摘要
利用１９９８年“南海季风实验（ＳＣＳＭＥＸ）”南北部两个点的资料，采用１． Ｌａｕｎｉａｎｅｎ和Ｔ．Ｖｉｈｍａ提出的方法，计算了潜热通量、感热通量和风应力，分析了南海上 混合层动力、热力特征及其与南海夏季风爆发之间的关系。发现在西南季风爆发前后，南海 北部、南部的两个观测点的海洋上混合层温度和深度随时间的变化具有不同的特点：北部混 合层温度经历由高到低再变高，混合层深度经历由浅变深再变浅的３个时段；南部混合层温 度经历由低到高再变低，混合层深度经历由深变浅再变深的３个时段。这与南海南、北部海 面的风和海面热通量具备不同的特征有关。在５～６月南海上混合层动力、热力特征基本受 局地风与短波辐射控制，海面潜热和感热的作用较小。在５月份，南海南部观测点海面附近 存在浅薄的高盐高密度层，在６０ｍ以上的上层海洋内存在着许多高盐高密度核。在１９９８年 “南海季风实验”期间南海南、北部两个观测点都存在较浅薄的障碍层，在西南季风爆发期 间，南海北部观测点的障碍层较厚达到 ２０ ｍ以上。
In this paper, using the observation data at two points (south point and north point) during South China Sea Monsoon Experiment (SCSMEX), the heat flux and wind stress are calculated by the method of J. Launianen and T. Vihma, and the relation between the dynamic and thermodynamic features of upper mixed layer and the summer monsoon onset. It is found that, before and after the 1998 summer monsoon onset, there are different variations features of temperature and depth of the mixed layer in north and south of the SCS. The variations in temperature and depth of the mixed layer could be divided into three sub-periods: Before the onset of the southwest monsoon, in the north observation point (20°N, 116°E), there is higher mixed layer temperature (28°C or more) and shallower mixed layer depth (about 10 m); during the onset of the southwest monsoon, the wind is strong, the sun radiation is weak, the temperature of the mixed layer is low (28°C or less), and the depth of the mixed layer increases to 20 m; after the onset of the southwest monsoon, the depth of the mixed layer decreases to 10 m, and the temperature reverses to the value of 28'C or more. Besides, the depth of the mixed layer in the south observation point (6°15＇N, 110°E) is twice as deep as in the north point of the SCS. Its average value is 27.3 m, the temperature of the mixed layer is 29°C or more all the time; before the onset of the southwest monsoon, the temperature of the mixed layer is low (29°or so), and the depth increases gradually by the forcing of stronger northeaster or northwester; during the onset period of the southwest monsoon, the temperature of the mixed layer increases to reach 31°C, and the depth of the mixed layer reduces to 10 m or less, after the onset of the southwest monsoon, the depth of the mixed layer increases to 40 m, the temperature reduces to 30°C. Above features are controlled dominantly by wind and sun radiation in sea surface, and the effects of latent heat and sense heat flux are very smaller than wind and sun radiation. In May, there are shallower layer with high salinity and high density and many nuclear with high salinity and high density in the south of SCS. During SCSMEX of 1998, there are shallower barrier layers in the south and north and the thickness barriers layer is thicker above 20 m in north of SCS at southwest monsoon onset.
出处
《气候与环境研究》
CSCD
2000年第4期469-481,共13页
Climatic and Environmental Research
基金
国家科技部攀登项目A"南海季风试验研究"
国家重点科技项目!97-926-05-02共同资助
