Séminaire IGE

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A coupled ice-ocean framework to investigate the impact of sea-ice deformation in the winter sea-ice mass balance in the Arctic

vendredi 6 octobre 2023 - 13h30

Guillaume Boutin - NERSC, Bergen, Norvège
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Sea ice is a key component of the earth’s climate system as it modulates the energy exchanges and associated feedback processes at the air-sea interface in polar regions. These exchanges strongly depend on openings in the sea-ice cover, which are associated with fine-scale sea-ice deformations, but the importance of these processes remains poorly understood as most numerical models struggle to represent these deformations without using very costly horizontal resolutions (~1km). Here, we present results from a 12km resolution ocean--sea-ice coupled model, involving the ocean component of NEMO and the sea ice model neXtSIM. This is the first coupled model that uses a brittle rheology to represent the mechanical behaviour of sea ice. Using this rheology enables the reproduction of the observed characteristics and complexity of fine-scale sea ice deformations with little dependency on the mesh resolution.    We investigate the sea ice mass balance of the model for the period 2000-2018. After a careful evaluation of the modelled sea ice against available observations (extent, drift, volume, deformations, etc.), we assess the relative contribution of dynamical vs. thermodynamic processes to the sea-ice mass balance in the Arctic Basin. We find a good agreement with ice volume changes estimated from the ESA CCI sea-ice thickness dataset in the winter, demonstrating the ability of brittle rheologies to produce a reasonable sea ice mass balance over long periods. Using the unique capability of the model to reproduce sea-ice deformations, we estimate the contribution of leads and polynyas to winter ice production. We find this contribution to add up from 25% to 35% of the total ice growth in pack ice in winter, showing a significant increase over the 18 years covered by the model simulation. This coupled framework opens new opportunities to understand and quantify the interplay between small-scale sea-ice dynamics and ocean properties that cannot be inferred from satellite observations.

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Equipe organisatrice : Organisation labo

Salle de conférence MCP, IGE MCP, 38400 Saint Martin d'Hères

Informations de visio :

Register here : https://univ-grenoble-alpes-fr.zoom.us/meeting/register/tJMvdu2opz8jHd2lTeg8i9W1A1EuJftY4CpJ#/registration