夏季南亚高压东-西振荡过程中青藏高原及周边上对流层水汽的分布和传输特征  

Distribution and Transport of the Upper Tropospheric Water Vapor over the Tibetan Plateau Area during the East-West Oscillation of the South Asia High in Summer

作　　者：唐南军 任荣彩[1,3] 祝传栋 吴国雄[1,5] TANG Nanjun;REN Rongcai;ZHU Chuandong;WU Guoxiong(State Key Laboratory of Numerical Modeling of Atmospheric Sciences and Geophysical Fluid Dynamics,Institute of Atmospheric Physics,Chinese Academy of Sciences,Beijing 100029;Fujian Key Laboratory of Severe Weather,Fuzhou 350008;Collaborative Innovation Center on Forecast and Evaluation of Metrological Disasters(CIC-FEMD),Nanjing University of Information Science&Technology,Nanjing 210044;Hubei Meteorological Service Center,Wuhan 430205;University of Chinese Academy of Sciences,Beijing 100049;Fujian Provincial Meteorological Observatory,Fuzhou 350008)

机构地区：[1]中国科学院大气物理研究所大气科学和地球流体力学数值模拟国家重点实验室,北京100029 [2]福建省灾害天气重点实验室,福州350008 [3]南京信息工程大学气象灾害预报预警与评估协同创新中心,南京210044 [4]湖北省气象服务中心,武汉430205 [5]中国科学院大学,北京100049 [6]福建省气象台,福州350008

出　　处：《大气科学》2024年第3期967-986,共20页Chinese Journal of Atmospheric Sciences

基　　金：国家自然科学基金项目91837311、42075052、42105039;福建省气象局海洋气象灾害机理与预报技术重点创新团队。

摘　　要：夏季南亚高压的“双模态”分布对应着其中心位置在10~20天准双周时间尺度上的东—西振荡,对青藏高原及周边上对流层的水汽分布和传输有显著影响。本文利用夏季7~8月逐日的ERAI再分析资料,通过基于南亚高压东—西振荡指数的位相合成分析发现,当南亚高压呈青藏高原模态时,青藏高原(伊朗高原)地区上对流层水汽含量异常偏高(低),伊朗高原模态时则相反;伴随南亚高压中心位置由青藏高原向西移至伊朗高原上空,上对流层水汽含量正异常中心亦自青藏高原东侧向西逐渐传播到伊朗高原以西地区。进一步诊断表明,除了在青藏高原北侧和南侧水汽经向绝热输送异常有抵消作用外,两高原地区上对流层水汽倾向异常主要由水汽纬向绝热输送异常及其辐合辐散异常所贡献,而青藏高原地区对流活动引起的垂直非绝热输送异常在上对流层则主要与剩余项(水汽的凝结和蒸发)相抵消。因此,青藏高原(伊朗高原)上对流层为水汽含量正异常时对应着青藏高原上空的对流活动异常偏弱(强)。而南亚高压中心位置和上对流层水汽含量正异常中心自青藏高原向伊朗高原移动的过程,对应着青藏高原地区的对流活动异常和垂直向上的水汽非绝热输送异常不断增强,同时上对流层水汽凝结异常也不断增强。此外,南亚高压向西移动过程中,上对流层水汽绝热辐合(辐散)异常主要发生在其西(东)侧,这是造成水汽含量异常中心纬向传播的主要原因。The bimodal distribution of the South Asia high(SAH)corresponds to the east–west oscillation of its center locations on a quasi-biweekly timescale of 10–20 days during summer,significantly influencing the water vapor distribution and upper troposphere transport over the Tibetan Plateau(TP)area.In this study,we used the daily-averaged European Centre for Medium-Range Weather Forecasts Interim Re-Analysis(ERAI)datasets and phases composited analysis method based on the east–west oscillation indexes of the SAH in July–August.The results indicated that,for the TP mode of the SAH,the water vapor content is abnormally high(low)in the upper troposphere over the TP(IP,Iranian Plateau).However,the opposite is true over the TP and IP respective,for the IP mode of the SAH.In association with the centers of the SAH moving westward from the TP to the IP,the positive anomaly corresponding to the water vapor content in the upper troposphere gradually propagates westward from the eastern TP to the west of the IP.Furthermore,in the upper troposphere,except where the abnormal meridional adiabatic transport has a counteracting effect on the northern and southern TP,the water vapor tendency anomalies over the two plateaus are primarily driven by the abnormal zonal adiabatic water vapor transport as well as their convergence and divergence anomalies.However,the abnormal upward diabatic water vapor transport due to convection over the TP is counteracted by the residual term(water vapor condensation and evaporation).Therefore,when the water vapor content anomaly is positive in the upper troposphere over the TP(IP),an abnormally weak(strong)convective occurs.Corresponding to the center locations of the SAH and centers of the positive anomaly of the water vapor content in the upper troposphere as it moves from the TP to the IP,the abnormal convection and upward diabatic water vapor transport continue to increase over the TP.Meanwhile,the water vapor condensation anomaly in the upper troposphere increased steadily.Furthermore,as t

关 键 词：南亚高压东—西振荡 青藏高原周边 上对流层水汽 分布与传输 

分 类 号：P434[天文地球—大气科学及气象学]