低纬高原西南涡暴雨分析

Analysis on Southwest Vortex Rainstorm in Lower Latitude Plateau of China

选取了由西南涡造成的低纬高原暴雨的8个个例,利用中尺度滤波和物理量诊断方法,对低纬高原西南涡暴雨进行了分析研究.研究表明,向东南方向移出的西南涡是造成低纬高原暴雨的重要天气系统,暴雨主要出现在西南涡的西南象限的中尺度辐合线、变形场和气旋之中.造成低纬高原暴雨的西南涡是比较深厚的,其正涡度区在垂直方向通常可达300～400 hPa.这种西南涡不仅具有动力性的作用,而且其后部常伴有较强的冷空气活动.正是由于西南涡的动力扰动、冷空气活动和偏南暖湿气流的爬坡抬升共同导致了暴雨的发生.

In this paper the eight southwest vortex cases moving southeast were selected and their composited flow fields and the mesoscale filter fields were investigated. It has been found that the heavy rain mainly occurred in their southwest quadrants. The mesoscale systems of convergence line and field of deformation and vortex were the direct weather systems which caused rainstorm. These southwest vortexes were deeper and could reached up 300 hPa levels or 400 hPa levels. The rainstorms is to be brought by the dynamic disturbance and cold air moving and southwestern warm wet air forcing climbing.