摘要
利用欧洲中期天气预报中心的ERA5再分析资料,分析中高纬度大尺度环流异常对2022年盛夏长江中下游地区大范围极端高温事件的影响。结果表明,此次极端高温异常主要受到东亚副热带异常反气旋和北部异常气旋的影响。该经向偶极型环流异常与北大西洋涛动(North Atlantic Oscillation,NAO)和英国-鄂霍次克海走廊型遥相关型(British-Okhotsk Corridor,BOC)密切相关。NAO正位相关联的副热带急流波列有利于副热带反气旋的形成。同时,正位相的BOC与丝绸之路遥相关耦合,有利于经向偶极型环流模态的形成。在该环流模态的影响下,对流层高层的南亚高压和西风急流明显增强且东伸,中低层西太平洋副热带高压增强西伸。异常高压控制下的下沉气流以及西风急流出口区右侧的下沉气流通过绝热下沉增温与晴空短波辐射增温,促进地表气温升高,进而引发极端高温异常。
This study investigates the influence of large-scale atmospheric circulations on the historically extreme hot days in the mid-lower branches of the Yangtze River basin in peak summer(July—August)2022.The results show that the hot weather is influenced by an anomalous anticyclone over extratropical East Asia and an anomalous cyclone over eastern Siberia.These meridional dipole circulation anomalies are related to both the positive phase of the North Atlantic Oscillation(NAO)and the British-Okhotsk Corridor(BOC)pattern.Concurrent with the positive phase of the NAO,a significant wave train propagates along the subtropical jet stream,contributing to the anomalous anticyclone over the mid-latitude region of East Asia.Additionally,the positive phase of the BOC pattern is usually coupled with the Silk Road pattern,which benefits the meridional dipole circulation over East Asia.Accompanying these meridional dipole circulation anomalies,both the South Asian high and the subtropical jet stream intensify and extend eastward in the upper troposphere,and the western North Pacific subtropical high also intensifies and extends westward in the lower and middle levels.Thus,the mid-lower Yangtze River basin is on the right side of the exit of the subtropical jet stream and is controlled by the anomalous high,which prohibits ascending motions and induces hot days by adiabatic warming,enhancing downward radiation at the surface.
作者
尹泽疆
魏维
杨崧
YIN Zejiang;WEI Wei;YANG Song(School of Atmospheric Sciences,Sun Yat-sen University,and Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai),Guangdong 519000,China;Guangdong Province Key Laboratory for Climate Change and Natural Disaster Studies,Sun Yat-sen University,Guangdong 519000,China)
出处
《大气科学学报》
CSCD
北大核心
2023年第3期345-353,共9页
Transactions of Atmospheric Sciences
基金
广东省基础与应用基础研究重大项目(2020B0301030004)
国家自然科学基金资助项目(41975074)
广东省基础与应用基础研究基金(2023A1515010908)
广东省气候变化与自然灾害重点实验室(2020B1212060025)
南方海洋科学与工程广东省实验室(珠海)创新团队建设项目(311021001)。
关键词
高温
急流
遥相关
high temperature
jets
teleconnections
