89 / 2023-07-29 10:47:29

A Scale-aware Parameterization of Restratification Effect of Turbulent Thermal Wind Ba

parameterization,turbulent thermal wind balance,Surface boundary layer

The vertical buoyancy flux under the turbulent thermal wind (TTW) balance B_f^TTW plays an important role in restratifying the surface mixed layer in winter. So far most of the global ocean models are too coarse to resolve this process. In this paper, a scale-aware parameterization is proposed for the B_f^TTW under the TTW balance and implemented in a hierarchy of regional ocean simulations over the winter Kuroshio extension with horizontal resolutions ranging from 27 km to 1 km. The parameterization depends on the Coriolis parameter, model-resolved vertical turbulent viscosity, horizontal density gradient and a scaling relationship to adjust for effects of model horizontal resolution on the simulated horizontal density gradient. It shows good skills in reconciling the difference between B_f^TTW in the coarse-resolution simulations (27 km, 9km and 3 km) and in the 1-km simulation where B_f^TTW is well resolved. Furthermore, implementation of the parameterization improves the simulated stratification in the mixed layer in the coarse-resolution simulations.