成都地区一次极值大暴雨天气过程成因初步分析

A Preliminary Analysis of the Cause of an Extreme Rainstorm in Chengdu Area

为提高持续大暴雨天气过程的预报准确性,利用高空、地面、卫星等气象资料,通过天气学、卫星气象学等对2020年8月10-12日成都地区一次创历史记录的持续大暴雨天气过程进行分析。结果表明:此次持续大暴雨天气过程是在成都地区500 hPa持续受低涡和低槽影响,大气低层的持续强烈辐合和高层的辐散抽气耦合及地面冷空气的共同作用下产生。低层偏东暖湿气流在成都西部沿山地形抬升作用下,进一步增强了成都市西部的降水;此次暴雨天气过程强降水有两个阶段,分别出现于2020年8月11日06-17时、8月11日19时至12日12时。强降水出现的两个阶段成都地区低空急流长时间维持,处于持续高湿、高能不稳定状态,有利于大暴雨产生;成都西南部强降水中心反复出现强降水云团,最低云顶亮温在-82℃以下。

In order to improve the prediction accuracy of the process of continuous heavy rainstorm,the process of a continuous heavy rainstorm weather process which set a historical record from August 10 to August 12,2020 in Chengdu area was analyzed by using the meteorological data of high altitude,ground and satellite,etc.The analysis results show that the continuous heavy rain weather process is caused by the continuous influence of low vortex and trough in Chengdu area at 500 hPa,the continuous strong convergence in the lower atmosphere and the coupling effect of divergence and suction in the upper atmosphere,as well as the cold air on the ground.The easterly warm moist air in the lower layer is uplifted along the mountain terrain in the west of Chengdu,which further enhances the precipitation in the west of Chengdu.There were two stages of heavy precipitation during the rainstorm,which occurred from 6:00 to 17:00 on August 11,2020,and from 19:00 on August 11,2020 to 12:00 on August 12,2020.The two stages of heavy precipitation in Chengdu sustained the low-altitude jet stream for a long time,which was in the unstable state of continuous high humidity and high energy,which was conducive to the generation of heavy rain.Heavy precipitation cloud clusters repeatedly appeared in the heavy precipitation center in southwest Chengdu,and the lowest bright cloud top temperature was below-82 ℃.