2017年梅雨期浙江中部连续暴雨过程的环流特征  

Analysis on the Circulation Characteristics of Continuous Meiyu Storm in Central Zhejiang Province in 2017

作　　者：周梅 许洪泽 郑朝霞 项素清 Zhou Mei;Xu Hongze;Zheng Zhaoxia;Xiang Suqing(Jinhua Meteorological Bureau, Jinhua 321000, China)

机构地区：[1]金华市气象局

出　　处：《气象与减灾研究》2019年第1期32-39,共8页Meteorology and Disaster Reduction Research

基　　金：浙江省气象局预报员专项(编号:2017YBY10);金华市气象科技计划项目(编号:2018-04)

摘　　要：利用常规气象观测资料、NCEP1°×1°的FNL再分析资料和FY-2E卫星云图资料对2017年梅汛期前后浙江中部大尺度环流背景进行分析,同时对梅汛期三次强降水过程的梅雨锋结构、对流层低层风场对中尺度对流系统发展的影响以及中尺度云团特征等进行了诊断分析。结果表明:1)进入梅汛期,贝加尔湖长波脊发展及长久维持,带状分布的西太平洋副热带高压较常年偏强,有利于冷暖空气交汇于浙江一带,形成范围大、持续时间长的强降水;2)在垂直方向上,高空西风急流的入口区右侧与低空急流核左前方相叠加,高低空急流耦合作用明显,为中尺度对流系统维持提供了必备的不稳定机制;3)三次强降水过程均具有正涡度带随时间东移的现象,揭示了梅雨锋区低值系统沿切变线东移的特点。其中,第三次暴雨过程正涡度东移特点最明显,对流层低层的有利动力条件导致中尺度对流系统的发展及强降水的出现;第二次过程的副热带西风急流中心风速明显较第一次和第三次小,但西风急流中心位置南移至30°—35°N,正好位于梅雨锋区上空,补偿了因急流风速减小对高层辐散的影响。Based on the data of conventional observation, NCEP 1°×1° FNL analysis and FY-2E satellite cloud images, large scale circulation background before and after Meiyu periods in central Zhejiang province in 2017 were analyzed, and the different structure comparison of Meiyu front in the three heavy precipitation processes and low troposphere wind impact on MCS development were also discussed in this paper. The results showed that: during Meiyu period, with the development and maintain for a long time of Lake Baikal long-wave ridge, the west Pacific subtropical high was stronger than that during the same period of normal years, which was favorable for the confluence of cold and warm air in Zhejiang, forming a large scale heavy precipitation with long duration;In vertical direction, the right side of high-level jet overlaid on the left-front side of LLJ core resulted in obvious coupling between the two systems, which provided the necessary instability mechanism for MCS maintenance. The positive vorticity zone moving eastward over time in the three heavy precipitation processes indicated the low-value system of Meiyu front move eastward along the shear line;The characteristic of positive vorticity in middle troposphere moving eastward was most obvious during the third heavy rainfall, which was favorable for the development of MCS;The wind speed in subtropical westerly jet stream during the second process was slower than the others, but the center position of westerly jet moved southward to 30°-35°N, which located in the Meiyu front zone, and compensated the impact on upper divergence of decreased jet stream wind speed.

关 键 词：暴雨 环流特征 梅雨锋 中尺度对流系统 

分 类 号：P458.121.1[天文地球—大气科学及气象学]