2000年8月南海中部与南部海洋温、盐与环流特征

HYDROGRAPHIC AND CIRCULATION CHARACTERISTICS IN MIDDLE AND SOUTHERN SOUTH CHINA SEA IN SUMMER,2000

根据 2 0 0 0年 8— 9月份南海中部与南部航次的温、盐资料 ,采用P 矢量诊断方法 ,结合ADCP测流资料和同期伪风应力资料以及TOPEX/Poseidon高度计资料 ,研究了 2 0 0 0年夏季风持续强迫之后南海大尺度环流与中尺度涡旋的空间结构。结果表明 ,南海夏季温度和盐度水平分布随深度有显著的变化 :中层 (2 5 0— 4 0 0m左右 )温、盐水平分布与其它各层的温度和盐度分布相比有很大的差异。用诊断方法计算得到的环流场与用TOPEX/Poseidon海面高度计资料计算得到的地转流场比较一致 ,即流场内部有多个中尺度的涡旋 ,主要有越南东南外海反气旋涡、中沙群岛东南反气旋涡以及南沙群岛东北角的气旋涡等 ,这说明南海中部与南部盛夏环流具有较强的地转分量和显著的多涡结构 ,并且这些中尺度涡在垂向上存在速度场的切变。

This paper analyzed hydrological data in the South China Sea (SCS) collected in marine investigation cruises during mid-summer 2000. Data from in-situ observations showed remarkable thermohaline characteristics that varied with depth. In the intermediate layer. High salinity and high temperature were observed,while at the other lower and upper layers salinity and temperature were found to compensate each other. In order to calculate the circulations in different levels. P-vector method was applied to the observed temperature and salinity. The results calculated based on sea surface height coincided with those obtained from the TOPEX/Poseidon satellite. During the survey period in the southern SCS,a cyclonic circulatory pattern presented at the lower layer,while an anti-cyclonic circulatory pattern showed in the upper layer. In detail,a multi-eddy structure was found comprising of several meso-scale eddies including anti-cyclonic eddies off the Vietnam coast,near Zhongsha islands and in the NE part of Nansha islands. Vertical sheer of velocity occurs in these eddies,especially those off the coast of Vietnam,which are typical examples of baroclinic eddies. The circulation and eddy patterns well reflected the geostrophic effort in the areas.