2004年8月23日曲靖市突发性强降水成因浅析

2004年8月23日在曲靖市境内出现了局地大暴雨的罕见强降水天气过程,出现了30年以来最大日雨量。利用micaps常规资料和GOES-9卫星云图对这次暴雨过程进行分析,结果表明,高空副热带高压变化和低空切变线共同影响是造成这次强降水的主要原因。来自副热带高压外围的西南气流为暴雨输送了丰富的水汽,切变线南移为暴雨提供了有利的动力条件。暴雨区与垂直速度及涡度所表现的上升区对应,并伴有高能高湿条件。同时,卫星云图上有中尺度云团,由于切变线南压作用,使得暖湿不稳定气流辐合上升加强,促进了中尺度云团的旺盛发展,使得强降水短时内迅速发生。研究这次局地强降水天气的机制,找到一些突发性强降水的预报着眼点具有明显的分析诊断意义。

ANALYSIS OF A ABRUPT HEAVY RAIN PROCESS IN QUJING DISTRICT ON 23 AUGUST,2004

A process of rare local torrential occurred in Qujng on 23 August ,20 04,the daily rainfall in Qujing broke the record of last 30 years.The cause of the heavy rainfall is analysed with the MICAPS data,GOES-9 satellite images.It is shown that this heavy rainfall process is caused by the interaction among the subtropical high and the lower-shear.The southwest flow on periphery of the sub tropical dynamical condition for this event. The rainfall region is correspondin g with the ascending region of vertical speed and vorticity ,and accompanied wi th the high energy and high wet regions. There is a developing mesoscale cloud c luster from the satellite image. image.Furthermore,the Lower-shear line southwa rds moving strengthened the ascending motion of warm and wet flow,provided adva ntage for mesoscale cloud development,this cause the torrential occurred at onc e.The analysis of this event will be as a reference of heavy rainfall forecast i n Qujing.