2008年8月25日上海大暴雨过程分析  

An Analysis on the 25 August 2008 Heavy Rain Process in Shanghai

作　　者：张吉[1,2] 曹晓岗 邹兰军 王慧 陈永林 

机构地区：[1]南京大学大气科学系,南京210093 [2]上海市中心气象台,上海200030

出　　处：《大气科学研究与应用》2009年第2期42-51,共10页Atmospheric Science Research and Application

摘　　要：利用常规观测资料、非常规加密观测资料、FY2C卫星云图及多普勒雷达和风廓线等资料,对2008年8月25日早晨上海市中心城区出现的短时突发性大暴雨过程进行了分析。结果表明:冷暖空气在长江中下游地区交汇诱发了中低层低涡的生成,为强对流天气的生成提供了有利的大尺度环流背景;低涡中生成的3个中尺度对流云团的发生、发展及其东移、合并是造成此次大暴雨的直接原因;台风"鹦鹉"登陆后,残留云系在副高西侧的西南气流引导下与来自东海的东南气流带来的暖湿气流在长江下游地区相遇,提供了大量的水汽来源,为上海有效位能的快速积累和强对流天气的形成提供了有利的环境条件。中高层弱冷空气入侵促进了近地面层的暖湿空气沿冷空气坡面爬升,促使了上海地面中尺度低压和辐合线形成,从而激发了此次强对流天气的发生;从雷达反射率因子图、径向速度图上可以清楚地看到几个风暴的发生、发展;风廓线图上提前0.5～1 h出现的强风速脉动为强对流天气的预警提供了一定的帮助。Based on conventional observations,non-conventional observations,FY2C satellite cloud images, Doppler radar data and wind profile data,an analysis on the meso-scale system which is responsible for a abrupt strong rainstorm in the urban area of Shanghai on 25 August 2008 shows that a vortex is induced by the meeting of cold and warm air in the middle and lower reaches of the Yangtze River.The generation and eastward-moving of 3 meso-scale cloud clusters in the vortex have caused the heavy rain directly. After typhoon Nuri landed in Guangdong Province,the remaining clouds leaded by the warm and moist southwest wind in the west of the Pacific high pressure converge with the water vapor coming from the northwest Pacific Ocean in the lower reaches of the Yangtze River,which helps accumulate the available potential energy and to form suitable conditions for the occurring of the rainstorm.The downward invasion of a weak cold air flow from higher level plays an important role in the formation of the mesoscale low pressure and the convergence line in the surface of Shanghai.It forces the warm and moist air to climb up along the inclined plane and thus to trigger the abrupt emergence of the rainstorm.The forming and moving of several cell storms can be traced in the base reflectivity products and the radar velocity products of Doppler radar.Wind-speed pulsation which occurs in 30 minutes to one hour before the strong convection appears in the wind profile pictures of Doppler radar can provide some help for predicting in advance.

关 键 词：突发性大暴雨 中尺度对流云团 中尺度低压 

分 类 号：P458.121.1[天文地球—大气科学及气象学]