亚洲夏季风建立前后对流层温度场演变特征及其热力成因

对１９９６年亚洲夏季风爆发前后（３～６月）印度及南海季风区对流层温度演变特征及其热力成因作了比较分析。结果表明：印度和南海夏季风的爆发与各季风区对流层中上层南北温差逆转密切相关，而南北温差逆转是由１０～３０°Ｎ之间纬度带对流层的季节性增暖引起的。夏季风爆发前期，南海季风区的增温主要由暖平流及非绝热加热过程（主要为凝结潜热）共同作用所致。春季在印度季风区大陆上空存在显著的下沉绝热增温，使得对流层中上层的增温率比华南大陆及邻近地区上空的增温率显著得多。但印度季风区冬末春初的南北温差（南暖北冷）也非常明显，以至该地区对流层中上层增暖到引起南北温差发生逆转的时间较迟，而南海季风区对流层中层南北温差发生逆转的时间相对要早，因而印度夏季风比南海夏季风迟爆发。

EVOLUTION OF TEMPERATURE FIELDS IN TROPOSPHERE AND CORRESPONDING THERMAL MECHANISMS DURING THE PREAND POST-ONSET PERIODS OF ASIAN SUMMER MONSOON

The evolutions of the troposphere temperature fields over Indian and South China Sea (SCS) monsoon areas and their thermal mechani sms are comparatively analysed during the period from March to June, 1996. The results show that the onsets of Indian summer monsoon and SCS summer monsoon are closely associated with the seasonal warming in the troposphere over the zonal belt of 10-30°N in the two monsoon areas above, which leads to the inversion of meridional temperature gradient. During the pre-onset period, the warming over the SCS monsoon region is mainly due to the warm horizontal advection and diabatic heating(latent heat) processes, meanwhile the warming is suppressed by the vertical adiabatic process (cooling). In spring over Indian monsoon region, the significant adiabatic heating due to the subidence motion, which compensates the cooling due to the strong cold advection and diabatic cooling processes, results in a larger warming rate than over the SCS monsoon region. However, the meridional temperature gradient over Indian monsoon region is so large during the late winter and early spring that it takes longer time to warm the troposphere to have the reversion of meridional temperature gradient than it does over the SCS monsoon region, which leads to the phenomenon that the SCS summer monsoon outbreaks earlier than the Indian summer monsoon in general.