一次中尺度对流复合体致洪暴雨成因分析

为了探索陕西暴雨天气发生发展的机制,采用天气学、动力诊断等方法对2011年7月5～6日陕西南部出现的暴雨过程进行分析。结果表明:中尺度对流复合体是造成此次暴雨的直接原因,强降水发生在中尺度对流复合体云顶亮温北边界的等值线密集区;沿海至陕西建立起水汽和温湿能的输送通道,高温高湿的暖湿空气源源不断地向暴雨区输送;不同暴雨阶段的中低层大气稳定性有明显的差异,对流不稳定和条件性对称不稳定是暴雨发展维持的重要机制;对流层低层较大的垂直螺旋度东侧可能预示着大暴雨的发生。

Analysis of a Flood Rainstorm Caused by MCC in Shaanxi

Using synoptic analysis and dynamical diagnosis methods,a heavy rain in southern Shaanxi occurring form 5 to 6 July 2011 is analyzed for finding out the development mechanism of Shaanxi rainstorm.The main conclusions are as follows: MCC is the direct influence system to the heavy rain and the large precipitation occurred in northern border of TBB intensive belt.Transmission channel of water vapor and temperature and humidity was established from coast to Shaanxi;The stability is obvious different at two stages of the rainstorm,the conditional symmetric instability and convective instability is an important mechanism for the storm development and maintenance.East of the larger helicity in lower troposphere may indicate the occurrence of the heavy rain.