亚洲热带夏季风指数与中国南方降水的关系  

The relationship between Asian tropical summer monsoon index and precipitation in southern China

作　　者：任菊章[1] 琚建华[1] 米瑞芝 段长春[1] 陶云[1] REN Juzhang;JU Jianhua;MI Ruizhi;DUAN Changchun;TAO Yun(Yunnan Institute of Meteorological Science,Kunming 650034,China;Yunnan Meteorological Observatory,Kunming,650034,China)

机构地区：[1]云南省气象科学研究所,昆明650034 [2]云南省气象台,昆明650034

出　　处：《气象科学》2021年第2期228-236,共9页Journal of the Meteorological Sciences

基　　金：国家自然科学基金资助项目(41565002,41365007);中国气象科学研究院基本科研业务费专项(2016Z002)。

摘　　要：利用1979—2013年夏季全球2.5°×2.5°逐日环流资料和中国气象站点降水观测资料,采用动力学因子(西南风)与热力学因子(Radiation Longwave covting,OLR)相结合定义了标准化的亚洲热带夏季风指数(Tropical Summer Monsoon Index,TSMI)。结果表明,该指数能够很好地描述亚洲热带夏季风的年际变化和准4 a变化特征,并能够指示中国南方夏季降水的异常变化和东亚大气环流特征。强(弱)亚洲热带夏季风年,印度夏季风槽和南海夏季风槽加强加深(减弱),孟加拉湾海域一致西南风(东风)异常,越赤道急流向北输送偏强(偏弱),南海季风槽位置偏西(东),南海区域一致西南风异常,西太平洋副热带高压和南亚高压纬向位置分离(重叠),低层气流在长江流域辐散(辐合),华南地区辐合(辐散),长江中下游流域出现异常下沉(上升)运动,造成长江流域降水偏少(偏多),华南地区降水比常年偏多(偏少)。Based on the NCEP/NCAR global reanalysis daily data and precipitation data from Chinese meteorological stations during 1979 to 2013,a new Asian Tropical Summer Monsoon Index(TSMI)was defined by combining the dynamic factor(southwest wind)and the thermodynamic factor(OLR).Results show that the index can well describe the inter-annual variation of the summer monsoon,as well as the abnormal change of summer precipitation in southern China and the characteristics of eastern Asian atmospheric circulation.In stronger(weaker)monsoon years,the Indian summer monsoon trough and the South China Sea summer monsoon trough deepen(weaken),so the southwesterly(easterly)wind anomaly control the bay of Bengal area,meanwhile,cross-equatorial flow moves north strongly(weakly),the South China Sea monsoon trough closes to the west Pacific(Indo-China Peninsula),and the westerly anomaly is in the south part of the South China Sea area,while the easterly anomaly is in the north part.Another characteristics of the circulation abnormal are the separated(overlapping)pattern between the ridge of West Pacific subtropical high and the South Asia high.These abnormal makes low-level wind diverge(converge)in Yangtze Valley,converge(diverge)in southern China.So there exist clear downdraft motion(ascending motion)over the middle and lower reaches of the Yangtze River,which leads to less(more)in middle and lower reaches of the Yangtze River and is more(less)precipitationin southern China.

关 键 词：亚洲热带夏季风 中国南方 降水 大气环流 

分 类 号：P426.61[天文地球—大气科学及气象学]