东海环流的一个两层模式

A two-layer model for the circulation of the East China Sea

本文用一个两层原始方程数值模式，对东海的环流现象进行了机制性的探讨。从整体上来看，海区的一些主要流态特征彼此密切相关，且在动力上都是比较稳定的。黑潮在台湾东北的入侵主要表现在下层。底斜联合效应（ＪＥＢＡＲ）、惯性效应、摩擦效应都是这支入侵流态的发生机制，而底形与行星β效应则使它表现出向岛强化的特征。下层黑潮入侵后，大部分作反气旋回转，成为台湾暖流（ＴＷＣ）下层的外海分支。ＴＷＣ下层沿岸分支能否形成，则取决于黑潮入流上下流速比γ的大小，以及上层海峡入流是否北上。ＴＷＣ上层流动的形成是海峡水入侵后在β效应作用下的结果，它在温州外海也将分出一支向外海流去。文章指出，台湾东北的冷水块不是“尾涡”所致，而是下层黑潮舌状入侵的具体表征；台湾北部的暖涡则是上层ＴＷＣ北上时与冷水块相互作用的结果。此外，本文对钓鱼岛以北的锋涡与逆流现象也作了一些初步的分析与讨论。

A two-layer numerical model is developed to study the dynamical structures and the formation mechanisms of the shelf circulation and Kuroshio system in the East China Sea (ECS)On the whole, the main features of this region are highly correlated and dynamically stable.The Kuroshio northeast of Taiwan always intrudes onto the shelf. and manifests itself chiefly in the lower layer. The joint effect of baroclinicity and relief (JEBAR), the horizontal advection and bottom friction are the triggering mechanisms for this ageostrophic intrusion current, while the topographic and planetary beta-effects make it intensified towards the northern edge of Taiwan Island. After intruding onto the shelf, most of the lower-layer Kuroshio water turns anticyclonically, forming the outer branch of the lower-layer Taiwan Warm Current (TWC). Whether its inner partner can form depends upon the rate of the upper-to the lower-layer speeds of the Kuroshio inflow, and the northward extending of the upper-layer Strait warm water. The upper-layer TWC results from the Taiwan Strait inflow, and a part of it branches out in the open sea off Wenzhou. In this paper, We also point out that thecold-core water mass northeast of Taiwan is, in fact, the behaviour of the lower-layer intrusive loop, and the interaction between it and the upper-layer TWC leads to the formation of the well-known warm-core gyre. Besides, a preliminary study is also made on the frontaleddy north of Diaoyu Island.