一次梅雨锋上中尺度气旋波引发的特大暴雨过程分析

Analysis of an excessive rainstorm event initiated by a mesoscale cyclonic wave along the Meiyu front

利用新一代天气雷达、卫星、自动气象站、风廓线雷达、PWV/GPS、GFS/NCAR再分析场和常规天气资料,针对2011年6月10日发生于武陵山东侧鄂湘交界(通城附近)的特大暴雨过程,重点分析了梅雨锋上中尺度扰动系统的发生、发展过程以及与之联系的中尺度对流系统结构特征。结果表明:(1)特大暴雨过程与两个中尺度气旋波扰动发展形成的中尺度对流系统共同影响有关,而锋前暖低压倒槽内中尺度对流系统后向传播对暴雨形成和加强起到非常重要的作用。(2)武陵山东侧鄂湘交界区域是梅雨锋上中尺度气旋波新生或加强的重要源地之一,长江中游复杂地形下有利的动力和热力因素起到重要作用。(3)中尺度对流系统的发生、发展与中尺度气旋扰动有密切关系,雷暴单体集中在冷、暖锋附近和涡旋中心附近强烈发展,并在气旋波系统组织下,降水回波整体具有冷暖锋结构特征的逗点涡旋、涡旋、"S"和"人"字等形态特征。

By using the data from the CINRnD,satellite,automatic meteorological stations, wind profiler radars, the PWV/GPS, the GFS/NCnR reanalysis and the conventional observation,an extraordinary rainstorm event,occurred in the east of the Wuling Mountains on the Huhei-Hunan border（near Tongcheng） on 10 June 2011,was analyzed focusing on the development of mesoscale disturbance systems along the Meiyu front and the associated structure characteristics of the mesoscale convective system. The results showed that：Firstly,the excessive rainstorm was related to the combined effects of mesoscale convective systems formed via the growth of two mesoscale cyclonic wave perturbations,and the back-propagation of mesoscale connective systems in the warm low upend trough ahead of the cold front played a significant role in the rainfall formation and enhancement. Secondly,the area in the east of the Wuling Mountains on the Hubei-Hunan border was one of the important seedbeds,where mesoscale convective cyclonic wave generate or strengthen. The favorable factors of thermodynamics and kinetics induced by the complicated terrain around the middle reach of the Yangtze River played important roles. Finally,the development of mesoscale connective systems was closely related to mesoscale cyclonic disturbances. Thunderstorm cell centralized and developed intensely near the cold/warm front and the center of the vortex. And organized by the strong cyclonic wave system,the precipitation echo manifested some features with the cold and warm front structure as a whole,such as the comma-shaped,vortex-shaped,“S”-and herringbone-shaped,and so on.