华南“94·6”特大暴雨的中尺度对流系统及其环境场研究 Ⅰ.引发暴雨的β中尺度对流系统的数值模拟研究  

A Study of Mesoscale Convective Systems and Its Environmental Fieldsduring the June 1994 Record Heavy Rainfall of South ChinaPart I: A Numerical Simulation Study of Meso-βConvective System Inducing Heavy Rainfall

作　　者：孙建华[1] 赵思雄[1] 

机构地区：[1]中国科学院大气物理研究所,北京100029

出　　处：《大气科学》2002年第4期541-557,共17页Chinese Journal of Atmospheric Sciences

基　　金：国家重点基础研究发展规划项目G1998040907"我国重大气候;天气灾害形成机理;预测理论的研究"第Ⅱ部分;国家自然科学基金资助项目49735180以及国家科技部攀登专项95-专-3共同资助

摘　　要：选取1994年6月12日～13日的过程,在确定云雨、垂直运动的模拟基本正确的基础上,利用模式输出资料对β中尺度对流系统的结构进行分析研究.结果表明:低层的水汽辐合很强,并且出现在对流发展前2～3h,有利于对流的启动;随着对流系统的发展,最大的垂直运动向上扩展,饱和层和中性层也不断向上伸展,对流层中层的中性层结既是对流发展的结果,也可能是其维持机制之一;强对流系统发展较强时,低层(600hPa以下)是辐合,而中高层为高压辐散气流,高层的辐散气流对对流系统的发展、维持有一定的作用;系统发展最强时垂直方向是两个模态,发展和衰减阶段一般为多个模态;强对流系统发展的环境风场为低层有西南、东南和北风三支气流辐合,而高层以偏北风为主;切变线上对流系统的降雨量有3h左右的周期变化.A case (12 UTC, 12 June~ 12 UTC, 13 June) was selected for a deep study. Due to successful simulations of cloud water and vertical motion, there existed the probability to study the shear lineand the meso-β systems along it by using the model output data. Results show that the convergence of low-level moisture flux, which occurs about 2~3 hours before the strong convective systems, is triggered and very strong. There is obviously strong convergence in Guangxi in the low layer, its cyclonic convergence is caused by three currents from southwest, southeast and north respectively, while in the upper layer its divergence is mainly due to strong northeasterly current. There are two modes in the vertical direction when the meso-β system is the most strong and several modes when the system is developing and decaying. With the development of strong convective systems, the maximum vertical motion extends upwards, so do the saturated layer and neutral layer. The appearance of neutral layer in the middle troposphere is not only the result of convective systems development but also the mechanism of convective systems maintaining, which is greatly different from that of strong rainstorms of North America. There was 3 hours interval variations of the convective systems along the shear line.

关 键 词：暴雨 中尺度对流系统 环境场 数值模拟 

分 类 号：P458.121.1[天文地球—大气科学及气象学]