海陆分布和地形对1998年夏季风爆发的热力影响

THERMAL INFLUENCES OF LAND-SEA CONTRAST AND TOPOGRAPHY ON SUMMER MONSOON OF 1998

利用“南海季风科学试验”（SCSMEX）所获得的可靠资料，对1998年区域海陆热力状况进行了分析与对比，并着重讨论了西太平洋和青藏高原地区热力作用对1998年季风爆发及发展的可能影响。结果发现：大气热源分布与海陆分布有密切联系，由于地形的阻挡使得在包含有南北海陆分布差异的地区，热源主要大值带较全海洋区域明显偏南。表面加热存在明显的季节变化和海陆差异。西太平洋地区与夏季风爆发之间的联系主要表现在海温和潜热加热的变化上。高原在亚洲夏季风爆发过程中的作用机制不同：在南海季风爆发期间以感热加热为主，印度季风爆发期间以水汽凝结释放潜热为主。

In this work, the SCSMEX data are used to diagnose and compare the local land-sea thermal conditions and to discuss the possible influences of the thermal forcing of the western Pacific and the Tibetan Plateau on the onset and the development of summer monsoon in 1998. Results show that the distributions of the heat sources are closely related to the land-sea contrast. The topographic blocking leads to the main maximum zones of the heat sources more southward in the areas with the land-sea contrast than in the areas with only oceans. The surface heating is characterized with the apparent seasonal variation and the land-sea difference. The relationship between the western Pacific and the onset of summer monsoon appears in the variations of the surface sea temperature (SST) and the latent heat. The mechanism of the influence of the Tibetan Plateau during the summer monsoon is different: it is characterized by the sensible heating during the South China Sea monsoon and by the condensed latent heating during the Indian monsoon.