2011年7月29日山西大暴雨过程的多尺度特征

利用1°×1°的NCEP再分析资料、红外辐射亮温（TBB）、多普勒雷达和气柱水汽总量等资料,对2011年7月28-29日发生在山西境内的区域性暴雨进行多尺度特征分析。结果表明：（1）乌拉尔山阻高崩溃,西风槽东移、副高进退是此次暴雨发生的环流特征;（2）850 hPa低涡切变和700 hPa暖式切变线及地面冷锋是暴雨发生的中α尺度触发系统;（3）〉30 dBZ的雷达回波呈南北向位于地面冷锋与700 hPa切变线之间,雷达回波随地面冷锋和700 hPa切变线的东移而东移;（4）低空低涡切变受500 hPa强盛西南气流的引导向东北移动,暴雨落区始终与低涡切变相伴随;（5）暴雨过程山西境内共有9个中β尺度对流云团活动,山西西南部的暴雨主要由5个中β尺度对流云团的相继移入并在自动站极大风速风场切变线附近触发对流发展所致;山西东南部的大暴雨则是3个中β尺度对流云团合并发展的结果,中γ尺度气旋是导致局地大暴雨发生的直接影响系统;（6）暴雨发生在气柱水汽总量空间分布图中水汽锋的南部和东部及靠近气柱水汽总量的大值区一侧,水汽锋的形成比降水开始提前17 h,比暴雨发生提前24 h以上,对暴雨的短期、短时预报有指示意义。

Analysis on the Multi-Scale Characteristics of the Rainstorm in Shanxi Province on 29 July 20 1 1

Based on the NCEP reanalyzed data（1° × 1°）,infrared radiation bright temperature,Doppler radar data and the total column water vapor content data,the multi-scale characteristics of the regional rainstorm which occurred in Shanxi on 28 - 29 July 2011 were analyzed.Results were as follows：（1） The collapsing of Ural blocking high,westerly trough moving eastward,the advance and retreat of the subtropical high were the circulation characteristics of the rainstorm;（2） The vortex shear line on 850 hPa,warm shear line on 700 hPa and the cold front on surface were the meso-α-scale system triggering rainstorm occurrence;（3） The radar echo more than 30 dBZ lied between the surface cold front and the 700 hPa shear line,and moved eastward with them going to east;（4）The lower level vortex shear line was guided to northeast by the strong southwest airflow on 500 hPa,while the rainfall area always followed the shear line;（5） During the rainstorm process,there were nine active meso-β-scale convective cloud clusters totally in Shanxi Province,and five of them entered in Shanxi one after the other and triggered the rainstorms in southwestern Shanxi nearby the shear lines of extreme wind of automatic stations.While the rainstorm in southeastern Shanxi was the result of mergence and development of three meso-β-scale convective cloud clusters,and the meso-γ-scale cyclone directly leaded to the occurrence of the local torrential rain;（6） The rainstorm occurred in the south and east areas of the water vapor front,as well as in the side of the high value area of the total column water vapor content.The formation of the water vapor front was 17 hours ahead of precipitation occurrence,and at least 24 hours ahead of the rainstorm appearence,which had a great significance in short-range and short-time weather forecast.