Mesoscale wind stress-SST coupling induced feedback to the ocean in the western coast of South America

Abstract

The feedback induced by mesoscale wind stress-SST coupling to the ocean in the western coast of South America was studied using the Regional Ocean Modeling System (ROMS). To represent the feedback, an empirical mesoscale wind stress perturbation model was constructed from satellite observations, and was incorporated into the ocean model. Comparing two experiments with and without the mesoscale wind stress-SST coupling, it was found that SST in the mesoscale coupling experiment was reduced in the western coast of South America, with the maximum values of 0.5 °C in the Peru Sea and 0.7 °C in the Chile Sea. A mixed layer heat budget analysis indicates that horizontal advection is the main term that explains the reduction in SST. Specifically, the feedback induced by mesoscale wind stress-SST coupling to the ocean can enhance vertical velocity in the nearshore area through the Ekman pumping, which brings subsurface cold water to the sea surface. These results indicate that the feedback due to the mesoscale wind stress-SST coupling to the ocean has the potential for reducing the warm SST bias often seen in the large-scale climate model simulations in this region.