三维斜压陆架海模式的应用: 南海上混合层的季节变化

The application of a three-dimensional baroclinic shelf sea model: The seasonal variation of the South China Sea upper mixed layer

从一个三维斜压陆架海模式的数值模拟结果来揭示南海上混合层的季节变化规律，结果表明：（１）在南海北部上混合层的厚度（即混合层的下界深度）具有明显的季节性变化，与在南海南部上混合层的变化明显不同，前者的混合强度的变化幅度远比后者的要大得多．（２）在中南半岛中部东岸外海的西边界区域内，由于经常受冷涡控制，下层冷水涌升，上层水体层化显著，使得该海区垂直混合减弱．（３）在一些气旋（反气旋）涡的边缘，混合层厚度等值线分布密集，且水平梯度较大．（４）南海上混合层的厚度分布特征与上层环流的分布格局之间存在着较好的地转调整关系．

According to a three-dimensional baroclinic shelf sea model's numerical simulation results, the seasonal variation of the South China Sea(SCS)upper mixed layer is revealed. It is shown that: (1) In the northern SCS, the variation of the upper mixed layer depth(i. e., the depth of the lower limit of mixed layer) is distinctly seasonal, which is different to that in the southern SCS, and the strength variation range of mixed layer is larger in the northern SCS. (2) In the western boundary area along the east off shore of middle Indo-China Peninsular, due to the control of cold eddy, the lower cold water upwells, and the upper layer water stratifys distinctly, which makes the vertical mixing weakened. (3) In the peripheries of some cyclonic(anticyclonic) eddies, the distribution of mixed layer depth isobath is dense and its horizontal gradient is large. (4) There is a good relation of geostrophic adjustment between the distribution characteristic of upper mixed layer and the pattern of upper circulation in the SCS.