台风海葵引发浙西山区大暴雨的成因

Causation Analysis of Severe Torrential Rain Process in Mountain Areas of Western Zhejiang Triggered by Typhoon Haikui

利用中尺度数值模式WRF,结合多普勒雷达资料、卫星TBB资料和自动站资料对2012年8月6—9日由台风海葵引发的杭州西部山区强暴雨洪涝灾害进行分析。结果表明,登陆台风内部的螺旋云带中有多个中尺度云团活动,云团不断从台风螺旋云带内部分裂生成,并有一个从加强发展到逐渐消亡的过程,正是在中尺度云团的直接作用下,给台风经过地区造成了一次又一次的强降水,导致了浙西北等地区持续不断发生暴雨,因此,中尺度系统是造成台风暴雨的直接原因;台风外围的东北风、西北风和偏西风在有利地形配合下,往往会汇合形成中尺度辐合线,未来强降水区域也基本落在中尺度辐合线附近区域,中尺度辐合线是触发暴雨对流发生、发展的重要系统;浙江杭州西北部山区地形对于台风暴雨主要体现在增幅作用,对台风路径、降水范围影响不大。

The WRF (Advanced Weather Research and Forecasting modeling system)was employed to sim-ulate the local severe rainstorm process caused by typhoon Haikui over the northwestern of Zhejiang Prov-ince from 6 to 9 August 2012.The analysis of the simulation result combined with Doppler radar data, TBB (Temperature of Black Body)data,and automatic weather station data shows that there are several mesoscale systems embedded in spiral cloud band of the landed typhoon.Mesoscale systems develop,rein-force and weaken after division from spiral cloud band.It brings the local severe rainstorms over the north-western of Zhejiang Province due to the direct effect of mesoscale systems.There generates the mesoscale divergence line which is responsible for the rainstorm by northeasterly flow and northwesterly current un-der advantageous topography.The topography of the northwestern of Zhejiang Province can increase the intensity of rainfall but is not so related to typhoon track and range of rainfall.