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The Ice-Ocean governor: ice-ocean stress feedback limits Beaufort Gyre spin up

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Thursday, 08 November 2018, 2:00

Thursday, November 8, 2018. 2:00 PM. The Ice-Ocean governor: ice-ocean stress feedback limits Beaufort Gyre spin up. John Marshall, Massachusetts Institute of Technology. Sponsored by NOAA GFDL. More here.

The Beaufort Gyre is a key circulation system of the Arctic Ocean and its main reservoir of freshwater. We describe a mechanism that is fundamental to its dynamics, namely the “ice-ocean stress governor”. Wind blows over the ice and the ice drags the ocean. But as the gyre spins up, currents catch the ice up and turn off the surface stress. This governor sets the basic properties of the gyre, such as its depth, freshwater content, and strength. Analytical and numerical modeling is employed to contrast the equilibration processes in an ice-covered versus ice-free gyre. We argue that as the Arctic warms, reduced sea-ice extent and more mobile ice will result in a deeper and faster Beaufort gyre, accumulating more freshwater which will be released by Ekman upwelling or baroclinic instability. Finally, we describe how the Ice-Ocean governor might play an important role south of the Antarctic Divergence in the seasonal ice zone of the Southern Ocean. 

Location  Smagorinsky Seminar Room, NOAA GFDL, Princeton, NJ