +/- 0.03 m w. e.a(-1). Overall, debris-covered glaciers had slightly higher thinning rates compared to clean ice glaciers; lake-terminating glaciers had double thinning rates compared to land-terminating glaciers. Individual glacier mass balance was negatively controlled by glacier slope and mean glacier elevation. During the period 1970 to 2013, Ponkar Glacier had a geodetic mass balance of -0.06 +/- 0.01 m w. e.a(-1), inversely correlated with parts of the central trunk thickening. Between 2013 and 2019 there was a nine-fold increase in the thinning rates over the lower parts of the glacier tongue relative to the period 1970-2013. Ice-surface morphology changes between 1970 and 2019 on Ponkar Glacier include a decrease in ogives and open crevasses, an increase in ice cliffs and ponds and the expansion of the supraglacial debris and ice-surface vegetation. These changes point to reduced ice-dynamic activity and are commensurate with the observed recession and negative glacier mass balance over the last five decades.
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Range, M., Arbic, B., Johnson, B., Moore, T., Titov, V., Adcroft, A., et al. (2022). The Chicxulub Impact Produced A Powerful Global Tsunami. Agu Advances, 3(5).
Abstract: The Chicxulub Crater Is The Site Of An Asteroid Impact Linked With The Cretaceous-Paleogene (K-Pg) Mass Extinction At Similar To 66 Ma. This Asteroid Struck In Shallow Water And Caused A Large Tsunami. Here We Present The First Global Simulation Of The Chicxulub Impact Tsunami From Initial Contact Of The Projectile To Global Propagation. We Use A Hydrocode To Model The Displacement Of Water, Sediment, And Crust Over The First 10 Min, And A Shallow-Water Ocean Model From That Point Onwards. The Impact Tsunami Was Up To 30,000 Times More Energetic Than The 26 December 2004 Indian Ocean Tsunami, One Of The Largest Tsunamis In The Modern Record. Flow Velocities Exceeded 20 Cm/S Along Shorelines Worldwide, As Well As In Open-Ocean Regions In The North Atlantic, Equatorial South Atlantic, Southern Pacific And The Central American Seaway, And Therefore Likely Scoured The Seafloor And Disturbed Sediments Over 10,000 Km From The Impact Origin. The Distribution Of Erosion And Hiatuses In The Uppermost Cretaceous Marine Sediments Are Consistent With Model Results.
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Ravanel, L., Lacroix, E., Le Meur, E., Batoux, P., & Malet, E. (2022). Multiparameter Monitoring Of Crevasses On An Alpine Glacier To Understand Formation And Evolution Of Snow Bridges. Cold Regions Science And Technology, 2032.
Abstract: On Glaciers, The Snow Bridges That Form Above Crevasses Have Hardly Been Considered By Researchers Up To Now, Despite Their Importance For High Mountain Activities (Skiing, Mountaineering) And The Risks That Their Possible Failure Poses To Practitioners. In Order To Improve Our Understanding Of The Formation And Evolution Of These Fragile Snow Structures, We Monitored During Two Years A Succession Of Three Crevasses Located At 3450 M A.S.L. In The Mont-Blanc Massif (France) Using A Set Of Sensors Including An Automatic Camera, Air Temperature Sensors, A Wind Vane-Anemometer, And An Extensometer. Geophysical Profiles (Ground Penetrating Radar) Were Also Carried Out To Clarify The Glacial Context. Despite Particularly Extreme Monitoring Conditions, At The Level Of A Bump Formed By The Bedrock Under An Ice Thickness Of C. 25 M, We Have Shown That A Wind Event Parallel To The Crevasse Favours Its Filling By Snow While A Strong Wind Making A Significant Angle With The Crevasse Under Largely Negative Temperatures Can Rapidly Create A Snow Bridge By Cornice Accretion That Grows By Extending Leeward. High Temperatures Are Responsible For Most Of The Natural Failures Of Sbs. These Elements Are Already Used For Risk Mitigation.
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Reveillet, M., Dumont, M., Gascoin, S., Lafaysse, M., Nabat, P., Ribes, A., et al. (2022). Black Carbon And Dust Alter The Response Of Mountain Snow Cover Under Climate Change. Nature Communications, 131(1).
Abstract: Black Carbon And Dust Deposition Advanced The End Of The Snow Season By 17 Days On Average Over The Last 40 Years In The French Alps And The Pyrenees. The Warming-Induced Snow Cover Decline Was Partly Offset By Decreases In Black Carbon Deposition Observed Since The 1980S. By Darkening The Snow Surface, Mineral Dust And Black Carbon (Bc) Deposition Enhances Snowmelt And Triggers Numerous Feedbacks. Assessments Of Their Long-Term Impact At The Regional Scale Are Still Largely Missing Despite The Environmental And Socio-Economic Implications Of Snow Cover Changes. Here We Show, Using Numerical Simulations, That Dust And Bc Deposition Advanced Snowmelt By 17 +/- 6 Days On Average In The French Alps And The Pyrenees Over The 1979-2018 Period. Bc And Dust Also Advanced By 10-15 Days The Peak Melt Water Runoff, A Substantial Effect On The Timing Of Water Resources Availability. We Also Demonstrate That The Decrease In Bc Deposition Since The 1980S Moderates The Impact Of Current Warming On Snow Cover Decline. Hence, Accounting For Changes In Light-Absorbing Particles Deposition Is Required To Improve The Accuracy Of Snow Cover Reanalyses And Climate Projections, That Are Crucial For Better Understanding The Past And Future Evolution Of Mountain Social-Ecological Systems.
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Rignot, E., Mouginot, J., Scheuchl, B., & Jeong, S. (2022). Changes In Antarctic Ice Sheet Motion Derived From Satellite Radar Interferometry Between 1995 And 2022. Geophysical Research Letters, 494(232).
Abstract: Ice Motion And Boundaries Are Critical Information For Ice Sheet Models That Project Ice Evolution In A Warming Climate. We Present Four Historical, Continent-Wide, Maps Of Antarctic-Wide Ice Motion And Boundaries For The Time Period 1995-2022. The Results Reveal No Change In The Interior Region Of East Antarctica, Iceberg Detachments At Ice Shelf Fronts, And Widespread Glacier Speedup That Propagates 100 Km'S Inland In West Antarctica And The Antarctic Peninsula. Speedup Affects The Entire Drainage Of The Amundsen Sea Embayment Sector; The Entire West Coast Of The Antarctic Peninsula Down To Georgevi Ice Shelf; The East Coast Down To Larsen C Ice Shelf; Getz Ice Shelf, Hull And Land Glaciers In West Antarctica; Matusevitch, Ninnis, Mertz And Denman Glaciers, Glaciers In Porpoise And Vincennes Bay; And Robert, Wilma And Rayner Glaciers In Enderby Land, In East Antarctica. We Attribute The Observed Glacier Changes To Increased Melting By Warmer Ocean Waters.
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Rindraharisaona, E., Rechou, A., Fontaine, F., Barruol, G., Stamenoff, P., Boudevillain, B., et al. (2022). Seismic Signature Of Rain And Wind Inferred From Seismic Data. Earth And Space Science, 9(101).
Abstract: Seismic Stations Are Increasingly Used To Monitor River Activity And To Quantify Sediment Transport During Flood Events. In Tropical Regions, Cyclone-Induced Floods Are Often Associated With Heavy Rain And Strong Wind Episodes, Generating Complex Seismic Records Involving The Simultaneous Signature Of Water, Sediment, Rainfall And Wind. Hence, Seismic Characterization Of Rain And Wind Is Then Required To Better Decipher Each Process And Improve Our Understanding Of The River Seismic Signature. In This Study, We Investigate Experimentally The Seismic Response Of Rain And Wind Using Data Recorded By Geophones Deployed In Various Soil Types And At Different Burial Depth (Bd), Co-Located With Various Meteorological Instruments. Our Results Show That The Power Spectral Density (Psd) Of The Seismic Noise Intensifies At A Frequency Between 60 And 500 Hz For Rain And 5 And 500 Hz For Wind, In The Presence Of Rain Precipitation As Low As 0.025 Mm/Min And/Or Wind Speed >= 3 M/S. Psd Analysis Indicates That The Seismic Signal Associated With Rain Decreases With The Bd With A Value Of Similar To 2-5 Db In A Depth Difference Of 10 Cm. We Also Observe That Each Soil Type Has Its Own Seismic Signature. The 4-Min Root Mean Square Correlation Between The Seismic Signal Amplitude And The Rain Precipitation Suggests That They Best Correlate With Pearson Coefficient >0.90 At Bd Of 30 Cm. The Transfer Function Between The Precipitation Rate (Or Kinetic Energy) And The Seismic Signal Amplitude Shows That The Signal Recorded By The Geophone Can Be Used As A Robust Proxy For These Parameters. Plain Language Summary In Addition To Recording Deep Earth Activity Such As Earthquakes Or Volcanic Eruptions, Seismic Sensors Can Measure Numbers Of Naturally-Induced Ground Vibrations Such As Those Generated By Rivers Activities. In Tropical Areas During Cyclonic Events, Heavy Rain (And Strong Wind) Leads To The Presence Of Severe Flooding, During Which Several Activities In And On The River (E.G., Sediment Transport, Wind, Water, And Rain) Generate Ground Vibration, Making The Overall Signals Recorded By Seismic Sensors Complex To Interpret. To Better Decipher The River Seismic Signature, Investigating The Wind And Rain Signatures Are Then Essential. In This Study, We Investigate Experimentally The Seismic Response Of Rain And Wind From Data Recorded By Geophones And Complemented By Different Meteorological Sensors. The Obtained Results Show That (A) The Strength Of The Seismic Noise Intensifies With Frequency For Rain And Wind; (B) The Seismic Signal Associated With Rain Decreases With The Burying Depth Of The Sensor; (C) The Amplitude Of The Seismic Signal Correlates With Rain Precipitation When The Sensor Is Well Buried And (D) The Signal Recorded By The Geophone Can Be Used As A Robust Proxy For Rain Precipitation.
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Rivoire, P., Le Gall, P., Favre, A., Naveau, P., & Martius, O. (2022). High Return Level Estimates Of Daily Era-5 Precipitation In Europe Estimated Using Regionalized Extreme Value Distributions. Weather And Climate Extremes, 383.
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Robledano, A., Picard, G., Arnaud, L., Larue, F., & Ollivier, I. (2022). Modelling surface temperature and radiation budget of snow-covered complex terrain. Cryosphere, 161(2), 559–579.
Abstract: The surface temperature controls the temporal evolution of the snowpack, playing a key role in metamorphism and snowmelt. It shows large spatial variations in mountainous areas because the surface energy budget is affected by the topography, for instance because of the modulation of the short-wave irradiance by the local slope and the shadows and the short-wave and long-wave re-illumination of the surface from surrounding slopes. These topographic effects are often neglected in large-scale models considering the surface to be flat and smooth. Here we aim at estimating the surface temperature of snow-covered mountainous terrain in clear-sky conditions in order to evaluate the relative importance of the different processes that control the spatial variations. For this, a modelling chain is implemented to compute the surface temperature in a kilometre-wide area from local radiometric and meteorological measurements at a single station. The first component of this chain is the Rough Surface Ray-Tracing (RSRT) model. Based on a photon transport Monte Carlo algorithm, this model quantifies the incident and reflected short-wave radiation on every facet of the mesh describing the snow-covered terrain. The second component is a surface scheme that estimates the terms of the surface energy budget from which the surface temperature is eventually estimated. To assess the modelling chain performance, we use in situ measurements of surface temperature and satellite thermal observations (Landsat 8) in the Col du Lautaret area, in the French Alps. The results of the simulations show (i) an agreement between the simulated and measured surface temperature at the station for a diurnal cycle in winter within 0.2 degrees C; (ii) that the spatial variations in surface temperature are on the order of 5 to 10 degrees C in the domain and are well represented by the model; and (iii) that the topographic effects ranked by importance are the modulation of solar irradiance by the local slope, followed by the altitudinal variations in air temperature (lapse rate), the re-illumination by long-wave thermal emission from surrounding terrain, and the spectral dependence of snow albedo. The changes in the downward long-wave flux because of variations in altitude and the absorption enhancement due to multiple bounces of photons in steep terrain play a less significant role. These results show the necessity of considering the topography to correctly assess the energy budget and the surface temperature of snow-covered complex terrain.
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Rocco, M., Baray, J. L., Colomb, A., Borbon, A., Dominutti, P., Tulet, P., et al. (2022). High Resolution Dynamical Analysis Of Volatile Organic. Compounds (Voc) Measurements During the BIO-MAIDO Field Campaign (Reunion Island, Indian Ocean). Journal Of Geophysical Research-Atmospheres, 1271(4).
Abstract: This study presents a high-resolution dynamical analysis of Volatile Organic Compound (VOC) concentrations measured from March 11 to April 4 2019 at Reunion Island during the BIO-MAIDO (Bio-physicochemistry of tropical clouds at Maido: processes and impacts on secondary organic aerosols formation) campaign. We detail the dynamical and chemical processes that govern atmospheric VOC concentrations at two targeted sites of the western slope of Reunion Island: Petite France (PF), 950 m above sea level (a.s.l.) and Maido Observatory (MO), 2150 m a.s.l. A dynamical connection between PF and MO is found during four selected days: March 28 and 31, April 1 and 3. Trajectory calculations using the coupling of Meso-Computing Advection-interpolation of atmospheric parameters and Trajectory tool (CAT) (100 m horizontal resolution of Meso-NH high-resolution non-hydrostatic model and the CAT trajectory model) Lagrangian transport model showed that air masses were dynamically linked between the two measurements sites for 19% of the time during the complete campaign. Trajectories from the Meso-CAT model combined with the Corine Land Cover-2018 register shows that backward-trajectories are frequently located above biogenic area (mixed forest, 3%-46% of total number trajectory point) and cultures area (e.g., sugar cane plantation, 1%-17%). Regarding VOCs concentrations, air masses coming from downhill MO are associated with significant measured concentrations of isoprene, isoprene oxidation products and benzene. Averaged concentration daytime ratios of isoprene and isoprene oxidation products from PF to MO are 0.73 +/- 1.01 and 0.26 +/- 0.26 respectively illustrating a loss of these VOCs due to deposition, oxidation, or possibility dilution on clouds.
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Rohmer, J., Thieblemont, R., Le Cozannet, G., Goelzer, H., & Durand, G. (2022). Improving Interpretation Of Sea-Level Projections Through A Machine-Learning-Based Local Explanation Approach. Cryosphere, 161(111), 4637–4657.
Abstract: Process-Based Projections Of The Sea-Level Contribution From Land Ice Components Are Often Obtained From Simulations Using A Complex Chain Of Numerical Models. Because Of Their Importance In Supporting The Decision-Making Process For Coastal Risk Assessment And Adaptation, Improving The Interpretability Of These Projections Is Of Great Interest. To This End, We Adopt The Local Attribution Approach Developed In The Machine Learning Community Known As “Shap” (Shapley Additive Explanations). We Apply Our Methodology To A Subset Of The Multi-Model Ensemble Study Of The Future Contribution Of The Greenland Ice Sheet To Sea Level, Taking Into Account Different Modelling Choices Related To (1) Numerical Implementation, (2) Initial Conditions, (3) Modelling Of Ice-Sheet Processes, And (4) Environmental Forcing. This Allows Us To Quantify The Influence Of Particular Modelling Decisions, Which Is Directly Expressed In Terms Of Sea-Level Change Contribution. This Type Of Diagnosis Can Be Performed On Any Member Of The Ensemble, And We Show In The Greenland Case How The Aggregation Of The Local Attribution Analyses Can Help Guide Future Model Development As Well As Scientific Interpretation, Particularly With Regard To Spatial Model Resolution And To Retreat Parametrisation.
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Rosales, A. G., Junquas, C., da Rocha, R. P., Condom, T., & Espinoza, J. C. (2022). Valley-Mountain Circulation Associated with the Diurnal Cycle of Precipitation in the Tropical Andes (Santa River Basin, Peru). Atmosphere, 131(2).
Abstract: The Cordillera Blanca (central Andes of Peru) represents the largest concentration of tropical glaciers in the world. The atmospheric processes related to precipitations are still scarcely studied in this region. The main objective of this study is to understand the atmospheric processes of interaction between local and regional scales controlling the diurnal cycle of precipitation over the Santa River basin located between the Cordillera Blanca and the Cordillera Negra. The rainy season (December-March) of 2012-2013 is chosen to perform simulations with the WRF (Weather Research and Forecasting) model, with two domains at 6 km (WRF-6 km) and 2 km (WRF-2 km) horizontal resolutions, forced by ERA5. WRF-2 km precipitation shows a clear improvement over WRF-6 km in terms of the daily mean and diurnal cycle, compared to in situ observations. WRF-2 km shows that the moisture from the Pacific Ocean is a key process modulating the diurnal cycle of precipitation over the Santa River basin in interaction with moisture fluxes from the Amazon basin. In particular, a channeling thermally orographic flow is described as controlling the afternoon precipitation along the Santa valley. In addition, in the highest parts of the Santa River basin (in both cordilleras) and the southern part, maximum precipitation occurs earlier than the lowest parts and the bottom of the valley in the central part of the basin, associated with the intensification of the channeling flow by upslope cross-valley winds during mid-afternoon and its decrease during late afternoon/early night.
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Saks, T., Pohl, E., Machguth, H., Dehecq, A., Barandun, M., Kenzhebaev, R., et al. (2022). Glacier Runoff Variation Since 1981 in the Upper Naryn River Catchments, Central Tien Shan. Frontiers In Environmental Science, 9.
Abstract: Water resources in Central Asia strongly depend on glaciers, which in turn adjust their size in response to climate variations. We investigate glacier runoff in the period 1981-2019 in the upper Naryn basin, Kyrgyzstan. The basins contain more than 1,000 glaciers, which cover a total area of 776 km(2). We model the mass balance and runoff contribution of all glaciers with a simplified energy balance melt model and distributed accumulation model driven by ERA5 LAND re-analysis data for the time period of 1981-2019. The results are evaluated against discharge records, satellite-derived snow cover, stake readings from individual glaciers, and geodetic mass balances. Modelled glacier volume decreased by approximately 6.7 km(3) or 14%, and the majority of the mass loss took place from 1996 until 2019. The decreasing trend is the result of increasingly negative summer mass balances whereas winter mass balances show no substantial trend. Analysis of the discharge data suggests an increasing runoff for the past two decades, which is, however only partly reflected in an increase of glacier melt. Moreover, the strongest increase in discharge is observed in winter, suggesting either a prolonged melting period and/or increased groundwater discharge. The average runoff from the glacierized areas in summer months (June to August) constitutes approximately 23% of the total contributions to the basin's runoff. The results highlight the strong regional variability in glacier-climate interactions in Central Asia.
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Saks, T., Pohl, E., Machguth, H., Dehecq, A., Barandun, M., Kenzhebaev, R., et al. (2022). Glacier Runoff Variation Since 1981 In The Upper Naryn River Catchments, Central Tien Shan (Vol 9, 780466, 2022). Frontiers In Environmental Science, 101.
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Sanchez-Cid, C., Tignat-Perrier, R., Franqueville, L., Delauriere, L., Schagat, T., & Vogel, T. M. (2022). Sequencing Depth Has a Stronger Effect than DNA Extraction on Soil Bacterial Richness Discovery. Biomolecules, 121(3).
Abstract: Although Next-Generation Sequencing techniques have increased our access to the soil microbiome, each step of soil metagenomics presents inherent biases that prevent the accurate definition of the soil microbiome and its ecosystem function. In this study, we compared the effects of DNA extraction and sequencing depth on bacterial richness discovery from two soil samples. Four DNA extraction methods were used, and sequencing duplicates were generated for each DNA sample. The V3-V4 region of the 16S rRNA gene was sequenced to determine the taxonomical richness measured by each method at the amplicon sequence variant (ASV) level. Both the overall functional richness and antibiotic resistance gene (ARG) richness were evaluated by metagenomics sequencing. Despite variable DNA extraction methods, sequencing depth had a greater influence on bacterial richness discovery at both the taxonomical and functional levels. Sequencing duplicates from the same sample provided access to different portions of bacterial richness, and this was related to differences in the sequencing depth. Thus, the sequencing depth introduced biases in the comparison of DNA extraction methods. An optimisation of the soil metagenomics workflow is needed in order to sequence at a sufficient and equal depth. This would improve the accuracy of metagenomic comparisons and soil microbiome profiles.
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Saunderson, D., Mackintosh, A., Mccormack, F., Jones, R., & Picard, G. (2022). Surface Melt On The Shackleton Ice Shelf, East Antarctica (2003-2021). Cryosphere, 161(101), 4553–4569.
Abstract: Melt On The Surface Of Antarctic Ice Shelves Can Potentially Lead To Their Disintegration, Accelerating The Flow Of Grounded Ice To The Ocean And Raising Global Sea Levels. However, The Current Understanding Of The Processes Driving Surface Melt Is Incomplete, Increasing Uncertainty In Predictions Of Ice Shelf Stability And Thus Of Antarctica'S Contribution To Sea-Level Rise. Previous Studies Of Surface Melt In Antarctica Have Usually Focused On Either A Process-Level Understanding Of Melt Through Energy-Balance Investigations Or Used Metrics Such As The Annual Number Of Melt Days To Quantify Spatiotemporal Variability In Satellite Observations Of Surface Melt. Here, We Help Bridge The Gap Between Work At These Two Scales. Using Daily Passive Microwave Observations From The Amsr-E And Amsr-2 Sensors And The Machine Learning Approach Of A Self-Organising Map, We Identify Nine Representative Spatial Distributions (“Patterns”) Of Surface Melt On The Shackleton Ice Shelf In East Antarctica From 2002/03-2020/21. Combined With Output From The Racmo2.3P3 Regional Climate Model And Surface Topography From The Rema Digital Elevation Model, Our Results Point To A Significant Role For Surface Air Temperatures In Controlling The Interannual Variability In Summer Melt And Also Reveal The Influence Of Localised Controls On Melt. In Particular, Prolonged Melt Along The Grounding Line Shows The Importance Of Katabatic Winds And Surface Albedo. Our Approach Highlights The Necessity Of Understanding Both Local And Large-Scale Controls On Surface Melt And Demonstrates That Self-Organising Maps Can Be Used To Investigate The Variability In Surface Melt On Antarctic Ice Shelves.
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Schmeller, D., Urbach, D., Bates, K., Catalan, J., Cogalniceanu, D., Fisher, M., et al. (2022). Scientists' Warning Of Threats To Mountains. Science Of The Total Environment, 8538.
Abstract: Mountains Are An Essential Component Of The Global Life-Support System. They Are Characterized By A Rugged, Heterog-Enous Landscape With Rapidly Changing Environmental Conditions Providing Myriad Ecological Niches Over Relativelysmall Spatial Scales. Although Montane Species Are Well Adapted To Life At Extremes, They Are Highly Vulnerable To Human Derived Ecosystem Threats. Here We Build On The Manifesto'World Scientists' Warning To Humanity',Issuedbythe Alliance Of World Scientists, To Outline The Major Threats To Mountain Ecosystems. We Highlight Climate Change Asthe Greatest Threat To Mountain Ecosystems, Which Are More Impacted Than Their Lowland Counterparts. We Further Dis-Cuss The Cascade Of“Knock-On”Effects Of Climate Change Such As Increased Uv Radiation, Altered Hydrological Cycles,And Altered Pollution Profiles; Highlighting The Biological And Socio-Economic Consequences. Finally, We Presenthow Intensified Use Of Mountains Leads To Overexploitation And Abstraction Of Water, Driving Changes In Carbonstock, Reducing Biodiversity, And Impacting Ecosystem Functioning. These Perturbations Can Provide Opportunitiesfor Invasive Species, Parasites And Pathogens To Colonize These Fragile Habitats, Driving Further Changes And Losses Ofmicro- And Macro-Biodiversity, As Well Further Impacting Ecosystem Services. Ultimately, Imbalances In The Normalfunctioning Of Mountain Ecosystems Will Lead To Changes In Vital Biological, Biochemical, And Chemical Processes, Crit-Ically Reducing Ecosystem Health With Widespread Repercussions For Animal And Human Wellbeing. Developing Tools Inspecies/Habitat Conservation And Future Restoration Is Therefore Essential If We Are To Effectively Mitigate Against The Declining Health Of Mountains
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Segura, H., Espinoza, J. C., Junquas, C., Lebel, T., Vuille, M., & Condom, T. (2022). Extreme austral winter precipitation events over the South-American Altiplano: regional atmospheric features. Climate Dynamics, .
Abstract: The South American Altiplano has a marked dry season during the austral winter (June to August, JJA). However, during this season synoptic meteorological conditions triggering heavy precipitation can damage socioeconomic activities, often causing the loss of human lives. Using daily in-situ precipitation data from 39 rain-gauge stations over the northern Altiplano (18 degrees S -15 degrees S; > 3000 m.a.s.l.) for the JJA season, we computed the historical percentile 90 (p90) and we identified extreme rainy days with precipitation higher than p90 in the 1980-2010 period. We identified 100 winter extreme precipitation events (WEPEs) over this region that can last between one to 16 days. The K-means analysis was applied to anomalies of geopotential height at 500 hPa from ERA-Interim data during the initial day or Day(0) of WEPEs lasting 1 day (42 cases), 2 days (19) and more than 2 days (39). We found 59 WEPEs characterized by an upper-level trough over the Peruvian-Chilean coast. At 850 hPa, these 59 WEPEs are also associated with cold surges along the eastern Central Andes, indicating an association between the upper-level trough and the cold surge in developing deep convection over the northern Altiplano. A lead-lag composite analysis further showed a significant lower- and mid-tropospheric moistening over the western Amazon 2 days before the onset of these 59 WEPEs, due to low-level northerly wind anomalies originating over equatorial South America. The other 41 WEPEs are associated with a low-level southerly wind regime crossing the equator and a mid-and upper-level low-pressure system over the Peruvian-Chilean coast. While the low-level southerly regime enhances mid-tropospheric moisture transport from the equator towards the Altiplano due to the developed shallow meridional circulation when propagating equatorward, a low-pressure system promotes intensification of upward motion, boosting the upslope moisture transport from the lowlands to the east of the Central Andes towards the Altiplano.
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Serrano-Vincenti, S., Condom, T., Campozano, L., Escobar, L., Walpersdorf, A., Carchipulla-Morales, D., et al. (2022). Harmonic Analysis Of The Relationship Between Gnss Precipitable Water Vapor And Heavy Rainfall Over The Northwest Equatorial Coast, Andes, And Amazon Regions. Atmosphere, 131(111).
Abstract: This Study Finds The Relationship Between Increases In Precipitable Water Vapor (Pwv), And Intense Rainfall Events In Four Different Climatological Regions Of South America'S Equatorial Northwest: The Coast, Andes Valley, High Mountains, And Amazon. First, The Pwv Was Derived From Tropospheric Zenith Delay Measured By Global Navigation Satellite System (Gnss) Instrumentation Located Near Meteorological Stations Within The Regions Of Interest Using Hourly Data From The Year 2014. A Harmonic Analysis Approach Through Continuous Wavelet Cross-Spectrum And Coherence, As Well As Discrete Wavelets, Was Used To Determine A Measure Of The Lags Found Between Pwv And Specific Heavy Rain Events And Then Compared With Satellite Ir Images And Meteorological Anomalies. The Link Between Pwv Peaks And Rainfall Was The Most Evident On The Coast, And Less Discernible In The Other Stations Possibly Due To Local Dynamic Factors. The Results Showed A Lag Of 11 H Between The Preceding Pwv Increase And An Intense Rainfall Event. This Was Apparent In All Of The Stations, Except In Amazon Where It Was 6 H, With The Highest Precision At The Coast And With The Largest Dispersion In The High Mountains. The Interpretation Of This Lag For Each Region Is Also Discussed.
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Shahne, M. Z., Arhami, M., El Haddad, I., Abbaszade, G., Schnelle-Kreis, J., Jaffrezo, J. L., et al. (2022). Particulate emissions of real-world light-duty gasoline vehicle fleet in Iran (vol 292, 118303, 2022). Environmental Pollution, 3003.
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Shangguan, Y. F., Zhuang, X. G., Querol, X., Li, B. Q., Moreno, N., Trechera, P., et al. (2022). Characterization Of Deposited Dust And Its Respirable Fractions In underground coal mines: Implications for oxidative potential-driving species and source apportionment. International Journal Of Coal Geology, 2582.
Abstract: Oxidative potential (OP) is considered to be an efficient indicator of particulate matter (PM) to induce oxidative stress in the lungs and is increasingly considered to be a relevant health metric. In this study, two complementary OP assays were deployed, including dithiothreitol (DTT) and ascorbic acid (AA) assays, to investigate the po-tential toxicity (as generators of oxidative stress) of respirable fractions (DD4, < 4 μm) of deposited dust (DD500, < 500 μm) in underground low-S and low-pyrite coal mines in Henan Province, Central China. The OPDTT of DD4 is higher than that reported for other types of atmospheric PM, whereas the OPAA of DD4 is similar and/or slightly higher. Cross-correlation and multilinear regression analyses are applied using datasets of major mineral and geochemical patterns in the DD4 samples and the respective OP values to identify the major drivers for OP in respirable coal dust. Thereafter, the patterns of DD4 are compared with those of DD500 and the parent coals to determine the sources of OP-relevant substances. OP(DTT )is mainly governed by some trace elements (Sb, As, Li, B, Sr, and Pb) and minor minerals (anatase, quartz, siderite), and their synergistic effect may be one of the reasons for the high DTT consumption. For OPAA, quartz, total clay (sum of illite, kaolinite, tobelite, and clinochlore) and Ni, Cr, Co, Si, and S, play an important role in regulating the OPAA of pyrite-free DD4 samples. These OP-relevant substances have three sources: coal dust, which has a similar composition in DD4, DD500, and the parent coal (such as siderite and its associated elements); gangue dust, which does not occur in the parent coal but is widely detected in DD4 and DD500 (such as quartz, kaolinite, and relevant elements); and cement dust (from gunite galleries), which is mainly calcite-and calcite-associated elements.
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Sharma, R., Chaudhary, A., Seemanth, M., Bhowmick, S. A., Agarwal, N., Verron, J., et al. (2022). SARAL/AltiKa data analysis for oceanographic research: Impact of drifting and post star sensor anomaly phases. Advances In Space Research, 696(6), 2349–2361.
Abstract: Y AltiKa, first ever high frequency Ka-band altimeter on board SARAL (Satellite with ARgos and ALtiKa) has gone through different phases of operations, viz. Exact Repeat Mission, (ERM, March 2013 – July 2016), Drifting phase, (DP, July 2016 – January 2018) and then to Mispointing phase, (MP, February 2018 – till date). A detailed assessment of Sea level anomaly (SLA), Significant Wave Height (SWH) and Ocean Surface Wind Speed (WS) has been carried out during these different phases with a focus on the North Indian Ocean. Crossover analysis using the Jason series of satellites available during various phases of SARAL suggest high quality of SARAL/AltiKa data during the ERM and DP with root mean square differences of the order of 0.080 m, 0.25 m and 1 m/s for SLA, SWH and WS respectively. These differences are more during MP, being 0.095 m, 0.45 m and 1.72 m/s for SLA, SWH and WS respectively. Wavenumber Power spectrum computed from the along-track AltiKa SLA reveals that slopes in the mesoscale band (70-250 km) in different phases of operations are not very different. Errors in gridded SARAL/AltiKa SLA with respect to standard AVISO product remains unchanged during DP, but degrade by nearly 9.3% in the MP as compared to ERM. To assess the effect of assimilating along track SWH and SLA from different phases, two set of wave and circulation model simulations, with and without SARAL AltiKa data assimilation, were performed. Assimilation of SWH improved the wave height simulation by similar to 12.8% during the DP and similar to 8% during ERM and MP. As regards to circulation modeling, no significant difference of assimilating SLA from different phases was observed in the mesoscale range. These results indicate the usefulness of SLA from SARAL AltiKa during DP and MP for studying the mesoscale dynamics. (C) 2021 COSPAR. Published by Elsevier B.V. All rights reserved.
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Shupe, M. D., Rex, M., Blomquist, B., Persson, P. O. G., Schmale, J., Uttal, T., et al. (2022). Overview of the MOSAiC expedition-Atmosphere INTRODUCTION. Elementa-Science Of The Anthropocene, 101(1).
Abstract: With the Arctic rapidly changing, the needs to observe, understand, and model the changes are essential. To support these needs, an annual cycle of observations of atmospheric properties, processes, and interactions were made while drifting with the sea ice across the central Arctic during the Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) expedition from October 2019 to September 2020. An international team designed and implemented the comprehensive program to document and characterize all aspects of the Arctic atmospheric system in unprecedented detail, using a variety of approaches, and across multiple scales. These measurements were coordinated with other observational teams to explore crosscutting and coupled interactions with the Arctic Ocean, sea ice, and ecosystem through a variety of physical and biogeochemical processes. This overview outlines the breadth and complexity of the atmospheric research program, which was organized into 4 subgroups: atmospheric state, clouds and precipitation, gases and aerosols, and energy budgets. Atmospheric variability over the annual cycle revealed important influences from a persistent large-scale winter circulation pattern, leading to some storms with pressure and winds that were outside the interquartile range of past conditions suggested by long-term reanalysis. Similarly, the MOSAiC location was warmer and wetter in summer than the reanalysis climatology, in part due to its close proximity to the sea ice edge. The comprehensiveness of the observational program for characterizing and analyzing atmospheric phenomena is demonstrated via a winter case study examining air mass transitions and a summer case study examining vertical atmospheric evolution. Overall, the MOSAiC atmospheric program successfully met its objectives and was the most comprehensive atmospheric measurement program to date conducted over the Arctic sea ice. The obtained data will support a broad range of coupled-system scientific research and provide an important foundation for advancing multiscale modeling capabilities in the Arctic.
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Siahaan, A., Smith, R., Holland, P., Jenkins, A., Gregory, J., Lee, V., et al. (2022). The Antarctic Contribution To 21St-Century Sea-Level Rise Predicted By The Uk Earth System Model With An Interactive Ice Sheet. Cryosphere, 161(101), 4053–4086.
Abstract: The Antarctic Ice Sheet Will Play A Crucial Role In The Evolution Of Global Mean Sea Level As The Climate Warms. An Interactively Coupled Climate And Ice Sheet Model Is Needed To Understand The Impacts Of Ice-Climate Feed-Backs During This Evolution. Here We Use A Two-Way Coupling Between The Uk Earth System Model And The Bisicles (Berkeley Ice Sheet Initiative For Climate At Extreme Scales) Dynamic Ice Sheet Model To Investigate Antarctic Ice-Climate Interactions Under Two Climate Change Scenarios. We Perform Ensembles Of Ssp1-1.9 And Ssp5-8.5 (Shared Socioeconomic Pathway) Scenario Simulations To 2100, Which We Believe Are The First Such Simulations With A Climate Model That Include Two-Way Coupling Of Atmosphere And Ocean Models To Dynamic Models Of The Greenland And Antarctic Ice Sheets. We Focus Our Analysis On The Latter. In Ssp1-1.9 Simulations, Ice Shelf Basal Melting And Grounded Ice Mass Loss From The Antarctic Ice Sheet Are Generally Lower Than Present Rates During The Entire Simulation Period. In Contrast, The Responses To Ssp5-8.5 Forcing Are Strong. By The End Of The 21St Century, These Simulations Feature Order-Of-Magnitude Increases In Basal Melting Of The Ross And Filchner-Ronne Ice Shelves, Caused By Intrusions Of Masses Of Warm Ocean Water. Due To The Slow Response Of Ice Sheet Drawdown, This Strong Melting Does Not Cause A Substantial Increase In Ice Discharge During The Simulations. The Surface Mass Balance In Ssp5-8.5 Simulations Shows A Pattern Of Strong Decrease On Ice Shelves, Caused By Increased Melting, And Strong Increase On Grounded Ice, Caused By Increased Snowfall. Despite Strong Surface And Basal Melting Of The Ice Shelves, Increased Snowfall Dominates The Mass Budget Of The Grounded Ice, Leading To An Ensemble Mean Antarctic Contribution To Global Mean Sea Level Of A Fall Of 22 Mm By 2100 In The Ssp5-8.5 Scenario. We Hypothesise That This Signal Would Revert To Sea-Level Rise On Longer Timescales, Caused By The Ice Sheet Dynamic Response To Ice Shelf Thinning These Results Demonstrate The Need For Fully Coupled Ice-Climate Models In Reducing The Substantial Uncertainty In Sea-Level Rise From The Antarctic Ice Sheet.
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Smith, A., Jahn, A., Burgard, C., & Notz, D. (2022). Improving Model-Satellite Comparisons Of Sea Ice Melt Onset With A Satellite Simulator. Cryosphere, 161(8), 3235–3248.
Abstract: Seasonal Transitions In Arctic Sea Ice, Such As The Melt Onset, Have Been Found To Be Useful Metrics For Evaluating Sea Ice In Climate Models Against Observations. However, Comparisons Of Melt Onset Dates Between Climate Models And Satellite Observations Are Indirect. Satellite Data Products Of Melt Onset Rely On Observed Brightness Temperatures, While Climate Models Do Not Currently Simulate Brightness Temperatures, And Must Therefore Define Melt Onset With Other Modeled Variables. Here We Adapt A Passive Microwave Sea Ice Satellite Simulator, The Arctic Ocean Observation Operator (Arc3O), To Produce Simulated Brightness Temperatures That Can Be Used To Diagnose The Timing Of The Earliest Snowmelt In Climate Models, As We Show Here Using Community Earth System Model Version 2 (Cesm2) Ocean-Ice Hindcasts. By Producing Simulated Brightness Temperatures And Earliest Snowmelt Estimation Dates Using Cesm2 And Arc3O, We Facilitate New And Previously Impossible Comparisons Between The Model And Satellite Observations By Removing The Uncertainty That Arises Due To Definition Differences. Direct Comparisons Between The Model And Satellite Data Allow Us To Identify An Early Bias Across Large Areas Of The Arctic At The Beginning Of The Cesm2 Ocean-Ice Hindcast Melt Season, As Well As Improve Our Understanding Of The Physical Processes Underlying Seasonal Changes In Brightness Temperatures. In Particular, The Arc3O Allows Us To Show That Satellite Algorithm-Based Melt Onset Dates Likely Occur After Significant Snowmelt Has Already Taken Place.
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Soriot, C., Picard, G., Prigent, C., Frappart, F., & Domine, F. (2022). Year-Round Sea Ice And Snow Characterization From Combined Passive And active microwave observations and radiative transfer modeling. Remote Sensing Of Environment, 2782.
Abstract: Satellite microwave observations from 1.4 to 36 GHz already showed sensitivity to several geophysical parameters of sea ice such as Sea Ice Concentration (SIC), Sea Ice Thickness (SIT) or snow depth. The main goal of this article is to provide a realistic and comprehensive characterization of the sea ice and its snow cover that explains the microwave observations during a whole year using a radiative transfer model. For this purpose, we construct a unique dataset of passive microwave observations, to mimic the future Copernicus Imaging Microwave Radiometer (CIMR), along with the active microwave scatterometer data (ASCAT). CIMR database is used to classify sea ice microwave signatures in their spectral dimension with a machine learning technique while ASCAT data are used to help interpret the results of the classification. Classification results are then interpreted with a state-of-art sea ice and Snow Microwave Radiative Transfer model (SMRT) for all highlighted signatures and all seasons. Results make it possible to identify the specific behaviors from the observation co-variabilities for SIC, SIT, and snow structure. Our analysis underlined the role of the depth hoar over multi-year ice, for the interpretation of scattering signals in winter. Scattering signals that appear in late summer are explained by the presence of superimposed ice. This characterization will benefit from future advances in SMRT development, as well as the improved observations of future satellite missions.
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Steensen, B. M., Marelle, L., Hodnebrog, O., & Myhre, G. (2022). Future urban heat island influence on precipitation. Climate Dynamics, .
Abstract: Urbanization and global warming are two of the major human impacts on the environment. The Urban Heat Island (UHI) effect can change precipitation patterns. Global warming also leads to changes in precipitation and especially an increase in intensity and frequency of extreme precipitation. With urbanization expected to grow in the future, the role of UHI in a warmer climate is an important research question. We present results from 20-year long regional convection-permitting model simulations that include the UHI effect, run for historical and future climates for two megacities, Paris and Shanghai. In the warmer future climate, urban-induced precipitation is found to decrease compared to the historical climate, for both mean and extreme precipitation, with large uncertainties due to natural variability. The mean precipitation increase due to UHI in Paris is 2.2 +/- 1.4% and 1.8 +/- 1.3% for historical and future conditions, respectively. Shanghai has slightly weaker mean precipitation change than Paris at present and no change in the future. The future reduction of the urban effect is found to be caused by a decrease in summer precipitation for both cities. Interannual variability in precipitation due to UHI is larger for Shanghai than Paris. The UHI effect on extreme precipitation is also reduced in the future climate and the area with precipitation increase is more concentrated. The general increase in extreme precipitation due to global warming, in combination with the precipitation redistribution due to UHI, underline the importance for future urban planning to mitigate damage caused by extreme precipitation events.
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Stokes, C., Abram, N., Bentley, M., Edwards, T., England, M., Foppert, A., et al. (2022). Response Of The East Antarctic Ice Sheet To Past And Future Climate Change. Nature, 6086(79227), 275–+.
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Strom, J., Svensson, J., Honkanen, H., Asmi, E., Dkhar, N. B., Tayal, S., et al. (2022). Snow Albedo And Its Sensitivity To Changes In Deposited Light-Absorbing particles estimated from ambient temperature and snow depth observations at a high-altitude site in the Himalaya. Elementa-Science Of The Anthropocene, 101(1).
Abstract: Snow darkening by deposited light-absorbing particles (LAP) accelerates snowmelt and shifts the snow meltout date (MOD). Here, we present a simple approach to estimate the snow albedo variability due to LAP deposition and test this method with data for 2 seasons (February-May 2016 and December 2016-June 2017) at a high-altitude valley site in the Central Himalayas, India. We derive a parameterization for the snow albedo that only depends on the daily observations of average ambient temperature and change in snow depth, as well as an assumed average concentration of LAP in snow precipitation. Linear regression between observed and parameterized albedo for the base case assuming an equivalent elemental carbon concentration [ECeq] of 100 ng g(-1) in snow precipitation yields a slope of 0.75 and a Pearson correlation coefficient r(2) of 0.76. However, comparing the integrated amount of shortwave radiation absorbed during the winter season using observed albedo versus base case albedo resulted in rather small differences of 11% and 4% at the end of Seasons 1 and 2, respectively. The enhanced energy absorbed due to LAP at the end of the 2 seasons for the base case scenario (assuming an [ECeq] of 100 ng g(-1) in snow precipitation) was 40% and 36% compared to pristine snow. A numerical evaluation with different assumed [ECeq] in snow precipitation suggests that the relative sensitivity of snow albedo to changes in [ECeq] remains rather constant for the 2 seasons. Doubling [ECeq] augments the absorption by less than 20%, highlighting that the impact on a MOD is small even for a doubling of average LAP in snow precipitation.
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Sulca, J., Takahashi, K., Tacza, J., Espinoza, J., & Dong, B. (2022). Decadal Variability In The Austral Summer Precipitation Over The Central Andes: Observations And The Empirical-Statistical Downscaling Model. International Journal Of Climatology, .
Abstract: The Decadal Variability In Summer Precipitation Over The Central Andes (10 Degrees-30 Degrees S) Is Investigated From 1921 To 2010 Using Low-Pass Filtered Time Series Of The Central And Eastern El Nino-Southern Oscillation (Enso) Pacific (C And E) Indices, The South Pacific Convergence Zone (Spcz) Index, The Atlantic Sst Indices, Atlantic Multidecadal Oscillation (Amo) Index, North Atlantic Oscillation (Nao) Index, And Era-20C Reanalysis. Additionally, An Empirical-Statistical Downscaling (Esd) Model Was Built. A Rotated Empirical Orthogonal Function (Reof) Analysis Shows That The First Leading Mode Of Precipitation (Rpc1) Represents 38.2% Of The Total Decadal Variance. Rpc2, Rcp3, And Rpc4 Represent 18.8, 12.8, And 9.7% Of The Total Decadal Variance, Respectively. Furthermore, Rpc1 Features Highest Loadings Over Most Of The Region. Rpc2 Features A Dipole Of Highest Loadings Over The Southernmost Bolivian Altiplano And Lowest Loadings Over The Northwestern Argentinian Andes. Conversely, Rpc3 Presents Highest Loadings Over The Eastern-Central Bolivian Altiplano And Northwestern Argentinian Andes. Rpc4 Features Highest Loadings Over The Southern Bolivian Andes. Rpc1 And Rpc3 Wet Summers Are Associated With Moisture Transport From The Amazon Basin, But Rpc1 Features The Strengthening Upper-Level Bolivian High-Nordeste Low System Over South America. Conversely, Rpc2 And Rpc4 Wet Summers Are Associated With Local Processes Induced By Southward Displacement Of The South Atlantic Convergence Zone And Warm Sea Surface Temperature (Sst) Anomalies Over The Indian Ocean, Respectively. According To The Esd Model, The Decadal Variability In The Central And Eastern Pacific (Cp And Ep) And Atlantic Ocean Reproduces The Decadal Component Of The Djf Precipitation Over Most Of The Central Andes.
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Swanson, W., Holmes, C., Simpson, W., Confer, K., Marelle, L., Thomas, J., et al. (2022). Comparison Of Model And Ground Observations Finds Snowpack And Blowing Snow Aerosols Both Contribute To Arctic Tropospheric Reactive Bromine. Atmospheric Chemistry And Physics, 222(222), 14467–14488.
Abstract: Reactive Halogens Play A Prominent Role In The Atmospheric Chemistry Of The Arctic During Springtime. Field Measurements And Modeling Studies Suggest That Halogens Are Emitted Into The Atmosphere From Snowpack And Reactions On Wind-Blown Snow-Sourced Aerosols. The Relative Importance Of Snowpack And Blowing Snow Sources Is Still Debated, Both At Local Scales And Regionally Throughout The Arctic. To Understand The Implications Of These Halogen Sources On A Pan-Arctic Scale, We Simulate Arctic Reactive Bromine Chemistry In The Atmospheric Chemical Transport Model Geos-Chem. Two Mechanisms Are Included: (1) A Blowing Snow Sea Salt Aerosol Formation Mechanism And (2) A Snowpack Mechanism Assuming Uniform Molecular Bromine Production From All Snow Surfaces. We Compare Simulations Including Neither Mechanism, Each Mechanism Individually, And Both Mechanisms To Examine Conditions Where One Process May Dominate Or The Mechanisms May Interact. We Compare The Models Using These Mechanisms To Observations Of Bromine Monoxide (Bro) Derived From Multiple-Axis Differential Optical Absorption Spectroscopy (Max-Doas) Instruments On O-Buoy Platforms On The Sea Ice And At A Coastal Site In Utqiagvik, Alaska, During Spring 2015. Model Estimations Of Hourly And Monthly Average Bro Are Improved By Assuming A Constant Yield Of 0.1 % Molecular Bromine From All Snowpack Surfaces On Ozone Deposition. The Blowing Snow Aerosol Mechanism Increases Modeled Bro By Providing More Bromide-Rich Aerosol Surface Area For Reactive Bromine Recycling. The Snowpack Mechanism Led To Increased Model Bro Across The Arctic Ocean With Maximum Production In Coastal Regions, Whereas The Blowing Snow Aerosol Mechanism Increases Bro In Specific Areas Due To High Surface Wind Speeds. Our Uniform Snowpack Source Has A Greater Impact On Bro Mixing Ratios Than The Blowing Snow Source. Model Results Best Replicate Several Features Of Bro Observations During Spring 2015 When Using Both Mechanisms In Conjunction, Adding Evidence That These Mechanisms Are Both Active During The Arctic Spring. Extending Our Transport Model Throughout The Entire Year Leads To Predictions Of Enhanced Fall Bro That Are Not Supported By Observations.
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Thera, B., Dominutti, P., Colomb, A., Michoud, V., Doussin, J. F., Beekmann, M., et al. (2022). O-3-Noy Photochemistry In Boundary Layer Polluted Plumes: Insights From the MEGAPOLI (Paris), ChArMEx/SAFMED (North West Mediterranean) and DACCIWA (southern West Africa) aircraft campaigns. Environmental Science-Atmospheres, 2(4), 659–686.
Abstract: The ozone-NOy photochemistry is explored in contrasting polluted plumes sampled with the Safire ATR 42 research aircraft during three summer field international campaigns in the megacity Paris, the North West Mediterranean basin (WMB) and southern West Africa (SWA). Various metrics derived from the photostationary steady state (PSS) and the ozone production efficiency (OPE) are calculated from airborne observations. A new metric, the oxidant production rate normalized to carbon monoxide (PROx), is introduced and quantified as a function of the processing time of the plume. In most of the polluted plumes, it is found that the Leighton ratio (phi) characterizing the equilibrium between O-3 and NOx is, on average, within the PSS range ([1 +/- 0.32]) or greater. The positive dependence of O-x to NO usually indicates a VOC-sensitive regime inside the plumes with some exceptions. In Paris, under oceanic westerly winds, and during DACCIWA, the plumes show a rural-like chemistry behaviour at moderate NOx levels (NOx-sensitive). Intense and frequent rapid changes in J(NO2), NO and NO2 explain the deviations from the PSS. The OPE for Paris plume suggests that the VOC-sensitive regime extends far beyond the urban plume. The mean ozone production is higher downwind of Paris (30 ppb h(-1) on average) compared to SWA (20 ppb h(-1)) and WMB (6 ppb h(-1)). PROx values vary between 0 (no oxidant production) and 0.27 ppb([Ox]) ppb([CO])(-1) h(-1). The determined uncertainty on the Leighton ratio value could affect the differences in the estimation of the photochemical oxidant production by PO3 and PROx. The emissions of CO along the flight path and the presence of vegetation and high humidity levels might shape the oxidant production depending on the explored environment. While limited in number, PROx values set a benchmark for future photochemical studies to compare with: Paris as representative of an anthropogenic urban plume and WMB as representative of a biogenic continental plume.
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Tilinina, N., Ivonin, D., Gavrikov, A., Sharmar, V., Gulev, S., Suslov, A., et al. (2022). Wind Waves In The North Atlantic From Ship Navigational Radar: Seavision Development And Its Validation With The Spotter Wave Buoy And Wavewatch Iii. Earth System Science Data, 141(8), 3615–3633.
Abstract: Wind Waves Play An Important Role In The Climate System, Modulating The Energy Exchange Between The Ocean And The Atmosphere And Effecting Ocean Mixing. However, Existing Ship-Based Observational Networks Of Wind Waves Are Still Sparse, Limiting Therefore The Possibilities Of Validating Satellite Missions And Model Simulations. In This Paper We Present Data Collected On Three Research Cruises In The North Atlantic And Arctic In 2020 And 2021 And The Seavision System For Measuring Wind Wave Characteristics Over The Open Ocean With A Standard Marine Navigation X-Band Radar. Simultaneously With The Seavision Wind Wave Characteristic Measurements, We Also Collected Data From The Spotter Wave Buoy At The Same Locations, And We Ran The Wavewatch Iii Model In A Very High-Resolution Configuration Over The Observational Domain Seavision Measurements Were Validated Against Co-Located Spotter Wave Buoy Data And Intercompared With The Output Of Wavewatch Iii Simulations. Observations Of The Wind Waves With The Navigation X-Band Radar Were Found To Be In Good Agreement With Buoy Data And Model Simulations With The Best Match For The Wave Propagation Directions. Supporting Datasets Consist Of Significant Wave Heights, Wave Directions, Wave Periods And Wave Energy Frequency Spectra Derived From Both Seavision And The Spotter Buoy. All Supporting Data Are Available Through The Pangaea Repository – Https://Doi.Org/10.1594/Pangaea.939620 (Gavrikov Et Al., 2021). The Dataset Can Be Further Used For Validation Of Satellite Missions And Regional Wave Model Experiments. Our Study Shows The Potential Of Ship Navigation X-Band Radars (When Assembled With Seavision Or Similar Systems) For The Development Of A New Near-Global Observational Network Providing A Much Larger Number Of Wind Wave Observations Compared To E.G. Voluntary Observing Ship (Vos) Data And Research Vessel Campaigns.
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Tu, T., Tweed, S., Dan, N., Descloitres, M., Quang, K., Nemery, J., et al. (2022). Localized Recharge Processes In The Ne Mekong Delta And Implications For Groundwater Quality. Science Of The Total Environment, 8458.
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Uchida, T., Deremble, B., & Popinet, S. (2022). Deterministic Model Of The Eddy Dynamics For A Midlatitude Ocean Model. Journal Of Physical Oceanography, 525(6), 1133–1154.
Abstract: Mesoscale Eddies, Although Being On Scales Of O(20-100) Km, Have A Disproportionate Role In Shaping The Mean Stratification, Which Varies On The Scale Of O(1000) Km. With The Increase In Computational Power, We Are Now Able To Partially Resolve The Eddies In Basin-Scale And Global Ocean Simulations, A Model Resolution Often Referred To As Mesoscale Permitting. It Is Well Known, However, That Due To Gridscale Numerical Viscosity, Mesoscale-Permitting Simulations Have Less Energetic Eddies And Consequently Weaker Eddy Feedback Onto The Mean Flow. In This Study, We Run A Quasigeostrophic Model At Mesoscale-Resolving Resolution In A Double Gyre Configuration And Formulate A Deterministic Closure For The Eddy Rectification Term Of Potential Vorticity (Pv), Namely, The Eddy Pv Flux Divergence. Our Closure Successfully Reproduces The Spatial Patterns And Magnitude Of Eddy Kinetic And Potential Energy Diagnosed From The Mesoscale-Resolving Model. One Novel Point About Our Approach Is That We Account For Nonlocal Eddy Feedbacks Onto The Mean Flow By Solving The “Subgrid” Eddy Pv Equation Prognostically In Addition To The Mean Pv.
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Uchida, T., Jamet, Q., Dewar, W. K., Le Sommer, J., Penduff, T., & Balwada, D. (2022). Diagnosing The Thickness-Weighted Averaged Eddy-Mean Flow Interaction From an Eddying North Atlantic Ensemble: The Eliassen-Palm Flux. Journal Of Advances In Modeling Earth Systems, 141(5).
Abstract: The thickness-weighted average (TWA) framework, which treats the residual-mean flow as the prognostic variable, provides a clear theoretical formulation of the eddy feedback onto the residual-mean flow. The averaging operator involved in the TWA framework, although in theory being an ensemble mean, in practice has often been approximated by a temporal mean. Here, we analyze an ensemble of North Atlantic simulations at mesoscale-permitting resolution (1/12 degrees). We therefore recognize means and eddies in terms of ensemble means and fluctuations about those means. The ensemble dimension being orthogonal to the temporal and spatial dimensions negates the necessity for an arbitrary temporal or spatial scale in defining the eddies. Eddy-mean flow feedbacks are encapsulated in the Eliassen-Palm (E-P) flux tensor and its convergence indicates that eddy momentum fluxes dominate in the separated Gulf Stream. The eddies can be interpreted to contribute to the zonal meandering of the Gulf Stream and a northward migration of it in the meridional direction. Downstream of the separated Gulf Stream in the North Atlantic Current region, the interfacial form stress convergence becomes leading order in the E-P flux convergence.
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Uchida, T., Jamet, Q., Dewar, W. K., Le Sommer, J., Penduff, T., & Balwada, D. (2022). Diagnosing The Thickness-Weighted Averaged Eddy-Mean Flow Interaction From an Eddying North Atlantic Ensemble: The Eliassen-Palm Flux. Journal Of Advances In Modeling Earth Systems, 141(5).
Abstract: The thickness-weighted average (TWA) framework, which treats the residual-mean flow as the prognostic variable, provides a clear theoretical formulation of the eddy feedback onto the residual-mean flow. The averaging operator involved in the TWA framework, although in theory being an ensemble mean, in practice has often been approximated by a temporal mean. Here, we analyze an ensemble of North Atlantic simulations at mesoscale-permitting resolution (1/12 degrees). We therefore recognize means and eddies in terms of ensemble means and fluctuations about those means. The ensemble dimension being orthogonal to the temporal and spatial dimensions negates the necessity for an arbitrary temporal or spatial scale in defining the eddies. Eddy-mean flow feedbacks are encapsulated in the Eliassen-Palm (E-P) flux tensor and its convergence indicates that eddy momentum fluxes dominate in the separated Gulf Stream. The eddies can be interpreted to contribute to the zonal meandering of the Gulf Stream and a northward migration of it in the meridional direction. Downstream of the separated Gulf Stream in the North Atlantic Current region, the interfacial form stress convergence becomes leading order in the E-P flux convergence.
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Uchida, T., Jamet, Q., Poje, A., & Dewar, W. K. (2022). An Ensemble-Based Eddy and Spectral Analysis, With Application to the Gulf Stream. Journal Of Advances In Modeling Earth Systems, 141(4).
Abstract: The “eddying” ocean, recognized for several decades, has been the focus of much observational and theoretical research. We here describe a generalization for the analysis of eddy energy, based on the use of ensembles, that addresses two key related issues: the definition of an “eddy” and the general computation of energy spectra. An ensemble identifies eddies as the unpredictable component of the flow, and permits the scale decomposition of their energy in inhomogeneous and non-stationary settings. We present two distinct, but equally valid, spectral estimates: one is similar to classical Fourier spectra, the other reminiscent of classical empirical orthogonal function analysis. Both satisfy Parseval's equality and thus can be interpreted as length-scale dependent energy decompositions. The issue of “tapering” or “windowing” of the data, used in traditional approaches, is also discussed. We apply the analyses to a mesoscale “resolving” (1/12 degrees) ensemble of the separated North Atlantic Gulf Stream. Our results reveal highly anisotropic spectra in the Gulf Stream and zones of both agreement and disagreement with theoretically expected spectral shapes. In general, we find spectral slopes that fall off faster than the steepest slope expected from quasi-geostrophic theory.
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Uchida, T., Le Sommer, J., Stern, C., Abernathey, R., Holdgraf, C., Albert, A., et al. (2022). Cloud-Based Framework For Inter-Comparing Submesoscale-Permitting Realistic Ocean Models. Geoscientific Model Development, 151(141), 5829–5856.
Abstract: With The Increase In Computational Power, Ocean Models With Kilometer-Scale Resolution Have Emerged Over The Last Decade. These Models Have Been Used For Quantifying The Energetic Exchanges Between Spatial Scales, Informing The Design Of Eddy Parametrizations, And Preparing Observing Networks. The Increase In Resolution, However, Has Drastically Increased The Size Of Model Outputs, Making It Difficult To Transfer And Analyze The Data. It Remains, Nonetheless, Of Primary Importance To Assess More Systematically The Realism Of These Models. Here, We Showcase A Cloud-Based Analysis Framework Proposed By The Pangeo Project That Aims To Tackle Such Distribution And Analysis Challenges. We Analyze The Output Of Eight Submesoscale-Permitting Simulations, All On The Cloud, For A Crossover Region Of The Upcoming Surface Water And Ocean Topography (Swot) Altimeter Mission Near The Gulf Stream Separation. The Cloud-Based Analysis Framework (I) Minimizes The Cost Of Duplicating And Storing Ghost Copies Of Data And (Ii) Allows For Seamless Sharing Of Analysis Results Amongst Collaborators. We Describe The Framework And Provide Example Analyses (E.G., Sea-Surface Height Variability, Submesoscale Vertical Buoyancy Fluxes, And Comparison To Predictions From The Mixed-Layer Instability Parametrization). Basin- To Global-Scale, Submesoscale-Permitting Models Are Still At Their Early Stage Of Development; Their Cost And Carbon Footprints Are Also Rather Large. It Would, Therefore, Benefit The Community To Document The Different Model Configurations For Future Best Practices. We Also Argue That An Emphasis On Data Analysis Strategies Would Be Crucial For Improving The Models Themselves.
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Vandecrux, B., Box, J. E., Wehrle, A., Kokhanovsky, A. A., Picard, G., Niwano, M., et al. (2022). The Determination of the Snow Optical Grain Diameter and Snowmelt Area on the Greenland Ice Sheet Using Spaceborne Optical Observations. Remote Sensing, 141(4).
Abstract: The optical diameter of the surface snow grains impacts the amount of energy absorbed by the surface and therefore the onset and magnitude of surface melt. Snow grains respond to surface heating through grain metamorphism and growth. During melt, liquid water between the grains markedly increases the optical grain size, as wet snow grain clusters are optically equivalent to large grains. We present daily surface snow grain optical diameters (d(opt)) retrieved from the Greenland ice sheet at 1 km resolution for 2017-2019 using observations from Ocean and Land Colour Instrument (OLCI) onboard Sentinel-3A. The retrieved d(opt) are evaluated against 3 years of in situ measurements in Northeast Greenland. We show that higher d(opt) are indicative of surface melt as calculated from meteorological measurements at four PROMICE automatic weather stations. We deduce a threshold value of 0.64 mm in d(opt) allowing categorization of the days either as melting or nonmelting. We apply this simple melt detection technique in Northeast Greenland and compare the derived melting areas with the conventional passive microwave MEaSUREs melt flag for June 2019. The two flags show generally consistent evolution of the melt extent although we highlight areas where large grain diameters are strong indicators of melt but are missed by the MEaSUREs melt flag. While spatial resolution of the optical grain diameter-based melt flag is higher than passive microwave, it is hampered by clouds. Our retrieval remains suitable to study melt at a local to regional scales and could be in the future combined with passive microwave melt flags for increased coverage.
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Verfaillie, D., Pelletier, C., Goosse, H., Jourdain, N. C., Bull, C. Y. S., Dalaiden, Q., et al. (2022). The Circum-Antarctic Ice-Shelves Respond To A More Positive Southern Annular Mode with regionally varied melting. Communications Earth & Environment, 3(1).
Abstract: The Southern Hemisphere cryosphere has recently shown regionally-contrasted responses to climate change, in particular to the positive phases of the Southern Annular Mode. However, the understanding of the impacts of this mode on ice-shelf basal melt at a circum-Antarctic scale is still limited. Here, we performed idealized experiments with a pan-Antarctic regional ice-shelf cavity-resolving ocean-sea-ice model for different phases of the Southern Annular Mode. We show that positive phases lead to increased upwelling and subsurface ocean temperature and salinity close to ice shelves, while the opposite occurs for negative phases. A one-standard-deviation increase of the Southern Annular Mode leads to a net basal mass loss of 40 Gt yr(-1), with strong regional contrasts: increased ice-shelf basal melt in the Bellingshausen and Western Pacific sectors and the opposite response in the Amundsen sector. Estimates of 1000-1200 and 2090-2100 ice-shelf basal melt changes due to the Southern Annular Mode are -86.6 Gt yr(-1) and 55.0 to 164.9 Gt yr(-1), respectively, compared to the present. Positive phases of the Southern Annular Mode lead to enhanced basal melt overall in the Antarctic ice shelves, with strong losses in the Bellingshausen and Western Pacific sectors and gains in the Amundsen Sea, according to ice-ocean model experiments.
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Verin, G., Domine, F., Babin, M., Picard, G., & Arnaud, L. (2022). Metamorphism Of Snow On Arctic Sea Ice During The Melt Season: Impact On Spectral Albedo And Radiative Fluxes Through Snow. Cryosphere, 161(9), 3431–3449.
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Vincent, C., Gilbert, A., Walpersdorf, A., Gimbert, F., Gagliardini, O., Jourdain, B., et al. (2022). Evidence Of Seasonal Uplift In The Argentiere Glacier (Mont Blanc Area, France). Journal Of Geophysical Research-Earth Surface, 1271(7).
Abstract: The hydromechanical processes by which basal water controls sliding at the glacier bed are poorly known, despite glacier basal motion being responsible for a large part of ice flux in temperate alpine glaciers. Previous studies suggest that sliding strongly relates to the quantity of water being stored at the ice-bedrock interface. However, this water storage is difficult to quantify accurately on the basis of surface-motion observations, given that uplift can also be affected by changes in vertical-strain rates and sliding velocity change. Here, we use a comprehensive data set of in situ measurements performed over 2 years on the Argentiere Glacier in the French Alps to investigate the relationships between horizontal and vertical velocities, basal sliding, subglacial runoff and bed separation. We observe strikingly large uplifts varying spatially between 0.20 and 0.90 m over the winter/spring seasons between January and June and with a consistent spatial pattern from 1 year to another. We show, based on observations and three dimensional ice-flow modeling, that these large uplifts cannot be explained solely by changes in strain rates or in sliding up an inclined bed. Our results reveal that more than 80% of the observed uplift is related to enhanced bed separation through cavitation, allowing us to estimate the volume occupied by water-filled subglacial cavities. Our interpretation of uplift being mainly caused by increased cavitation is also consistent with an associated increase in the observed surface horizontal velocity. These findings provide important observational constraints for testing subglacial hydrological models.
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Viviroli, D., Sikorska-Senoner, A., Evin, G., Staudinger, M., Kauzlaric, M., Chardon, J., et al. (2022). Comprehensive Space-Time Hydrometeorological Simulations For Estimating Very Rare Floods At Multiple Sites In A Large River Basin. Natural Hazards And Earth System Sciences, 222(9), 2891–2920.
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Voglimacci-Stephanopoli, J., Wendleder, A., Lantuit, H., Langlois, A., Stettner, S., Schmitt, A., et al. (2022). Potential Of X-Band Polarimetric Synthetic Aperture Radar Co-Polar Phase difference for arctic snow depth estimation. Cryosphere, 161(6).
Abstract: Changes in snowpack associated with climatic warming has drastic impacts on surface energy balance in the cryosphere. Yet, traditional monitoring techniques, such as punctual measurements in the field, do not cover the full snowpack spatial and temporal variability, which hampers efforts to upscale measurements to the global scale. This variability is one of the primary constraints in model development. In terms of spatial resolution, active microwaves (synthetic aperture radar – SAR) can address the issue and outperform methods based on passive microwaves. Thus, high-spatial-resolution monitoring of snow depth (SD) would allow for better parameterization of local processes that drive the spatial variability of snow. The overall objective of this study is to evaluate the potential of the TerraSAR-X (TSX) SAR sensor and the wave co-polar phase difference (CPD) method for characterizing snow cover at high spatial resolution. Consequently, we first (1) investigate SD and depth hoar fraction (DHF) variability between different vegetation classes in the Ice Creek catchment (Qikiqtaruk/Herschel Island, Yukon, Canada) using in situ measurements collected over the course of a field campaign in 2019; (2) evaluate linkages between snow characteristics and CPD distribution over the 2019 dataset; and (3) determine CPD seasonality considering meteorological data over the 2015-2019 period. SD could be extracted using the CPD when certain conditions are met. A high incidence angle (>30 circle) with a high topographic wetness index (TWI) (>7.0) showed correlation between SD and CPD (R2 up to 0.72). Further, future work should address a threshold of sensitivity to TWI and incidence angle to map snow depth in such environments and assess the potential of using interpolation tools to fill in gaps in SD information on drier vegetation types.
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Wever, N., Keenan, E., Amory, C., Lehning, M., Sigmund, A., Huwald, H., et al. (2022). Observations And Simulations Of New Snow Density In The Drifting Snow-Dominated Environment Of Antarctica. Journal Of Glaciology, .
Abstract: Owing To Drifting Snow Processes, Snow Accumulation And Surface Density In Polar Environments Are Variable In Space And Time. We Present New Field Data Of Manual Measurements, Repeat Terrestrial Laser Scanning And Snow Micro-Penetrometry From Dronning Maud Land, Antarctica, Showing The Density Of New Snow Accumulations. We Combine These Data With Published Drifting Snow Mass Flux Observations, To Evaluate The Performance Of The 1-D, Detailed, Physics-Based Snow Cover Model Snowpack In Representing Drifting Snow And Surface Density. For Two Sites In East Antarctica With Multiple Years Of Data, We Found A Coefficient Of Determination For The Simulated Drifting Snow Of R(2) = 0.42 And R(2) = 0.50, Respectively. The Field Observations Show The Existence Of Low-Density Snow Accumulations During Low Wind Conditions. Successive High Wind Speed Events Generally Erode These Low-Density Layers While Producing Spatially Variable Erosion/Deposition Patterns With Typical Length Scales Of A Few Metres. We Found That A Model Setup That Is Able To Represent Low-Density Snow Accumulating During Low Wind Speed Conditions, As Well As Subsequent Snow Erosion And Redeposition At Higher Densities During Drifting Snow Events Was Mostly Able To Describe The Observed Temporal Variability Of Surface Density In The Field.
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Wilhelm, B., Amann, B., Corella, J. P., Rapuc, W., Giguet-Covex, C., Merz, B., et al. (2022). Reconstructing Paleoflood Occurrence and Magnitude from Lake Sediments. Quaternary, 5(1).
Abstract: Lake sediments are a valuable archive to document past flood occurrence and magnitude, and their evolution over centuries to millennia. This information has the potential to greatly improve current flood design and risk assessment approaches, which are hampered by the shortness and scarcity of gauge records. For this reason, paleoflood hydrology from lake sediments received fast-growing attention over the last decade. This allowed an extensive development of experience and methodologies and, thereby, the reconstruction of paleoflood series with increasingly higher accuracy. In this review, we provide up-to-date knowledge on flood sedimentary processes and systems, as well as on state-of-the-art methods for reconstructing and interpreting paleoflood records. We also discuss possible perspectives in the field of paleoflood hydrology from lake sediments by highlighting the remaining challenges. This review intends to guide the research interest in documenting past floods from lake sediments. In particular, we offer here guidance supported by the literature in how: to choose the most appropriate lake in a given region, to find the best suited sedimentary environments to take the cores, to identify flood deposits in the sedimentary sequence, to distinguish them from other instantaneous deposits, and finally, to rigorously interpret the flood chronicle thus produced.
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Wilhelm, B., Rapuc, W., Amann, B., Anselmetti, F. S., Arnaud, F., Blanchet, J., et al. (2022). Impact of warmer climate periods on flood hazard in the European Alps. Nature Geoscience, 151(2), 118–+.
Abstract: Flooding is a pervasive natural hazard-costly in both human and economic terms-and climate change will probably exacerbate risks around the world. Mountainous areas, such as the densely populated European Alps, are of particular concern as topography and atmospheric conditions can result in large and sudden floods. In addition, the Alps are experiencing a high warming rate, which is probably leading to more heavy rainfall events. Here, we compile palaeoflood records to test the still uncertain impact these climatic trends might have on flood frequency and magnitude in the European Alps. We demonstrate that a warming of 0.5-1.2 degrees C, whether naturally or anthropogenically forced, led to a 25-50% decrease in the frequency of large (>= 10 yr return period) floods. This decreasing trend is not conclusive in records covering less than 200 years but persistent in those ranging from 200 to 9,000 years. By contrast, extreme (>100 yr) floods may increase with a similar degree of warming in certain small alpine catchments impacted by local intensification of extreme rainfall. Our results show how long, continuous palaeoflood records can be used to disentangle complex climate-flooding relationships and assist in improving risk assessment and management at a regional scale. Moderate flooding in the European Alps declined during past warmer periods, whereas extreme floods both increased and decreased, according to an analysis of palaeoflood records.
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