The Responses of Antarctic Sea Ice and Overturning Cells to Meridional Wind Forcing

Abstract

Meridional wind changes over the Antarctic seasonal ice zone have influenced recent sea ice extent variability. Using observations and an eddy-resolving channel model, this study examines how meridional wind anomalies alter sea ice distribution and the underlying ocean. Southerly wind anomalies in winter increase sea ice extent by driving equatorward ice drift, leading to more leads/polynyas, enhanced ice production, and coastal buoyancy loss, while freshening occurs farther offshore. In summer, the same southerly anomalies reduce sea ice extent by warming the sea ice edge through a strengthened meridional overturning circulation (MOC) driven by increased surface heat loss and brine rejection. Water-mass transformation analysis shows increased bottom water formation associated with brine rejection and coastal cooling. Northerly wind anomalies produce opposite responses. Overall, meridional wind anomalies regulate sea ice extent, polynya activity, buoyancy fluxes, MOC strength, and deep water properties.