98.7暴雨中尺度系统发展的视涡源涡度变率诊断分析

Diagnostic analysis of the apparent vorticity source and vorticity change-rate of the developing mesoscale system during the 98.7 heavy rainfall

利用 MM5输出的高分辨率资料和视涡源与总涡源诊断方程对“98.7”特大暴雨的涡度场、视涡源、总涡源进行了诊断分析 .结果揭示 :此次暴雨的发生和发展与其视涡源、总涡源的生成和发展直接相关 .正视涡源柱和总涡源柱的存在及强烈发展是强暴雨中尺度系统发生发展的主要动力机制 ,这种机制有利于突发性特大暴雨发生 .暴雨的落区基本处于视涡源、总涡源中心位置的下方 .因而 。

In this paper, the vorticity and apparent vorticity source as well as vorticity change-rate were diagnosed by using the high spatial resolution simulated output data from MM5 during the '98.7' heavy rainfall. It showed that the genesis and development of the '98.7' heavy rainfall were directly related to both apparent vorticity source and total vorticity source of the mesoscale system with heavy rainfall. Analyses indicated that the existence and intensive development of the positive apparent vorticity source column and total vorticity source column were a key dynamic mechanism in the genesis and development of the mesoscale system with severely heavy rainfall and this mechanism is favorable to the genesis and development of abrupt extraordinary heavy rainfall. The region of heavy rainfall was basically located below the centers of the apparent vorticity source and total voritcity source and therefore, the region and intensity of the apparent vorticity source and total voritcity source provided some important reference for forecasting the intensity and location of heavy rainfall.