南海深水区季平均海流的诊断计算

根据南海温、盐度历史观测数据的季平均值和季平均风应力场,采用三维非线性海流诊断模式,对南海大陆架外深水海区四季平均流场进行了数值模拟计算。所得的南海四季环流总趋势以及一些中小尺度的涡旋现象,同已有的一些研究结果基本相符。此外,还较好地反映了南海海流的季节变化特征和流场在不同深度的分布特点。

DIAGNOSTIC CALCULATIONS FOR THE SEASONAL-AVERAGED CURRENT FIELD IN THE DEEP WATER ZONE OF THE SOUTH CHINA SEA

Based on the seasonal-averaged observational data of water temperature and salinity and seasonal-averaged wind stress, numerical simulations are made for the seasonal-averaged current field with a .3-D nonlinear diagnostic model over the deep water zone,with a depth greater than 200m, of the South China Sea (SCS).The results show that the general patterns of the circulations in the four seasons agree to those of the previous studies. In addition, the seasonal variations of the current field are significant and there exist many small-to meso-scale eddies, among which a cyclonic cold eddy at the west of Jinlan Bay of Vietnam and an anticyclonic warm eddy at the area between Xisha and Zhongsha Islands are quite stable. The patterns at 500m depth level agree in general to those at the surface level with the difference mainly in winter and summer reflects the variations in the strength of wind drift.The branching of Kuroshio into the SCS is most significant in winter. In spring and autumn, the Kuroshio also goes in through southern Bass Strait but, in the form of "flow envelope", goes out through the northern strait,with a small amount of water entering the northern SCS. In summer,it enters through middle Bass Strait then returns towards northeast through the strait, with no apparent branching into the internal of the SCS. At 500m depth level, Kuroshio branches into the SCS through the southern Bass Strait and then, in the form of "flow envelope", goes out through the northern strait in spring, autumn and winter. In summer, the pattern at 500m depth level is same as that at the surface level.