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Thursday, April 15 2021
11:00am - 12:00pm
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Dr. Alex Robel

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Bottom-Up Control of Subpolar Gyres and the Southern Ocean Overturning Circulation

The School of Earth and Atmospheric Sciences presents Dr. Earle Wilson, CalTech

Bottom-Up Control of Subpolar Gyres and the Southern Ocean Overturning Circulation

The subpolar gyres of the Southern Ocean establish an important dynamical link between the Antarctic Circumpolar Current (ACC) and the coastline of Antarctica.  Despite their key involvement in the production and export of bottom water and the poleward transport of oceanic heat, these gyres are rarely acknowledged in conceptual models of the Southern Ocean circulation, which tend to focus on the zonally-averaged overturning that occurs across the ACC.

Here, we re-examine this framework by carrying out a series of process-based idealized simulations that isolate the effect of a subpolar gyre on the Southern Ocean circulation. This isolation was accomplished by using different topographic configurations that approximate the bathymetry of the Ross and Weddell Sea basins to varying extents. A key result is that the zonal ridges that exist along the northern boundaries of these gyres play a critical role in setting the stratification and circulation across their respective regions.

The impact of these zonal ridges extend far beyond their local vicinity and substantially modifies both the regional overturning and the mechanisms by which heat is transported to the Antarctic margin. These findings demonstrate that subpolar gyres are fundamental features of the Southern Ocean and underscore the need to integrate their impact into our theoretical framework of the regional circulation.

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