淮河流域一次梅雨锋暴雨的中尺度动力特征分析

针对2007年7月8日发生在苏皖淮河流域的暴雨,采用WRF中尺度数值模式模拟结果、FNL每日4次1°*1°再分析资料、6h地面实况观测降水资料和FY-2相当黑体亮温TBB资料对该次降水的发生、发展过程进行了分析研究。结果表明:(1)该次降水在有利的大气环流形势下,强降水发生在呈准东西向分布的梅雨锋上。位于蒙古国与我国华北—东北交界处上空的切断低压给淮河流域输入了冷空气。冷空气与西南低空急流带来的暖湿气流交汇,增强了大气斜压性;(2)正的非热成风涡度的发展促进了高层相对于低层的辐散减压,有利于垂直上升运动的发展;(3)低空强急流带所形成的动力、热力和水汽条件对暴雨落区位置产生了重要影响。

Mesoscale dynamic feature analysis of a rainstorm happening along plum rains front in Huaihe River Basin

In view of the rainstorm which happened in Huaihe River Basin on July 8,2007,this essay adopted the simulation results of WRF mesoscale numerical model,the FNL reanalysis data,the precipitation data from 6-hour observation of the practical condition and the TBB data from FY-2 satellite to analyze and investigate the process of precipitation.Results show that:(1) The precipitation happened under the favorable situation of atmospheric circulation and the heavy precipitation happened along plum rains front which distributes in the direction of quasi-east-west.The cut-off low pressure which lies over the boundary of Mongolia and north and northeast China inputs into Huaihe River Basin cold airstreams which intersected with the warm and humid airstreams brought by the jet stream in the minimum altitude of southwest.The intersection enhances the atmospheric baroclinicity.(2) The development of positive non-thermal-wind vortices helps the divergence decompression of high level relative to lower level and benefits the ascending motion.(3) The jet stream band formed in the low altitude creates suitable conditions of power,heat and vapor which greatly influence the location of rainstorm-bands.