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

Gianluca Meneghello, John Marshall, Jean-Michel Campin, Edward Doddridge & Mary-Louise Timmermans
Geophysical Research Letters, 2018.
http://doi.org/10.1029/2018GL080171

Abstract

The Arctic Ocean’s Beaufort Gyre is spun up by the prevailing anticyclonic winds forcing sea-ice and ocean motion. A regulator is described that limits spin up and explains the stabilization of the sea-ice covered Beaufort Gyre, even while subject to sustained anticyclonic wind-stress curl. Anticyclonic surface stress due to sea-ice drift drives Ekman downwelling which intensifies the gyre geostrophic flow. The geostrophic flow, in turn, reduces ice-ocean relative speeds and surface stresses: an ice-ocean stress governor. Analytical and numerical modeling is employed to demonstrate the mechanism, contrasting equilibration processes in an ice-covered versus ice-free gyre. Observations are presented and interpreted in terms of the governor mechanism. Our study suggests that continued Arctic sea-ice loss will lead to reduced effectiveness of the governor and change the fundamental internal dynamics of the gyre.

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