弱天气强迫背景下浙江两次暖区大暴雨过程成因分析  

Analysis of Causes of Two Warm-Sector Heavy Rainfall Processes in Zhejiang Province under Weak Synoptic Scale Background

作　　者：钱卓蕾 马洁华[2,3,4,5] 沈晓玲 钱月平 QIAN Zhuolei;MA Jiehua;SHEN Xiaoling;QIAN Yueping(Shaoxing Meteorological Office,Zhejiang,Shaoxing 312000;Climate Change Research Centre,Chinese Academy of Sciences,Beijing 100029;Nansen-Zhu International Research Center,Institute of Atmospheric Physics,Chinese Academy of Sciences,Beijing 100029;Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters,Nanjing 210044;National Institute of Natural Hazards,Ministry of Emergency Management of China,Beijing 100085)

机构地区：[1]浙江省绍兴市气象台,绍兴312000 [2]中国科学院气候变化研究中心,北京100029 [3]中国科学院大气物理研究所竺可桢南森国际研究中心,北京100029 [4]气象灾害预报预警与评估协同创新中心,南京210044 [5]应急管理部国家自然灾害防治研究院,北京100085

出　　处：《气象科技》2022年第5期713-723,共11页Meteorological Science and Technology

基　　金：国家重点研发计划(2017YFC1502304)资助。

摘　　要：2021年6月9日夜间和6月12日夜间,浙江绍兴出现了两次暖区大暴雨过程,主、客观预报均出现较大偏差。本文利用地面加密自动站、多普勒雷达资料以及ERA5再分析资料,对这两次过程的环流场、触发机制和中尺度对流系统演变情况进行分析,结果如下:(1)两次过程均发生在弱天气强迫背景下,“609”过程是在边界层急流的作用下发生的,“612”过程发生在副高边缘;(2)“609”过程中垂直螺旋度大值中心最高伸展至对流层中层,上游位涡扰动不断向下游输送,促使暴雨区位涡扰动持续发展;“612”过程中垂直螺旋度大值中心仅伸展至对流层低层,等熵面上存在干冷空气侵入,有利于位涡扰动迅速加强;(3)两次过程的触发机制均为β中尺度辐合线,中尺度对流系统沿着辐合线不断发展,并处于“准静止”状态,造成大暴雨,“609”过程β中尺度系统较“612”过程停滞时间更长,同时受迎风坡地形抬升作用影响,降水总量更大。On the night of June 9th and June 12th,2021,Shaoxing,Zhejiang Province,experienced two warm-sector heavy rainfall.Both subjective and objective forecasts show large deviations.Using the ground-based automatic station,Doppler radar observation data and ERA5 reanalysis data,the circulation field,triggering mechanism and mesoscale convective system evolution of the two processes are analyzed.The results are as follows:(1) Both processes occurred under the background of weak weather forcing.The “609” process took place under the action of boundary layer jets.While the “612” process occur red at the edge of the subtropical high.(2) During the “609” process,the centre of the large vertical helicity stretched up to the middle troposphere,and the upstream potential vorticity disturbance was continuous transportation,promoting the continuous development of the potential vortex disturbance in the rainstorm area.The large vertical helicity centre of the “612” process only extended to the lower troposphere,and there was dry and cold air intrusion on the isentropic surface,which was conducive to the rapid strengthening of the potential vortex disturbance.(3) The triggering mechanisms of the two processes were both β mesoscale shear lines.The mesoscale convective system developed continuously along the shear line and was in a “quasi-static” state,causing heavy rainstorms.The β mesoscale shear line and the mesoscale convective system of the “609” process had a longer stagnation time than the “612” process and were affected by the windward slope’s uplift,so the total amount of precipitation was greater.

关 键 词：弱天气强迫 暖区暴雨 中尺度辐合线 等熵位涡 地形 

分 类 号：P458[天文地球—大气科学及气象学]