三类厄尔尼诺事件对东亚大气环流及中国东部次年夏季降水的影响

利用全球海表温度(SST)资料、ONI(Oceanic Nino Index)序列以及中国160站逐月降水资料,研究了不同类型El Nino事件的主要特征及其对东亚大气环流及中国东部次年夏季逐月及季节降水的影响。结果表明:1)据El Nino事件期间SST最大正异常所在区域,将El Nino事件分为Nino3、Nino4和Nino3.4型。2)El Nino事件次年6月,Nino3型时降水显著正异常区主要位于鄱阳湖和洞庭湖流域,Nino4型时位于鄱阳湖流域、桂粤湘三省交界及广西西部,Nino3.4型时位于洞庭湖流域。7月Nino3型降水显著正异常区北移至长江流域,8月则呈西多东少反相分布。从次年6月至8月,Nino4型降水显著正异常区逐渐北移,Nino3.4型降水显著正异常区则从南到北再移向东北。3)在整个次年夏季,Nino3、Nino4和Nino3.4型降水显著正异常区在中国东部呈自南向北分布。无论逐月或季节降水,均是Nino4型降水正异常最强、Nino3.4型最弱。4)不同类型事件次年夏季和各月环流特征存在一定差异,总体而言,对于南亚高压,Nino3型、Nino4型事件后呈偏强、东伸和北抬的特点,且后者较前者时更强;Nino3.4型事件后主要呈减弱、西退特征。对于西太平洋副热带高压,Nino3型、Nino4型事件后主要呈偏强、西伸、北抬特征,后者较前者更强,西伸、北抬也更明显;Nino3.4型后,副高以东撤、北抬特征为主。

Effects of three types of El Nino events on atmospheric circulation over East Asia and following summer precipitation in eastern China

Using the global monthly mean sea surface temperature(SST) data,the ONI(Oceanic Nino Index) series,and the monthly rainfall of 160 stations in China,El Nino events are classified in several ways,and the influences of all kinds of El Nino events on East Asia circulation and the monthly and seasonal precipitation in following summer in eastern China are investigated.Results indicate that:1)According to the regions of biggest positive SST anomaly during El Nino events,El Nino events are categorized into three patterns,namely,the Nino3,Nino4 and Nino3.4 patterns.2)In the following June of El Nino event year,the significant positive precipitation anomaly mainly locates in the Poyang Lake and Dongting Lake basins for the Nino3 pattern,the Poyang Lake basin,the junction of Guangxi,Guangdong and Hunan,and the western of Guangxi for the Nino4 pattern,and the Dongting Lake basin for the Nino3.4 pattern,respectively.From June to July,the positive precipitation anomaly moves northward into the Yangtze River basin for the Nino3 pattern.The precipitation anomaly shows reverse phase distribution from west(more) to east(less) in August.From June to August,the positive precipitation anomaly gradually moves northward for Nino4 pattern,while does from south to north then northeastward for Nino3.4 pattern.3)In the whole following summer,the significant positive precipitation anomaly of Nino3,Nino4 and Nino3.4 patterns distributes from south to north in eastern China.The positive precipitation anomaly is the strongest for Nino4 pattern and the weakest for Nino3.4 pattern,no matter in June,July,August or summer.4)The different types of El Nino events are corresponding to different circulation characteristics in the following June,July,August or summer.On the whole,the South Asia high becomes stronger and moves eastward and northward corresponding to the climatological field after the events of Nino3 and Nino4 patterns,and it is stronger for Nino3 than that for Nino4.After the event of Nino3.4 pattern,it is weaker and withdraw westward.The western Pacific subtropical high is stronger and moves westward and northward corresponding to the climatological field after the events of Nino3 and Nino4 patterns,and it is stronger moves more westward and northward for Nino3 than that for Nino4.After the event of Nino3.4 pattern,it retreats eastward and moves northward.