摘要
分析近年欧洲中心５月份逐日格点风资料，发现南海季风建立在５月中旬，其流场特征为赤道西风带向东北伸展，并汇入华南沿海的横向切变线内。其建立过程与一次涡旋活动有关。利用等熵坐标质量连续方程计算的非绝热加热率分布表明，加热对高层辐散有直接的影响，从而有利于低层涡旋的维持。另一方面，涡旋内水汽辐合，大量潜热释放，从而使我国西南—中南半岛地区成为亚洲最大的加热中心。与此同期，热带洋面上出现非绝热冷却，促成了闭合经向季风环流的建立。这种质量循环，保证了南海季风的稳定。在特定的气候、地理条件下，非绝热加热（冷却）是促成南海季风建立的重要机制。
Having analyzed the ECMWF wind data of recent years, this paper found that the establishment of Summer monsoon over the South China Sea occurs around the middle of May, which is characterized by northeastward stretching of the equatorial westerly belt and forming of an east-west-oriented flow shear along the coast of South China. And this seasonal variation is associated with a vortex process.The distributions of diabatic heating rate estimated from integration of the isentropic mass continuity equation show that heating influences the upper-level divergence directly and the low-level vortex subsequently. On the other hand, water vapour convergence in the vortex causes release of latent heat, making the southwestern China-IndoChina Peninsula areas to be the strongest center of heating. Meanwhile, diabatic cooling occurs over the tropical ocean. As a result, a closed meridional monsoon circulation is formed, which is necessary to keep the summer monsoon steady in the lower layer.Thus, diabatic heating (cooling ) is the key mechanism of stimulating the establishment of summer monsoon over the South China Sea under the specific climatic and geographic circumstances.
出处
《热带海洋》
CSCD
1994年第4期17-24,共8页
基金
国家自然科学基金
关键词
赤道西风带
南海
夏季风
非绝热加热
季风环流
equatorial westerly, summer monsoon over the South China Sea, diabatic heating rate, latent heat, meridional monsoon circulation
