南海暖水季节和年际变化的初步研究

南海暖水具有明显的季节和年际变化。利用气候平均的COADS资料和NCEP大气资料分析了南海暖水的季节变化及其与海面净热通量的关系,以及由此引起的南海地区大气环流的变化。发现海面净热通量在南海暖水的季节变化过程中起到了主要的作用;冬季无暖水存在时,最大上升气流位于赤道及以南地区的印尼群岛附近,夏季最大上升气流北移到了南海暖水上空,南海暖水上空对流强烈,成为大气的对流活动中心。利用50年逐月的SODA海温资料进行垂直方向的3次样条插值,定义并计算南海暖水的强度指数,分析南海暖水的年际变化,并对南海暖水的几个异常暖年份作了合成分析,探讨了暖水年际变化的形成因素。

A Preliminary Study of the Seasonal and Interannual Variations of the South China Sea Warm Water

The South China Sea(SCS) warm water has a large seasonal cycle and interannual fluctuations.This paper analyzes the annual variability of the SCS warm water and its relation with the net heat flux as well as atmospheric circulation associated with the warm water,using COADS and NCEP datasets.The analysis suggests that the net heat flux is the most important factor in the annual cycle of the warm water;the largest upward motion region of the atmosphere is located south of the equator and Indonesia in winter(There is no warm water in the SCS),and it moves northward to the SCS region in summer(The SCS warm water is strongest).The SCS warm water becomes a convective center of the atmosphere in summer.This paper defines the volume index of the SCS warm water using monthly SODA datasets with a cubic spline interpolation method.And the interannual variations are analyzed.By analyzing the several interannual warm events of the SCS warm water,the mechanism of abnormal warm of the SCS warm water is discussed.