Interactions among the winter monsoon, ocean eddy and ocean thermal front in the South China Sea

Abstract

Sea surface temperature (SST) in boreal winter shows a robust feature of ocean front west of Luzon Island where a cyclonic ocean eddy is associated with the winter northeast monsoon. Our analyses further show that cold (warm) water is located in the northwest (southeast) part of the Luzon eddy due to ocean advection, forming the west Luzon front. The results suggest a novel mechanism of the positive feedback among the winter monsoon, ocean eddy and ocean front over the South China Sea. A strong positive wind stress curl associated with the winter monsoon and mountainous islands produces the Luzon eddy. With eddy heat advection, the Luzon eddy is accompanied by negative (positive) SST anomalies in the northwest (southwest) part of the eddy, inducing the west Luzon thermal front. The SST anomalies can further force an anomalous wind pattern that converges onto the positive SST anomalies and diverges from the negative SST anomalies. The anomalous wind distribution in turn enhances the positive wind stress curl west of Luzon Island.