914 / 2024-09-19 20:03:59

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

Parameterization,Vertical Heat Transport,Turbulent Thermal Wind Balance

The vertical buoyancy flux (B_f) 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 B_f^TTW 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-simulated turbulent vertical viscosity, horizontal density gradient and a scaling relationship to adjust for the 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 surface mixed layer in coarse-resolution simulations.