东中国海环流及其季节变化的数值模拟

关于东中国海环流的研究，国内外学者已做了大量的工作。早期科学家们主要依赖于对温盐资料和少数测流资料的分析研究对渤、黄、东海的环流结构有了较系统和深入的认识。东中国海环流是由一个气旋式的“流涡”组成，东侧主要是北上的黑潮-对马暖流-黄海暖流及其延伸部分；西侧为南下的沿岸流系。黑潮对东中国海环流的影响是如此之大，以致于除了某些局部区域外，上述海域主要流系的冬、夏季分布形式比较相似而无本质上的差异(胡敦欣等，1993)。但本文所研究海域正处于世界上最显著的季风区，冬、夏季盛行风向基本相反，过渡季节(春、秋季)风向多变，风力减弱；海洋热盐结构季节变化明显(如冬季混合强，而夏季层化明显等)，这些因素都使得东中国海环流存在着较明显的季节变化。 自20世纪80年代以来，东中国海环流的数值模拟工作逐步展开，并已成为研究环流结构及其形成机制的强有力工具。但由于数值模式本身以及计算方案的缺陷(如有些学者用固定的风场、温盐场对东中国海环流进行诊断模拟等)和观测资料的不足，数值模拟的结果难以得到验证，渤、黄、东海的环流研究中仍有大量的问题存在争议，以待澄清。例如，台湾暖流的来源、流径;对马暖流的来源;夏季黄海暖流的流径以及黄海冷水团环流等均有不同的论述。对黄、东海环流季节变化的数值模拟工作也较少，多用冬、夏典型月份的风场强迫积分至稳定态，给出冬、夏季环流，这种做法值得商榷。三维环流模式很难在1个月内达到稳定态，尤其是夏季层化明显、风力减弱的情况下，非常定风场的影响更应引起人们的重视。 本文采用比较符合实际的计算方案，用年循环风场和海面热通量场为外强迫，对渤、黄、东海的环流及其季节变化进行了模拟，并对一些争议问题进行了探讨。

NUMERICAL SIMULATION OF THE SEASONAL CIRCULATION IN THE HUANGHAI SEA AND EAST CHINA SEA

The Princeton Ocean model was used to simulate the circulation in the Huanghai Sea and East China Sea and its annual cycle showing that: (1)A weak countercurrent exists on the left side of the Kuroshio. The countercurrent separates from the main stream of the Kuroshio around 30°N, 128°E, flows southwestward along isobaths, meets with the offshore branch of the Taiwan Warm Current around 28°N, 124°E, then returns back and joins the main stream, thus forming a cyclonic circulation. (2) The Taiwan Warm Current has an inshore branch and an offshore branch. Only in summer, the inshore branch can reach to about 30°N, where separates into two branches; one flows northward Changjiang River mouth, the other flows eastward, to be one of the sources of the Tsushima Warm Current. (3) The Tsushima Warm Current has multiple-sources. (4) In summer, Huanghai Sea Warm Current does not enter the southern Huanghai Sea. It mainly origins from the middle shelf flow in seasons other than autumn, in summer, it seemingly comes from the extension of the inshore branch of the Taiwan Warm Current. (5) The Eddy in the northern East China Sea exists all year round, with a closing cyclonical circulation in winter and summer. The seasonal variation of the eddy is influenced by the components of the cyclonical circulation, such as the Huanghai Sea Warm Current and middle shelf flow.