Simulated Southern Ocean Upwelling at the Last Glacial Maximum and Early Deglaciation: The Role of Eddy‐Induced Overturning Circulation

Abstract

AbstractWe explore the changes in Southern Ocean upwelling patterns during the last glacial maximum (LGM) and early deglaciation using a fully coupled climate model with ocean eddies parameterized via the Gent‐McWilliams scheme. Relative to the preindustrial climate, the model simulates an equatorward shift of the upwelling of the residual circulation in the Southern Ocean during the LGM, which is consistent with paleo‐evidence of export production. This change in upwelling primarily arose from an altered eddy‐induced meridional overturning circulation (MOC) that resulted from the expanded sea ice and enhanced buoyancy loss around Antarctica during the LGM, which modulated the slope of buoyancy surface in the Southern Ocean. We have also found that there was a poleward shift of the upwelling of the residual circulation in the Southern Ocean during the early deglaciation, which was different than the change in the wind‐driven upwelling and primarily driven by variations in the eddy‐induced MOC.