2019年浙江省梅雨异常特征及成因分析  

Analysis of Abnormal Characteristics and Causes of the 2019 Meiyu in Zhejiang Province

作　　者：杜雪婷 刘汉华 马昊 Du Xueting;Liu Hanhua;Ma Hao(Zhejiang Weather Modification Center,Hangzhou 310051,China;Zhejiang Meteorological Observatory,Hangzhou 310051,China)

机构地区：[1]浙江省人工影响天气中心,杭州310051 [2]浙江省气象台,杭州310051

出　　处：《气象与环境科学》2023年第1期7-15,共9页Meteorological and Environmental Sciences

基　　金：浙江省青年项目(2021QN02);浙江省气象局重点项目(2018ZD02);浙江省一般项目(2017YB02)。

摘　　要：利用NCEP/NCAR再分析资料、浙江省常规气象资料及梅雨特征指数等资料,对2019年浙江省梅雨异常特征及成因进行了分析。结果表明:(1)2019年浙江省入梅和出梅均偏晚7天,暴雨过程频繁,短时雨强强,降水量异常偏多,比常年同期偏多115%,“冷黄梅”特征明显,气温为近20年同期最低。(2)对流层高层西风急流北跳偏晚、中层副热带高压北跳偏晚、低层夏季风加强北涌偏晚,导致2019年浙江省入梅偏晚;7月上旬西风急流的减弱南退,副热带高压和夏季风的阶段性南落,导致浙江省出梅偏晚。(3)梅汛期期间,南亚高压和西太平洋副热带高压的异常偏强、高低空急流的有利耦合、强劲的西南季风带来的充足水汽、中高纬“两槽一脊”形势的维持,导致冷暖空气长时间在浙江省上空汇合,造成2019年浙江省梅汛期降水异常偏多。(4)高空冷涡活动频繁,有利于冷空气不断南下;浙江省梅汛期期间降水异常偏多,上空对流活动多,云系多,晴天少,是造成浙江省“冷黄梅”现象出现的关键原因。Based on the NCEP/NCAR reanalysis data,the conventional observation data and Meiyu characteristic index,the characteristics and causes of abnormal Meiyu in 2019 in Zhejiang Province are analyzed.The results are as follows:(1)The beginning and ending dates of Meiyu in 2019 were 7 days later than normal.The rainstorm processes occurred frequently,and the intensity of short-time severe precipitation was strong.The rainfall amount was increased by 115%during the Meiyu season in 2019,much more than that in the same period of normal years.The characteristic of“cold Huangmei”was obvious,and the temperature was observed the lowest in the same period in the past two decades.(2)The late northward-moving of westerly jet in the upper troposphere,the late northward-developing of western Pacific subtropical high in the middle troposphere and the late northward-blowing of the East Asian summer monsoon in the lower troposphere jointly resulted in the late onset of Meiyu in Zhejiang Province in 2019.In early July,the westerly jet weakened,retreating southward,and the subtropical high and summer monsoon withdrew southward in a phased step led to the later ending of Meiyu in Zhejiang Province.(3)During the Meiyu season,the extremely strong south Asian high and western Pacific subtropical high,the favorable coupling of upper and lower jets,the abundant water vapor brought by the strong southwest monsoon,and the maintenance of the two troughs and one ridge pattern in middle-high latitudes caused the convergence of cold and warm airs over Zhejiang Province for a long time,thus resulting in abnormally more heavy rainfall in 2019 in Zhejiang Province.(4)The frequent activities of upper-air cold vortex were beneficial to cold air continuously pushing southward.In addition,abnormally heavy rainfall during the period of Meiyu,the more convective activities,the more clouds and the fewer sunny days were the key reasons for the appearance of“cold Huangmei”phenomenon in Zhejiang Province.

关 键 词：梅雨 异常特征 异常成因 冷黄梅 

分 类 号：P468.024[天文地球—大气科学及气象学]