Reduced Warm Bias in the Surface Southern Ocean by Improved Parameterization of Wind‐Driven Vertical Mixing in an Eddy‐Resolving Coupled Global Climate Model

Abstract The sea surface temperature (SST) in the Southern Ocean (SO) exerts widespread effects on the climate. Yet there is a persistent warm SST bias in the SO across generations of coupled global climate models (CGCMs). Existing literature blames such bias primarily on the deficiencies of model‐simulated atmospheric processes or basin‐scale ocean circulations. In this study, we show that the warm SST bias in the SO can be mitigated by parameterizing the vertical mixing induced by wind‐driven near‐inertial internal waves (NIWs) in the thermocline. By representing NIW‐induced vertical mixing in the thermocline of an eddy‐resolving CGCM, the warm SST bias in the SO is significantly reduced due to the enhanced downward heat flux from the surface boundary layer to the ocean interior. Our findings provide a new pathway to alleviate the warm SST bias in the SO, helping in improving the fidelity of model projected future climate changes.