一次江淮暴雨过程中干空气侵入的诊断分析

Diagnostic Analysis of Dry Intrusion in a Rainstorm Process

利用中尺度数值模式MM5(V3),对 2003年 7月 4日 20时至 5日 20时发生在江淮地区的一次梅雨锋暴雨过程进行模拟,并采用模式输出的具有较高分辨率和动力协调性的网格资料,就干空气侵入及其对暴雨过程的作用进行了诊断研究。结果表明,此次暴雨过程中有明显的干空气侵入,且干空气侵入对暴雨过程产生重要作用:干空气侵入将对流层高层高位涡带入低层,促进了对流层低层气旋及对流运动的发展,继而引起降水的增强。

The mesoscale numerical model MM5(V3) was used to simulate a heavy rain process on a Meiyu front in the Jianghuai area during the period from 2000BST July 4 to 2000BST July 5, 2003.The high spatial and temporal resolution model outputs were used to diagnose the dry intrusion and its effect on the heavy rain process.The results show that the dry intrusion play an important role in the development of the heavy rain process,and the dry air with high potential vorticity in the upper troposphere intruded into the lower layer,which promoted the development of cyclone and convection,and subsequently the enhancement of precipitation.