“0806”华南持续性暴雨诊断分析与数值模拟

用NCEP再分析资料、常规气象观测等资料,对2008年6月11—13日发生在华南地区的持续性暴雨的大尺度背景进行了分析,用MM5模式模拟出了暴雨的大尺度背景,利用模拟结果对这次暴雨过程的系统演变做了进一步的分析。结果表明:(1)西南涡是暴雨的直接影响系统,随着西南涡的东移,暴雨从广西北部一直推进到广东东南部。(2)中高纬稳定的两槽一脊的环流形势和偏南的西太平洋副高,及不断南下的小股冷空气,为这次暴雨提供了有利的中高纬环流背景冷空气条件;东亚夏季风偏南,越赤道气流偏强,给暴雨的维持提供了丰富的水汽条件。(3)模拟的结果验证了暴雨发生的大尺度环流背景,并在700hPa上模拟出了3个正涡度中心,是华南暴雨发生的动力因子。

Diagnostic analysis and numerical simulation of persistent torrential rain in south China in June 2008

Based on the reanalysis data of NCEP and the regular meteorological observation, the large scale background of persistent torrential rain on June 11-13, 2008 in south China is analyzed ,the large scale background environment has been simulated by high resolution MM5 model. The result shows that: (1) Southwest vortex was the direct impact system of the persistent torrential rain, as the vortex move eastward, the torrential rain moved from northern area of Guangxi to southeast area of Guangdong. (2) The stable circulation of two troughs and one ridge at middle and high latitudes, the more southward position of the subtropical high in the west Pacific and small-scale cold current continuously advancing south provided a favorable circulation cold air background condition of middle and high latitude area for the maintenance of the persistent torrential rain. Anomalously southern summer monsoon in East Asia and anomalously strong air current across equator provided abundant moisture for the maintenance of the persistent torrential rain. (3) The result of the simulation proves the large scale circulation background of the torrential rain, and three positive vorticities appeared on 700 hPa are the dynamical factor of the torrential rain.