| Summary: | Changes in Southern Ocean physics are dynamically linked to westerly winds, ocean currents, and the distribution of Antarctic sea ice in the Southern Hemisphere. As a result, it is critical to comprehend the response of Southern Ocean physics to the distribution of Antarctic sea ice on a basin scale. This modeling study employs a fully coupled Earth system model to investigate the effect of Antarctic Sea ice distribution on Southern Ocean dynamics during the past 20,000 years. The findings show that the formation and melting of sea ice have an effect on the distribution of surface buoyancy flux over the Southern Ocean. The simulated sea ice edge (grid points in the ice model have a sea ice concentration above 5%) in the Southern Ocean almost demarcates the borderline between the lower and upper meridional overturning cells. The seemingly permanent Antarctic sea ice edge (grid points in the ice model with a sea ice concentration greater than 80%) coincides with the shift of buoyancy flux from positive (buoyancy gain) to negative (buoyancy loss). Furthermore, the negative surface buoyancy flux zone has shifted polewards for the past 20,000 years, with the exception of approximately 14.1 thousand years. Our findings show that Antarctic sea ice feedback affects the surface buoyancy flux, affecting the overturning circulation in the Southern Ocean.
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