南海上层水温分布的季节特征

THE SEASONAL FEATURES OF TEMPERATURE DISTRIBUTIONS IN THE UPPER LAYER OF THE SOUTH CHINA SEA

为对南海上层水温分布特征有一总体认识，利用气候平均的1°×1°网格的Levitus资料，分析了南海0－200m层共10个等深面上的季平均温度分布状况。结果表明，南海上层水温分布的季节变化明显，季风和太阳辐射对水温分布有显著影响，四季平均水温分布与平均环流状况对应较好。冬、春两季在吕宋岛西北海域有一冷涡（即吕宋冷涡），夏、秋季在越南沿岸出现另一冷涡（即越南冷涡）。这两个冷涡均对应着本海区尺度较小的气旋式环流和正的风应力旋度。吕宋冷涡还与黑潮在吕宋海峡的形变有关，越南冷涡则与局地强上升流有联系。

In order to obtain the genetal features of temperature distributions in the upper layer (UL) of the South China Sea, the climatological Levitus data with horizontal resolution of 1°×1°lat. / lon. grid were used to analyze the seasonal averaged temperature distributions on ten isobathic levels (0-200m). The results showed that the temperature distributions in the UL varied remarkably with seasons and were influenced significantly by the monsoon and solar radiation. The water temperature averaged in the UL of the whole sea area was the lowest in winter and highest in summer. The patterns of temperature distributions coincided to a great extent with the seasonal mean circulation. The temperature field structure above 200m depth suggested that the deformation of the Kuroshio in the Luzon Strait helps to form the high temperature water tongue in the northeast of the SCS in winter. In spring and summer and autumn, the temperature front in the Luzon Strait can affect the westward extending of the deformation of the Kurshio. A cold eddy called Luzon cold eddy (LCE) appears in the northwest sea region between 16°and 19°N off Luzon Island in winter and spring. A weak cold water area appears in the southwest of the Dongsha Islands in summer and in the east of the Zhongsha Islands in autumn. It may be formed by the seasonal variation of the LCE's position and intensity. In summer and autumn another cold eddy with very low temperature called Vietnam cold eddy (VCE) appears between 12° and 16°N along the coast of Vietnam. The VCE's intensity would decline and its central position would move slightly southward from summer to autumn. As to the dynamic mechanism of the formation of the LCE and VCE, they allcorrespond to a meso-scale close cyclonic circulation and positive wind stress curl. The LCE is also related to the deformation of the Kuroshio in the Luzon Strait, and the VCE is probably connected with the local strong upwelling along the coast of Vietnam.