应用湿Q矢量分解理论诊断分析“05.7”梅雨锋暴雨

Diagnostic Analyses of a Meiyu Front Heavy Rain Process in July 2005 Using Wet Q Vector Partitioning Theory

摘要:

利用Q矢量分解理论对发生于2005年7月的一次江淮梅雨锋暴雨过程进行诊断分析,并对比分析了原非地转湿Q矢量(Q^*)和改进后的非地转湿Q矢量(Q^M)的诊断能力。结果显示:对流凝结潜热的释放对此次梅雨暴雨中尺度系统的形成和维持起到非常重要的作用;将Q^M分解为平行和垂直于等位温线两个方向后,发现在暴雨强盛阶段,低层大气是以大尺度辐合为主,中高层相反,且南北方向有次级环流出现,表明次天气尺度的持续性水汽汇集和正反馈机制是此次梅雨锋暴雨的关键因子。

Abstract:

Using the ageostrophic wet Q vector(Q^*),modified ageostrophic wet Q vector(Q^M) and Q vector partitioning theories,a Meiyu front weather process which occurred in the Jianghuai River Valley in July 2005 is diagnostically analyzed and the diagnosis ability of Q^* and Q^M compared.The results show that the release of the convective latent heat played an important role in the formation and maintenance of the meso-scale system.By dividing the wet Q vector into two parts of parallel and perpendicular to isotherms,it is shown that the large-scale convergence deminated at the low levels at the intensifying stage of the rainstorm,however,at the high levels,the situation was apposite,and meanwhile the meridionally secondary circulation appeared.All those show that the subsynoptic-scale persistent moisture convergence and the positive feedback mechanism are the key factors responsible for the rainstorm event.