青海大通地区一次罕见的大到暴雨过程分析

2013年8月21日,青海西宁大通县桥头镇出现了创历史极值的大暴雨天气过程,此次暴雨的降水空间集中,降水量大,实为罕见.利用常规天气图实况资料、NCEP分析场资料、多普勒雷达探测资料进行分析,结果表明:(1)副热带高压稳定维持,引导西南暖湿气流北上,新疆脊前下滑的短波槽携带冷空气南下,冷暖空气在青海东北部交绥,为大通特大暴雨提供了有利的环流条件.(2)暴雨发生过程中有强盛的水汽输送和水汽通量输送;暴雨区水汽的辐合以及暴雨发生前大气热力不稳定为暴雨的发生提供了条件.(3)对流云团在东移南压过程中依次经过大通县城,表现为列车效应,并对应此次最大小时降雨量.径向速度场在大通地区存在着风场辐合,这种形式对本次强降水的持续提供了有利的动力条件;VIL数值的大小很好的反映了降水强度,VIL的大小、影响范围和移动方向对应降水强度、发展及消亡;雷达降水量图对本次强降水过程的降水量及落区有一定指示意义.

A Rare Heavy Rain Process Analysis of Datong Country in Xining of Eastern Qinghai

August 21 ,2013 ,a record extremes of heavy rain process appeared in Datong Country of Xin-ing Qinghai province .The concentration of precipitation space ,heavy precipitation of this process is rare . Using conventional weather charts ,NCEP analysis of field data ,Doppler radar data were analyzed ,the re-sults show ：（1 ）remained stable subtropical high ,guide the southwest warm and damp airflow towards Northward ,the results of the falling short wave trough before Xinjiang ridge to carry cold air southward , the interaction of cold and warm air in northeastern Qinghai ,which provides favorable circulation condi-tions for this heavy rainfall in Datong .（2）there are powerful water vapor trasport and vapor flux transport in this rainstorm ;rainstorm moisture convergence zone and pre - storm atmospheric instability provide conditions for the occurence of rainstorm .（3）convective clouds in the process turn eastward and southward through Morgan County ,expressed as the train effect ,and corresponds to the maximum hourly rainfall .Ra-dial velocity field in Datong area exists wind convergence ,this form provide favorable conditions for this rainfall persistence ;VIL value of a good size reflects the intensity of preciptation ,VIL size ,influence scope and direction movement corresponds to the intensity of precipitation ,development and demise ;radar rainfall figure indicates a certain significant to this drop zone in the heavy rainfall process .