利用NCEP/NCAR再分析资料、NOAA的OLR资料及CMAP降水资料,研究了1979--2008年历年4—5月南亚高压在中南半岛上空建立过程的特征,发现有21年存在西部中心生成加强与东部中心减弱消亡共同进行的过程,称为南亚高压的重建过程。南亚高压重建过程存在明显的年际差异,根据重建开始时间可分为重建正常年、偏早年及偏晚年。重建正常年,重建之前,对流活动中心在中南半岛南面的海洋大陆一带,到重建阶段,对流伸向中南半岛。南亚高压重建偏早年,对流推进至中南半岛上空的时间偏早;而重建偏晚年则刚好相反。说明南亚高压重建过程与中南半岛上空的对流活动有密切关系。南亚高压重建时,中南半岛的对流活动带来充沛的降水,释放出大量的凝结潜热。已有研究表明在由冬向夏的演变过程中,南亚高压表现出“趋热性”,因此,对流降水释放的凝结潜热可能是南亚高压在中南半岛上空重建的原因。
Using pentad-based NCEP/NCAR reanalysis, OLR and CMAP precipitation dataset, the features of South Asia High (SAH) reconstruction process during April and May from 1979 to 2008 are investigated. We found that the SAH reconstruction is a 21-year process which characterizes the strengthening of SAWs western center located in Indochina Peninsula and decaying of SAH's eastern center in western Pacific east of the Philippines. Based on the significant interannual variability involved, normal years, early years and late years of reconstruction are selected according to their starting date. In normal years, active convection is located between 10 °S and 10°N before the reconstruction process; during the reconstruction stage, active convection extends from maritime continents to the peninsula. In early(late) years, strong convection expanding to the peninsula is earlier(later), indicating that there exists close connection between typical SAH reconstruction's starting date and developing date of strong convection in the peninsula. The starting date of a rain belt and a diabatic heating center that enter the SAH reconstruction. Thus, latent heating resulting SAH's reconstruction in the peninsula. SAH's westem center are consistent with the process of from convective precipitation is a possible reason for SAH's reconstruction in the peninsula.