惠州高潭一次特大致洪暴雨过程分析

Analysis of an Unusually Heavy,Flood-Causing Rain at Gaotan,Huizhou

利用2013年8月16—17日CFSR的0.5°×0.5°网格资料以及自动监测站数据,分析了发生在惠州市惠东县高潭镇及其附近地区的特大致洪暴雨过程,结果得到:"尤特"登陆后残余环流长时间的少动维持,有利于西南(偏南)气流源源不断向高潭及其附近的暴雨区输送充沛的暖湿水汽;西南气流与偏南气流的交汇形成中尺度能量锋和露点锋,有利于暴雨的发生发展;强降水期间,高潭及其附近地区上空存在不稳定层结和较强的上升运动,以及低层辐合高层辐散的有利配置,另外,强降水区及其西侧的对流层中还存在着一个逆时针旋转的垂直风场;"U"型地形和喇叭口地形及近地面层的风场辐合,为白盆珠至高潭附近地区的暴雨起到非常重要的增幅作用。

Using the 0. 5 × 0. 5 gridpoint data of CFSR and records from automatic watch stations from August 16- 17,2013,this work studies an unusually heavy,flood-causing rain that took place in the town of Gaotan,Huidong county,Huizhou city. The results are shown as follows. Typhoon Utor left behind a pattern of circulation that stagnated and maintained for extended time,constantly supplying（ generally） southerly flows to Gaotan and its adjacent area to feed the zone of heavy rain with abundant amount of warm and humid water vapor. A southwesterly converged with a southerly to form mesoscale fronts of energy and dew point that helped the heavy rain to generate and develop. During the rain,there were unstable stratification and intense ascending motion as well as a favorable allocation of low-level convergence and upper-level divergence in the region. Besides,a counterclockwise rotating vertical wind field was also present in the zone of heavy rain and the area to its west. The local U-shaped and trumpet-shaped terrain as well as near-surface convergence of a surface wind field played an essential role in enhancing the rain in the studied region.