The Effect Of Ocean Dynamics On The South China Sea Surface Temperature

Sea surface temperature (SST) is a key factor of the interactions between the ocean and atmosphere in the South China Sea (SCS). Because very little is known about the effect of ocean dynamics, we expect the role of ocean dynamics in determining the SCS SST variability on the basis of former studies. Taking advantage of a suite of new satellite observations and some historical datasets, we have investigated the spatial distribution of SST and its interannual variations in the SCS. The SCS Cold Tongue (SCT) and Luzon Warm Ridge (LWR) are founded over the SCS during the boreal winter. The formation and decay mechanisms of the SCT and LWR in winter are proposed. Focusing on the SST variability for feedback on the atmosphere, the relationship between the warm water and the SCS summer monsoon (SCSSM) are investigated. Some main and new research results are listed as follows:(1) The SCT is a conspicuous gap of the Indo-Pacific warm water pool in boreal winter. Annual range of SCT (LWR) is larger (smaller) than that of the same latitudinal region. Min SST appears in winter and the time of Max SST is May in the most of deep basin. 30℃warm water is located west of the Philippines.(2) The formation mechanisms for the climatology and interannual variability of SCS SST in boreal winter are investigated. The winter SCS is divided into two parts by the axis of the maximum northeasterly monsoonal winds. The positive wind curl in the southeastern half of the ocean drives a cyclonic gyre circulation in the deep basin. As its western boundary current, an intense southward flow is found south of Vietnam on the continental slope separating the Sunda Shelf to the west and the deep SCS basin to the east. This slope current exceeds 0.5 m/s in speed and advects cold water from the north. This cold advection results in a distinct SCT in the winter SST climatology. Both the slope current and SCT are strongest in November to February.