热带低频振荡影响中国东部冬季降水的机理  

Mechanism responsible for the impact of Madden-Julian Oscillation on the wintertime rainfall over eastern China

作　　者：刘冬晴[1] 杨修群[1] 

机构地区：[1]南京大学大气科学学院,南京210093

出　　处：《气象科学》2010年第5期684-693,共10页Journal of the Meteorological Sciences

基　　金：公益性行业(气象)科研专项(GYHY200806004;GYHY200706005);国家自然科学基金资助项目(40730953)

摘　　要：利用1979—2007年中国站点逐日降水记录、NCEP/NCAR大气再分析资料以及OLR资料等,分析了冬季热带低频振荡(MJO)与中国东部降水的关系及其伴随的大气环流扰动型,利用线性化全球大气环流模式模拟了大气对热带对流热源的响应,揭示了MJO影响中国东部冬季降水的机理。结果表明:热带对流活动从赤道印度洋西部东移至赤道西太平洋,中国东部冬季降水先后经历了长江流域多雨、整个南方多雨、华南多雨而长江流域少雨,这个过程大约经历了20 d左右时间。作为对东移性赤道热源的Rossby波型响应,当对流热源中心位于赤道印度洋中西部时,赤道以北地区的热源西部气旋式环流和热源东部反气旋式环流共同形成的西南气流扰动主要影响到中国长江流域,并造成那里多雨;而当对流热源中心东移到赤道印度洋东部时,西南气流扰动主要影响到中国华南地区,并造成那里多雨。This study firstly investigates the relationship between the Madden-Julian Oscillation（MJO） and the wintertime rainfall over eastern China and the associated atmospheric perturbation pattern,based on daily rainfall station records in China,OLR data and NCEP/NCAR reanalysis dataset.Results reveal that accompanying the migration of the MJO-related tropical convection center from western equatorial Indian Ocean to western equatorial Pacific during winter,more rainfall belt in eastern China migrates accordingly from Yangtze River valley（central China） towards southern China,which takes roughly 20 d.Then,a linearized atmospheric general circulation model is used to simulate atmospheric response to the MJO-related heating in order to understand the mechanism responsible for the MJO＇s impact.The response is basically characterized by the Gill-type structure in the tropics,with a pairs of cyclonic circulations symmetric about the equator in the western part of heat source and a pairs of anti-cyclonic circulations in the eastern part of heat source.This response generates southwesterly perturbation and more rainfall over Yangtze River valley（central China） when the MJO-related convection center locates over central-to-western equatorial Indian Ocean,while the MJO-related convection center locates over eastern equatorial Indian Ocean,there is more rainfall over southern China.

关 键 词：低频振荡 对流活动 冬季降水 

分 类 号：P434.4[天文地球—大气科学及气象学]