1983年梅雨期前后亚洲季风区水汽输送的分析

A STUDY OF VAPOUR TRANSPORTATION OVER ASIAN MONSOON REGION IN MEI—YU SEASON OF 1983

分析了1983年江淮流域入梅前、梅雨期以及出梅后垂直积分的水汽输送和水汽通量散度分布,计算了南海和中国东部地区的水汽收支。结果指出:江淮流域入梅前,华南地区降水的水汽主要来自印度西南季风和东南季风气流;梅雨期降水的水汽主要来自印度西南季风气流;出梅后华北雨季则主要受中低纬水汽输送气流汇合的影响。分析表明,江淮流域梅雨期是印度西南季风气流加强并东进北上,西太平洋高压东撤所造成的;而梅雨结束则是由于西南季风气流减弱西退和西太平洋高压西进北上所造成的;此外,还讨论了水汽输送、水汽通量辐合与云量及我国东部降水的关系。

The distribution of vertically integrated water vapour transportation and flux divergence inthe Mei-yu season over the Changjiang River and the Huaihe River basins is studied.The watervapor budget over the Nanhai Sea and the eastern China area is calculated.The results indicatethat water vapour associated with precipitation over south China before the Mei-yu period comesmainly from the two air currents which are the Indian southwestern monsoon and the easternAsian southeastern monsoon,respectively;water vapour of precipitation in the Mei-yu periodcomes mainly from the Indian southwestern monsoon current;and after the Mei-yu period,therainy season over North China is mainly affected by the convergence currents from the middleand the low latitude.The analysis shows the Mei-yu period is beginning when the Indian south-western monsoon current strengthens and moves eastward then northward,and the western Pacifichigh shifts eastward:and the Mei-yu period is ending when the southwestern monsoon currentweakens and declines westward,and the western Pacific high stretches westward and moves north-ward.In addition,the relationships between the water vapour flux convergence and cloudiness/precipitation over the eastern China are discussed.