基于卫星观测的南海和东亚夏季风指数初探

A PRIMARY STUDY OF SUMMER MONSOON INDEX OVER THE SOUTH CHINA SEA AND EAST ASIA BASED ON SATELLITE OBSERVATION

运用1980-2002年5-8月GMS TBB候平均资料,经过统计分析得到：南海和东亚候夏季风活动指数定义为候平均TBB≤273K；其强度分为3级,即弱季风为268 K＜TBB≤273 K,一般季风为263 K＜TBB≤268 K,强季风为TBB≤263 K。与此同时,还给出了运用TBB候距平帮助判识季风强度的分析方法。运用该季风指数,统计分析了上述各年季风初始爆发日期和各年各月季风活动情况。另外,还对比分析了1998年长江中下游地区暴雨和1994年华南暴雨2个典型暴雨灾害年季风活动,展示了候季风活动与暴雨期间各暴雨过程之间的密切关系。

The results by statistical analysis of Black-body Temperature （TBB） pentad mean from the Japanese GMS in the period of May to August, 1980-2002, show that the summer monsoon index （SMI） is defined to be the pentad mean TBB〈273 K. Its intensity includes three classifications： TBB〉268 K for weak monsoon, 268 K〉TBB〉263 K for normal monsoon and TBB〈263K for strong monsoon over the south China sea and East Asia. In the meantime, a diagnostic method using TBB pentad anomaly is also introduced to help identify monsoon intensity. The SMI is used to run statistical analyses of the initial onset of the monsoon and its pentad variations with years and months. The fairly closely relationship is presented between pentad monsoon activity and heavy rainfall periods embedded in the two typical disastrous years of 1994 and 1998 resulted from heavy rainfall over Yangze River basin and south China.