西藏昌都市2017年7月7-8日持续强降水过程的物理机制

The physical Mechanism for Continuous Strong Precipitation over Changdu City of Tibet from July 7 to 8,2017

利用昌都市站点降水观测资料和ERA-interim再分析资料,对2017年7月6日20:00~7月9日20:00西藏昌都市发生的持续强降水天气过程进行个例分析。通过分析大尺度大气环流作用、热力作用以及动力作用揭示此次持续强降水过程的发生和持续机制,分析发现:大尺度环流背景有利于冷暖空气在昌都市上空汇合,利于产生强降水;此次降水具备充分的水汽条件与强烈的上升运动,配合着中低层明显辐合与高层明显辐散。

Analyzed the process of continuous strong precipitation over Changdu City of Tibet from 8:00 p.m.July 6 to 8:00 p.m.July 9 by using the Changdu City’s precipitation observation data and ERAinterim reanalysis data.This study revealed the formation and maintenance mechanisms for this continuous heavy precipitation process through discussing the effect of large-scale atmospheric circulation,thermodynamic and dynamic conditions.The results showed:the large-scale atmospheric circulation was favorable to the convergence of cold and warm air over Changdu city which can lead to the formation of strong precipitation;This precipitation was the result of sufficient water vapor condition,strong upward vertical motion and strong convergence in lower troposphere and divergence in upper troposphere.