The Ice-Ocean Governor: ice-ocean stress feedback limits Beaufort Gyre spin up
Atmospheric and Oceanic Sciences Departmental Seminar Series
presents
The Ice-Ocean Governor: ice-ocean stress feedback limits Beaufort Gyre spin up
a talk by
Gianluca Meneghello
Research Scientist, Department of Earth, Atmospheric and Planetary Sciences,
MIT
Abstract
The Beaufort Gyre is a key circulation system of the Arctic Ocean and its main reservoir of freshwater. Freshwater storage and release affects Arctic sea ice cover, as well as North Atlantic and global climate. The dynamics of the gyre is governed by a combination of two mechanisms: eddy fluxes, and the Ice-Ocean Governor, a negative feedback between the surface currents and the ice speed. 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. The governor sets the basic properties of the gyre, such as its depth, freshwater content, and strength.
We will look at the ice-ocean governor from the theoretical, numerical and the observational point of view. Using observational evidence, we will compare the relative role of eddy fluxes and the governor in equilibrating the gyre in the current climate. As the Arctic warms in the future, reduced sea ice extent and more mobile ice will result in a deeper and faster Beaufort Gyre, and the accumulated freshwater will be released by Ekman upwelling or enhanced baroclinic instability.