Effects of Wind and Isopycnal Mixing on Southern Ocean Surface Buoyancy Flux and Antarctic Bottom Water Formation

Abstract In coarse resolution ocean models, eddy diffusive effects are parameterized using an isopycnal mixing coefficient, which controls mixing strength along isopycnals. Recent high‐resolution simulations show that increasing the wind stress over the Southern Ocean leads to increased local isopycnal mixing. In this work, we investigate how wind and isopycnal mixing affect surface temperature and salinity in the Southern Ocean and the buoyancy of waters near Antarctica. Using an idealized Massachusetts Institute of Technology general circulation model basin‐channel model, we vary both Southern Ocean wind stress and the isopycnal mixing coefficient independently. We find that when the wind and isopycnal mixing coefficient are small, a strong halocline in the far south prevents AABW formation. Increasing the wind stress and/or isopycnal mixing brings warmer, saltier water to the surface of the Southern Ocean, where it cools, becomes denser, and forms AABW. Increasing the isopycnal mixing coefficient also increases the latitudinal extent of the source waters for AABW formation.