东亚-太平洋地区环流场和热力场由冬向夏转换的过程特征及其可能机制  

Features of Transformation on Circulation and Thermal Fields over East Asia-Pacific Regions from Winter to Summer and Its Possible Mechanism

作　　者：池艳珍[1,2] 刘丹妮[1,3] 何金海[1] 祁莉[1] 

机构地区：[1]南京信息工程大学气象灾害省部共建教育部重点实验室,江苏南京210044 [2]福建省气候中心,福建福州350001 [3]浙江省气象服务中心,浙江杭州310017

出　　处：《高原气象》2013年第4期983-992,共10页Plateau Meteorology

基　　金：国家自然科学基金项目(41075068);973项目(2013CB430202);长江学者和创新团队发展计划项目;江苏高校优势学科建设工程项目

摘　　要：利用NCEP/NCAR逐日再分析资料和青藏高原逐日视热源资料,分析了东亚-太平洋地区对流层热力场和环流场的季节特征。结果表明,东亚-太平洋热力场上呈现出冬、夏半年反向的特征,冬半年热力格局为"西冷东暖",夏半年则转为"西暖东冷",冬半年向夏半年的过渡发生在3月底4月初,相应地,我国东部上空视热源也从冷却转为加热。热力场季节转换的同时,对流层各层环流形势也发生了调整:低层大陆冷高压减弱、东移,太平洋副热带高压显著西伸,形成东亚-西太平洋35°N以南一致的南风区;中层西风带发生了长波调整,由冬季"三槽型"向夏季"四槽型"过渡,西风急流减弱、北移;高层反气旋中心更替,我国上空偏南风由偏北风替代。环流的演变自低层向高层推进,下垫面感热加热的季节变化引起了低层环流的调整以及上升运动的发展,与上升运动相伴的凝结潜热释放则增强了东亚上空的热源,进一步加强了"西暖东冷"的热力格局,从而推进中高层环流的演变。环流调整的时间与东亚副热带季风雨带建立的时间一致,因此,由热力场季节变化引起的对流层环流形势的调整可看成是东亚副热带夏季风环流型的建立过程。Based on NCEP/NCAR reanalysis data and apparent heat source data,the seasonal transition characteristics on circulation and thermal field in troposphere were analyzed.The results show that both the transformations on circulation and thermal fields from winter to summer take place during late March to early April.The west cooling-east heating pattern on thermal field during winter turns to reverse during summer.Simultaneously,the transitions of circulation patterns can be summarized as follows： The continental cold high at low level moves eastward and decreased rapidly,while the southerly enhanced around South China.The reduction and northward of westerly jet caused by long-wave adjustment over middle-high latitude is a signal of seasonal transition at middle layer.The anticyclone center＇s breakdown and rebuild leads to the prevailing of northerly instead of southerly at the high level.The transformation of circulation triggers the ascending motion,which associated with the latent heating enforced the heat source over East Asia.The transitions on circulation and thermal fields correspond with the rain belt in late March suggest the establishment of East Asia Subtropical Monsoon.

关 键 词：热力场 环流场 季节变化 东亚副热带夏季风 

分 类 号：P466[天文地球—大气科学及气象学]