2005年6月华南特大连续性暴雨的环境条件和中尺度扰动分析  

A study of environment and mesoscale convective systems of continuous heavy rainfall in the South of China in June 2005

作　　者：慕建利[1] 王建捷[2] 李泽椿 

机构地区：[1]南京信息工程大学大气科学学院 [2]北京市气象局,北京100089 [3]国家气象中心,北京100081

出　　处：《气象学报》2008年第3期437-451,共15页Acta Meteorologica Sinica

基　　金：我国南方致洪暴雨监测与预测的理论和方法研究(2004CB418306)

摘　　要：利用常规观测站、地面加密站资料、卫星红外云图TBB和NCEP再分析资料,对2005年6月19—24日发生在广东的特大连续性暴雨过程进行了分析。天气分析表明:高空南亚高压前部的强辐散场,500hPa河套阻塞高压以及低层低涡切变线横卧在江淮一带、低空急流源源不断地向华南输送暖湿气流的这种大尺度环流形势和相应的大范围动力热力及水汽条件,决定了暴雨的多发时期和持续性;区域暴雨多发期内5次强降水的具体发生和间歇,则与暴雨区大气动力、热力及水汽条件的5个α中尺度时间变化与震荡密切联系并受其影响;暴雨区动力条件的α中尺度时间变化与特定的大尺度环流背景下高低空急流的演变有密切的关系。降水的中尺度特征分析表明:暴雨过程中5场暴雨的发展和间歇对应5个α中尺度系统的发展和减弱,暴雨是由19个β中尺度系统直接造成19个β中尺度大雨团形成。进一步分析表明:强降水主要发生在地面静止锋和锋前暖区的中尺度切变线(或中尺度辐合线)和中尺度涡旋或中尺度辐合中心附近,中尺度涡旋内的降水是由飑线上γ中尺度对流单体形成的"列车效应"产生的,而中尺度切变线附近的降水则是飑线的发展合并加强产生的。发生在冷式切变线附近的强降水移动速度较快,发生在暖式切变线附近的强降水移动缓慢,发生在辐合中心的强降水在原地发展达最强后随辐合中心转为切变线减弱或直接在原地减弱消失而结束。A process of the heavy rainfall on 19-24 June 2005 in the Guangdong province was analyzed using the reanalysis data of NCEP and the special observational data including automatic meteorological observing stations data and satellite images.The results indicate that successive heavy rainfall occurred under favorable large-scale circulation backgrounds,including the strong divergence on the fore-edge of the South Asia High in the upper level,the Hetao bloking in the middle level,the low vortex-shear line in the low level over the Changjiang-Huaihe River valley,and the low-level jet,which transferred the abundant vapor from the Bengal Bay and South China Sea to the southeast of South China.Five strong convective rainstorm processes had close relationship with the developing and weakening of five meso-α-scale convective systems,respectively.And meso-α-scale temporal evolvement of dynamical condition in the precipitation area had a tight relationship with the change of upper-level jet and low-level jet.The automatic meteorological observing station data and satellite images show that the five heavy rainfall processes were consisted of nineteen meso-β-scale rain cores within nineteen meso-β-scale cloud clusters.The precipitation mainly appeared in mesoscale shear lines or convergence lines,and mesoscale vortices or convergence centers.The precipitation in the mesoscale eddy resulted from the ＂train effect＂ produced by successive passages of several meso-γ-scale convective cells,and the mergence and intensification of squall lines with several meso-γ-scale echoes caused the convective precipitation in the vicinity of shear lines.The moving speed of the heavy precipitation areas in the warm shear lines was slower in comparison with that of the rainstorm in the cold shear lines,while the heavy rain in the convergence centers developed at first and then weakened stationary when the centers evolved into shear lines.

关 键 词：特大持续性暴雨 环境条件 高低空急流 Β中尺度对流系统 

分 类 号：P458.2[天文地球—大气科学及气象学]