A New Approach for Classifying Two Types of El Nio Events

作     者：LI Shuanglin WANG Qin 

作者机构：Nansen-Zhu International Research Centre and Climate Change Research Center Institute of Atmospheric Physics Chinese Acad-. emy of Sciences Beijing 100029 China Chengdu University of lnformation Technology Chengdu 610225 China 

出 版 物：《Atmospheric and Oceanic Science Letters》 (大气和海洋科学快报（英文版）)

年 卷 期：2012年第5卷第5期

页      面：414-419页

学科分类：12[管理学] 1201[管理学-管理科学与工程(可授管理学、工学学位)] 07[理学] 070601[理学-气象学] 0706[理学-大气科学] 

基　　金：supported by the Nationa Basic Research Program of China  "Oceanic circulation  structure characteristics  variation mechanisms  and climate effects of thewarm pool in the tropical Pacific"  under Grant 2012CB417403 

主　　题：分类方法 类型 事件 太平洋海温 热带太平洋 El 表层海水温度 经验正交函数 

摘      要：In recent decades, the typical El Nio events with the warmest SSTs in the tropical eastern Pacific have become less common, and a different of El Nio with the warmest SSTs in the central Pacific, which is flanked on the east and west by cooler SSTs, has become more fre-quent. The more recent type of El Nio was referred to as central Pacific El Nio, warm pool El Nio, or dateline El Nio, or the El Nio Modoki. Central Pacific El Nio links to a different tropical-to-extratropical teleconnection and exerts different impacts on climate, and several classification approaches have been proposed. In this study, a new classification approach is proposed, which is based on the linear combination (sum or difference) of the two leading Empirical Orthogonal Functions (EOFs) of tropical Pacific Ocean sea surface temperature anomaly (SSTA), and the typical El Ni o index (TENI) and the central El Nio index (CENI) are able to be derived by projecting the observed SSTA onto these combinations. This classification not only reflects the characteristics of non-orthogonality between the two types of events but also yields one period peaking at approximate two to seven years. In particular, this classification can distin-guish the different impacts of the two types of events on rainfall in the following summer in East China. The typical El Nio events tend to induce intensified rainfall in the Yangtze River valley, whereas the central Pacific El Nio tends to induce intensified rainfall in the Huaihe River valley. Thus, the present approach may be appropriate for studying the impact of different types of El Nio on the East Asian climate.