2018年5月浙江省极端高温气候特征及环流背景  

Analysis on Climatic Characteristics of Extreme High-temperature in Zhejiang Province in May 2018 and Associated Large-scale Circulation

作　　者：马浩[1] 刘昌杰 钱奇峰 徐哲永 肖晶晶[1] 杨明[4] 高大伟[1] MA Hao;LIU Changjie;QIAN Qifeng;XU Zheyong;XIAO Jingjing;YANG Ming;GAO Dawei(Zhejiang Climate Center,Hangzhou 310017,China;School of Earth Sciences,Zhejiang University,Hangzhou 310027,China;Zhoushan Meteorological Bureau of Zhejiang Province,Zhoushan 316021,Zhejiang,China;Zhejiang Meteorological Information and Network Center,Hangzhou 310017,China)

机构地区：[1]浙江省气候中心,浙江杭州310017 [2]浙江大学地球科学学院,浙江杭州310027 [3]浙江省舟山市气象局,浙江舟山316021 [4]浙江省气象信息网络中心,浙江杭州310017

出　　处：《干旱气象》2020年第6期909-919,共11页Journal of Arid Meteorology

基　　金：浙江省基础公益研究计划项目(LGF19D050001);中国气象局预报员专项项目(CMAYBY2019-048);国家重点研发计划项目(2018YFC1505601);浙江省气象局预报员专项项目(2018YBY02);中国气象局青年英才专项共同资助。

摘　　要：2018年5月浙江省出现历史罕见的极端高温热浪,全省大部极端最高气温达36℃以上,局部地区超过40℃,多站高温日数和极端最高气温破历史同期纪录;高温累积站次和有效积温均居历史第一位。利用浙江省66个常规气象站的逐日观测资料、NCEP/NCAR再分析资料以及国家气候中心西太副高环流特征量指数资料等对此次高温过程的环流特征进行诊断分析,结果表明:西太平洋副热带高压偏强、偏西、偏北是造成极端高温热浪的直接原因,副高的“西伸”与南亚高压的“东进”相向而行;在副高控制下,850 hPa中国东南部至西北太平洋区域形成强大的反气旋式风场异常,浙江地区盛行下沉气流;5月14—18日强高温过程期间,短波辐射通量表现为正距平,“辐射增温”与“下沉增温”的叠加效应进一步加剧了高温的极端性。副高强度和位置的变化与热带和中纬度环流关系密切。海洋性大陆对流活动增强、热带中太平洋和北印度洋对流异常旺盛、南海地区对流减弱、西太平洋无台风生成均是副高增强的有利因素;200 hPa西风急流轴偏北,利于西太副高的稳定维持。There was a peculiarly strong heat-wave event in May 2018 in Zhejiang Province.The extreme maximum temperature(EMT)in most areas was higher than 36℃and in a few regions it could reach 40℃.The EMT and high-temperature days(NHD)in many stations broke historical record.The accumulated station-high-temperature days and effective accumulated high temperature both ranked the first in observational record.Based on daily observations at 66 normal stations in Zhejiang Province,NCEP/NCAR reanalysis data,and circulation indices of western Pacific subtropical high(WPSH)provided by National Climate Center,a diagnostic analysis was conducted to illustrate the large-scale circulation cause for such extreme high-temperature event.The results indicate that an enhanced,northward and westward western-distributed WPSH,which accompanied by eastward-march of the south-Asia high,was the direct reason for such extreme heat-wave event.Under the control of WPSH,broad anticyclonic horizontal wind anomaly formed in the region of southeast China-northwest Pacific on 850 hPa,and downward flow prevailed over Zhejiang region.During 14-18 of May 2018,positive anomaly of short-wave radiation flux and the subsident air worked together to intensify the extremity of prominent heat-wave.The change of intensity and location of WPSH was intimately linked with tropical and middle-latitude circulation.More supervital convection in Marine Continent,tropical middle Pacific and north Indian Ocean,weakened convective activity in south China Sea,decreased typhoon in tropical western Pacific acted jointly to enhance WPSH,while in mid-latitude,northward-placed westerly jet on 200 hPa made for stable maintenance of WPSH.

关 键 词：春季高温 高温热浪强度 西太平洋副热带高压 热带环流 中纬度环流 

分 类 号：P423.3[天文地球—大气科学及气象学] P434