横穿黑潮锋断面的流场结构

CURRENT STRUCTURE ALONG CROSS-KUROSHIO FRONT SECTION IN THE EAST CHINA SEA

基于一组简化了的运动方程组，在充分考虑底Ekman层作用的情况下，提出一种横穿锋面的断面上流场结构的计算方法。应用该方法对东海横穿黑潮锋的不同断面上的流场（1989－1990年资料）进行计算。结果表明，黑潮锋左侧（向岸侧）存在较强的上升流，而锋区右侧（离岸侧）表现为海水的下降运动。垂直流速为（1－20）×10－3cm／s的量级，而横穿锋面方向的水平流速为1－3cm／s，其中以夏、秋季跃层附近最强。在陆架坡折处，上升流转向陆架。同时，还分析了正压场和斜压场对这种流场的不同贡献，认为在黑潮区，正压场起主要作用;而在内陆架区，斜压场则变得重要。将计算的流场与硝酸盐的分布比较表明，两者有较好的对应关系。

The method for calculating the cross-frontal sectional current presented in this paper is based on the simplified equations of motion and considers fully the effect of the bottom Ekman layer. The current is calculated for several cross-Kuroshio front sections from 1989 to 1990 in the East China Sea, with the current field being divided into barotropic and baroclinic components. The results show that strong up-welling occurs on the left (shoreward) side of the Kuroshio front and downwelling on its right (seaward) side, that the vertical velocity is (1-20)×10-3 cm/s, and that the cross-frontal current velocity is 1-3 cm/s, and maximizes near the therm-ocline in summer and fall. The upwelling water turns to the inner continental shelf near the continental shelf break. lt is suggested that tlie effect of the barotropicifield dominates in the Kuroshio area while that of the baroclinic field becomes important in the inner continental shelf. The cross-frontal exchange is caused mainly by the baroclinic instability. There is a good correlation between the calculated current and the nutrient salt distribution.