夏季南海低空越赤道气流变化与亚澳季风区降水异常的联系  

Contact between precipitation anomaly in Asian-Australian monsoon region and low-level cross-equatorial flow variation over South China Sea in summer

作　　者：范倩莹 李忠贤[1] 王健治 FAN Qianying;LI Zhongxian;WANG Jianzhi(Key Laboratory of Meteorological Disaster,Ministry of Education(KLME)/Joint International Research Laboratory of Climate and Environment Change(ILCEC)/Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters(CIC-FEMD),Nanjing University of Information Science&Technology,Nanjing 210044,China;Meteorological Observatory of Xiamen Air Traffic Management Bureau,Civil Aviation Administration of China,Xiamen 361006,China)

机构地区：[1]南京信息工程大学气象灾害教育部重点实验室/气候与环境变化国际联合实验室/气象灾害预报预警与评估协同创新中心,江苏南京210044 [2]中国民用航空局厦门空中交通管理站气象台,福建厦门361006

出　　处：《大气科学学报》2018年第5期684-691,共8页Transactions of Atmospheric Sciences

基　　金：国家自然科学基金资助项目(41575102)

摘　　要：基于1979—2014年ERA-Interim逐月风场和水汽通量资料及GPCP逐月降水率资料,采用相关分析及合成分析等方法研究了夏季南海低空越赤道气流的变化特征及其与亚澳季风区降水异常的联系。结果表明:1)夏季南海低空越赤道气流强度的年际变化特征明显,具有3~4 a的周期。2)夏季南海低空越赤道气流强度变化与热带东印度洋和海洋性大陆区域降水异常具有显著的负相关关系、与热带西太平洋降水异常存在明显的正相关关系、与我国中部地区降水异常存在较好的负相关关系。3)当夏季南海低空越赤道气流强度偏强时,850 hPa上自阿拉伯海向东一直延伸到热带西太平洋为西风异常,这种环流形势有利于热带西太平洋出现水汽辐合,使得该区域降水出现明显偏多,同时热带东印度洋低层为东风异常,受其影响,热带东印度洋和海洋性大陆区域出现水汽辐散,使得该区域降水偏少;此外,在我国东南沿海为一个气旋式风场异常,不利于来自热带海洋的水汽输送到达我国中部地区,使得该地区降水偏少;反之亦然。4)当夏季南海低空越赤道气流偏强时,东亚地区局地Hadley环流表现为异常偏弱,低空偏南越赤道气流异常在20°N附近与来自北半球的冷空气交汇上升,赤道附近及30~40°N地区出现异常下沉运动,使得热带海洋性大陆区域和我国中部地区降水减少;反之亦然。The cross-equatorial flow(CEF)plays an important role in the momentum,mass and water vapor exchange between the northern and southern hemispheres.It is one of important factors that reflect and affect the weather and climate anomalies in the northern and southern hemispheres,and especially has close connections with Asian monsoon,summer precipitation and typhoons.In recent years,the extensive research on the CEF has been conducted by domestic and foreign researchers.Previous studies have focused on the impact of CEF over the South China Sea(SCS)on Asian summer monsoon,especially on East Asian summer monsoon and South China Sea summer monsoon.However,there are few studies on the characteristics of SCS low-level CEF(SCEF)and the connection between SCEF variation and precipitation anomalies in the Asian-Australian monsoon region.Therefore,according to the latest released Interim reanalysis data by ECMWF and the precipitation rate data by GPCP during 1979-2014,this paper analyzes the spatial structure and temporal variation of summer SCEF by using the correlation analysis and synthesis analysis methods.It discusses the relationship between SCEF and precipitation anomalies in the Asian-Australian monsoon region,and further presents the possible physical process of influence of SCEF variation on precipitation anomalies in the Asian-Australian monsoon region by analyzing characteristics of atmospheric circulation,water vapor transport and local Hadley circulation.Results show that the intensity of SCEF has a significant interannual variation in summer,with a 3-4 yr period.The intensity of SCEF in summer shows significant negative(positive)correlations with precipitation anomalies in the tropical eastern Indian Ocean and the maritime continent(the tropical western Pacific).In addition,the intensity of SCEF has a clearly negative correlation with precipitation anomalies in central China in summer.When the intensity of SCEF is stronger in summer,there are westerly wind anomalies from the Arabia Sea to the tropical western

关 键 词：南海越赤道气流 降水 大气环流 夏季 

分 类 号：P732[天文地球—海洋科学] P426.6