我国南方地区的中尺度对流复合体

MESLSCALE CONVECTIVE COMPLEXES OVER THE SOUTHERN CHINA MAINLAND

根据日本ＧＭＳ资料和部分常规资料，对我国南方地区春末夏初的１０个中尺度对流复合体（ＭＣＣＳ）做了分析。它们的基本特征与美国ＭＣＣ相近，它们主要活动在夜间，一般在山地背风一侧斜坡上或坡底附近形成；并在对流层中低层中低纬度地区几个天气系统的迭加处获得发展；向东们南方向移动，与７００～５００ｈＰａ之间的平均气流方向大体一致，冷云罩面积约为１．４×１０￣５ｋｍ￣２，比美洲的（２～３×１０￣５ｋｍ￣２）略小；持续时间为１２小时左右，比美洲的（１０小时）稍长。云区形状呈椭圆形，但伤心率≥０．６．云顶最低温度一般在一８６℃以下，出现在冷云罩面积达到最大之前４～６小时。

Ten mesoscale convective complexes(MCCs ) over the southern China mainlandduring late spring and early summer were computed and analysed using GMS S-VISSRdata and conventional data.The results show that they are nocturnal and initiate atslope or near slope bottom of plateau or mountains leeward , and develop at the specialfavorable area where several synoptic systems from low-and midlatitude are merging orinteracting with each other.They move toward east by south and tend to the mean flowin 700～500hPa layer.The coldcloud-shield is about 1.4 × 10￣5km￣2, which is smallerthan that of MCC in the America (2～3× 10￣5km￣2),but it lasts for about 12 hours whilethe American shield about 10 h0urs. The eccentricity of cloud shape(≥0.6) is slightlysmaller than that in the America(≥0.7).The minimum temperature of cloud top isgenerally colder than一86℃,which appears 4～6hours earlier than the time of themaximum coldDcloudDshield extent.