四川盆地东北部中尺度MCS暴雨过程分析

2009年6月19日凌晨至23时四川盆地东北部生了一次由MCS单体带来的大暴雨天气过程。本文主要对该大暴雨过程的天气尺度环流背景、中尺度系统特征和地形作用等进行了分析。结果显示:(1)高空低槽和地面冷锋位于四川盆地北部为此次暴雨发生提供了有利的大尺度背景;(2)卫星云图及多普勒雷达回波表现出本次暴雨过程的直接系统是中尺度MCS单体;(3)能量、动力及水汽等的时空分布有利于MCS在四川盆地东北部产生;(4)非平衡值显示在MCS发展前几个小时其附近区域的大气已由平衡状态转为较强的非平衡状态,而在暴雨最强时刻,大气的非平衡性减弱并逐渐转为的准平衡状态;(5)大巴山地形抬升垂直速度对大暴雨的发生有促进作用。 

Analysis on A Heavy Rain Process Caused by Meso-Scale MCS in the Northeastern Sichuan Basin

A heavy rainstorm cased by MCS occurred in the Northeast of Sichuan basin on 19 June 2009.This paper main analysed the large-scale circulation background, the mesoscale characteristics and the orographio prepitation of the heavy rainstorm process.The results showed that:(1) The upper trough and surface cold front in the North of Sichuan basin provided a favorable large-scale circulation background for the rainstorm. (2) Satellite image and radar echo indicate that MCS is the direct system leading to the heavy rainstorm; (3) The MCS occurred at the Northeast of Sichuan basin was caused by the high energy, favorable dynamic condition and vapor condition, etc. (4) Several hours before the occurrence of heavy rain, the atmospheric motion was already strongly unbalanced.While at the peak moment of the precipitation intensity, the unbalanced status gradually changed into a balance status. (5) The vertical velocity caused by DaBa mountain has promoted the heavy rainstorm occurred.