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Origin of Circumpolar Deep Water intruding onto the Amundsen and Bellingshausen Sea continental shelves

Séminaire de Yoshihiro Nakayama (Jet Propulsion Laboratory, California Institute of Technology, CA, USA), Mardi 28 Aout à 13h salle Lliboutry, Bât. Glaciologie

27 août 2018, par Fabien Gillet-Chaulet

Origin of Circumpolar Deep Water intruding onto the Amundsen and Bellingshausen Sea continental shelves.
By Yoshihiro Nakayama (Jet Propulsion Laboratory, California Institute of Technology, CA, USA)

Abstract : Melting of West Antarctic ice shelves is enhanced by Circumpolar Deep Water (CDW) intruding onto the Amundsen and Bellingshausen Seas (ABS) continental shelves. Despite existing studies of cross-shelf and on-shelf CDW transports, CDW pathways onto the ABS originating from further offshore have never been investigated. Here, we investigate CDW pathways onto the ABS using a regional ocean model. Simulated CDW tracers from a zonal section across 67ºS (S04P) circulate along the Antarctic Circumpolar Current (ACC) and Ross Gyre (RG) and travel into ABS continental shelf after 3-5 years but source locations are shifted westward by 900 km along S04P in 2001-2006 compared to 2009-2014. We find that simulated on- and off-shelf CDW is 0.1-0.2 ºC warmer in the 2009-2014 case than in the 2001-2006 case together with changes in simulated ocean circulation. These differences are primarily caused by lateral, rather than surface, boundary conditions, implying that large-scale atmospheric and ocean circulations are able to control CDW pathways and thus off- and on-shelf CDW properties.

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