摘要
基于1998年11月28日至12月27日的调查航次的CTD资料,采用P矢量方法对调查期间南海环流进行了诊断计算,也对比了在此期间TOPEX/ERS卫星高度计SSH的资料,得到了1998年冬季南海上层环流的以下一些重要特征.(1)南海中部环流系统主要特征:在冬季越南近岸出现西边界南向射流.这支沿岸南向射流以东、114°E以西存在一个尺度大的、显著气旋式环流,它位于南自10°N左右北至16°N附近区域.在区域东中部存在一个尺度不大的、较弱的反气旋暖涡.该反气旋涡中心约位于14°N附近.在上述强的气旋式环流涡与较弱的反气旋式环流涡之间,存在一支强的、逆风方向的,即偏东北方向的海流.上述是冬季南海中部基本流态,并与200m处水平温度分布与密度分布有很好的对应.产生上述基本流态的动力原因有两个:1)在偏东北季风作用下,与地形变化相互作用,是本文首次提出的,并指出,其动力原因与冬季黄海暖流形成机制有相似之处;2)由于斜压场与地形的联合效应(JEBAT).(2)在海区南部存在一个反气旋式环流,在加里曼丹岛西北还有一个尺度不大、冷的气旋式涡.(3)南海北部环流系统:1)在吕宋岛西北明显地存在一个气旋环流系统,并有3个冷水中心;2)在此气旋式环流系统的一个冷水中心(约19°30′N,119°30′E)以西,存在一个反气旋式涡;3)
On the basis of hydrographic data obtained in November 28-December 27, 1998 cruise, diagnostic calculation of the circulation in the South China Sea (SCS) is made by using the P vector method, in combination with SSH data from TOPEX/ERS-2 analysis. The following results have been obtained. (1) The main characteristics of the circulation systems in the central SCS are as follows. A coastal southward jet in winter is present at the western boundary near the coast of Vietnam. There is a strong cyclonic circulation with a large horizontal scale east of this coastal southward jet and west of 114°E, and it is located about in the region from 10°N to 16°N. There is a weaker anticyclonic and warm eddy with a not large horizontal scale, and its center is located about at 14° N. There is a strong and northeastward flow opposing the northeasterly monsoon between a strong cyclonic circulation and a weaker anticyclonic circulation above. The above distribution of circulation is the basic pattern of circulation in the central SCS, which agrees qualitatively with the horizontal distribution of temperature at 200 m level. The dynamical mechanism which causes the above basic pattern of circulation is duto the following two points: 1) the interaction between the wind stress and topographic change under the strong northeasterly monsoon. The above dynamical cause is firstly explaied, and it is pointed out further that its dynamical cause is similar to that which causes the Huanghai Warm Current to flow northward; and 2) joint effect of the baroclinity and bottom topographic (JEBAT). (2) In the southern SCS there is an anticyclonic circulation, and also there is a smaller scale cold water and cyclonic eddy. (3) The circulation systems in the northern SCS are as follows. 1) There is a cyclonic circulation system northwest of Luzon, and it has three centers of the cold water;2) there are an anticyclonic eddy west of a center of the cold water about at 19° 30′N,119° 30′E, which is one of three centers of the cold water in the above cyclonic circulation system;3) there is a warm and anticyclonic circulation south of Hainan Island; 4) there are a northeastward flow, the South China Sea Warm Current, in winter off Guangdong coast in the northern SCS, which was pointed firstly out by Guan. (4) Comparing the hydrographic structure and distribution of stream functions with the SSH data from TOPEX/ERS-2 analysis in the SCS during December 1998, they agree qualitatively.
出处
《海洋学报》
CAS
CSCD
北大核心
2004年第2期1-10,共10页
基金
国家基础研究发展规划项目(G1999043805).
关键词
南海
环流
气旋
数值模拟
SCS upper-layer circulation in the winter of 1998
seasonal feature of circulation system
strong flow opposing the northeasterly monsoon in winter
SSH data from TOPEX/ERS-2 .
