冬季四川盆地霾天气的环流特征及其对前期青藏高原热力作用的响应  

Circulation Characteristics of Haze Weather over the Sichuan Basin in Winter and Its Response to the Thermal Action of the Tibet Plateau in the Early Stage

作　　者：罗玉 陈超[4] 赵鹏国 刘佳[1] 徐路扬[5] LUO Yu;CHEN Chao;ZHAO Pengguo;LIU Jia;XU Luyang(Climate Centre of Sichuan Province,Chengdu 610072;Plateau Atmosphere and Environment Key Laboratory of Sichuan Province,Chengdu 610225;Chengdu University of Information Technology,Chengdu 610225;Heavy Rain and Drought-Flood Disasters in Plateau and Basin Key Laboratory of Sichuan Province,Institute of Plateau Meteorology,China Meteorological Administration,Chengdu 610072;Beijing Meteorological Observatory,Beijing 100089)

机构地区：[1]四川省气候中心,成都610072 [2]高原大气与环境四川省重点实验室,成都610225 [3]成都信息工程大学,成都610225 [4]中国气象局成都高原气象研究所高原与盆地暴雨旱涝灾害四川省重点实验室,成都610072 [5]北京市气象台,北京100089

出　　处：《大气科学》2023年第5期1626-1640,共15页Chinese Journal of Atmospheric Sciences

基　　金：四川省重点研发项目2021YFS0282、2023YFS0376;四川省自然科学基金项目2022NSFSC0230;高原大气与环境四川省重点实验室开放课题PAEKL-2022-K06;高原与盆地暴雨旱涝灾害四川省重点实验室科技发展基金项目SCQXKJQN202215;中国气象局西南地区业务能力提升攻关团队。

摘　　要：本文利用NCEP/NCAR、ECMWF大气环流资料以及四川盆地101站气象站点资料等,通过线性相关分析、合成分析等统计方法,分析了冬季四川盆地霾天气气候特征及其对应的关键环流系统和对前期青藏高原热力作用的响应。结果表明:冬季四川盆地季霾日数呈弱增加趋势;四川盆地三大城市群为冬季霾多发区。影响冬季四川盆地霾天气的关键环流系统是高低空正压结构的高度场正距平、异常下沉运动以及异常偏弱的西伯利亚高压;影响霾天气的关键环境条件为偏西北风异常控制、稳定大气层结易于建立、边界层高度偏低且相对湿度偏低。前期11月青藏高原关键区热力作用是影响冬季四川盆地霾天气频发的重要外强迫因子。当前期11月高原关键区热源指数偏低时,冬季阿留申低压及西伯利亚高压显著偏弱,自北大西洋到西北太平洋存在一个类似于南支槽波列系统的弓形波列,青藏高原—四川盆地为正位势高度场距平控制,盆地上空为反气旋环流控制,配合异常的下沉气流,从而有利于霾的形成。青藏高原大气热源的异常及其耦合的四川盆地霾日数异常都可能是上游波列,尤其是中纬度北大西洋的扰动传播的结果,并受到青藏高原“背风坡”东侧下沉气流影响,导致霾日数偏多。Based on the reanalysis data provided by the National Centers for Environmental Prediction/National Center for Atmospheric Research,European Centre for Medium-Range Weather Forecasts,and Sichuan meteorological stations,the climatic characteristics of haze weather over the Sichuan Basin in winter,its corresponding key circulation system,and its response to the thermal action of the Tibet Plateau in the early stage were analyzed through linear correlation and synthetic analyses.The findings showed that the increase in the number of seasonal haze days in the Sichuan Basin is negligible,and the three major urban agglomerations in the Sichuan Basin are prone to haze in winter.During the haze days in the Sichuan Basin in winter,the critical circulation systems are positive anomalies of geopotential heights at 850,500,and 200 hPa;abnormal subsidence movement;and abnormally weak Siberian high.Under such circumstances,the lower troposphere over the Sichuan Basin is dominated by anomalous northwest winds,in situ stable stratification can be easily set up,boundary layer height is lower than normal,and surface relative humidity is reduced.The thermal effect in the key areas of the Tibet Plateau in early November is an important external forcing factor that affects the frequent occurrence of haze weather during winter in the Sichuan Basin.During the winter of low–heat index years in the key areas of the plateau in early November,the Aleutian Low and Siberian High are significantly weak;there is a bow wave train similar to the South Branch Trough wave train system from the North Atlantic to the Northwest Pacific.Further,the Tibet Plateau is characterized by significant positive geopotential height anomaly,and the Sichuan Basin is characterized by anticyclone circulation combined with an abnormal downdraft,which is conducive to haze formation.The atmospheric heat source anomaly over the Tibet Plateau and the haze day anomaly in the Sichuan Basin may result from the propagation of disturbances in the upstream wave train,especi

关 键 词：四川盆地 霾日 青藏高原 大气热源 

分 类 号：P461[天文地球—大气科学及气象学]