8月内蒙古东部两次高空低涡型降雨对比分析

Comparative analysis of two upper-air vortex rainfall processes in eastern Inner Mongolia in August

本文运用常规地面自动气象站和多普勒天气雷达等监测数据及ERA50.25°×0.25°再分析资料,对比分析了2020年8月7-14日内蒙古东部呼伦贝尔市连续两次出现的高空低涡影响下显著不同性质降雨的天气学成因。研究结果表明:两次过程由上到下的配置分别是高空低涡,低空暖脊,地面倒槽和高空低涡,冷性涡旋,锋面气旋,低涡的冷、暖性和垂直结构差异是形成稳定性或对流性降雨的主因;两次过程垂直方向上分别表现为低层东南风转为中层西南风较大的垂直风切变和一致偏南风气流,深厚湿层和弱的垂直风切变利于产生稳定性降雨;≥28℃的中低层温度差对强对流天气有指示意义;比湿条件高不是对流性降雨雨量大的充分条件。

Based on the observation data of conventional automatic weather station and Doppler weather radar as well as ERA50.25°×0.25°reanalysis data,the Synoptic causes of rainfall with different properties under the influence of two consecutive upper-level low vortices in Hulunbuir city,eastern Inner Mongolia,from August 7 to14,2020 are analyzed.The results show that the top to bottom configurations of two processes were upper-air vortex,low-air warm ridge,surface inverted trough and upper-air vortex,cold vortex,frontal cyclone respectively,the difference of cold or warm and vertical structure of vortex is the main cause of stable or convective rainfall;the southeast wind in the lower layer changed to the southwest wind in the middle layer and the consistent southerly wind were respectively in the vertical direction of the two processes,the deep wet layer and weak vertical wind shear are conducive to stable rainfall;the temperature difference between the middle and lower levels greater than or equal to 28℃is indicative of intensive strong convective weather;high specific humidity conditions are not sufficient conditions for convective rainfall.