南海上层环流季节变化的诊断计算

Diagnostic calculation of seasonal varieties of upper-layer circulation in South China Sea

通过一个全球的二维诊断模型,采用Levitus温盐资料和COADS风应力资料,并结合动力计算来研究南海上层环流的季节变化。计算结果与其它模式结果和观测结果非常相似。南海北部(南部)全年存在一气旋式(反气旋式)环流。在冬季气旋式环流几乎占据了整个南海,夏季则以反气旋式环流为主。泰国湾的环流在冬季(夏季)是气旋式的(反气旋的)。南海的西边界流有明显的季节变化,其在冬季从卡里马塔海峡流出南海,夏季部分西边界流从台湾海峡流出南海。越南离岸流在春季就开始出现,其位置比夏季的越南离岸流的位置偏北。

A 2-dimensional global diagnostic model, which is based on Takano Ocean Model （TOM） and combined with dynamic calculation, is used to investigate the seasonal varieties of the upper-layer circulation in the South China Sea. The model is driven by Levitus （2001） climatological data of temperature/salinity fields and COADS surface wind stress data, respectively. The simulated results agree well with the results of other model and observation. A large cyclonic gyre （anti-cyclonic gyre） persists throughout the year in the northern part （southern part） of the South China Sea. The circulation in the Gulf of Thailand is anti-cyclonic in summer and cyclonic in winter. The western boundary current in the South China Sea has distinct seasonal varieties. In winter, the western boundary current mainly contains southward and south- westward flows, and outflows from the South China Sea through the Karimata Strait. In summer, the western boundary current mainly contains northward and northeastward flows, and outflows from the South China Sea through the Taiwan Strait. The Vietnam Offshore Current begins to appear in spring.