Indices of El Nio and El Nio Modoki:An Improved El Nio Modoki Index

作     者：李根 任保华 杨成昀 郑建秋 LI Gen;REN Baohua;YANG Chengyun;ZHENG Jianqiu

作者机构：School of Earth and Space Sciences University of Science and Technology of China 

出 版 物：《Advances in Atmospheric Sciences》 (大气科学进展（英文版）)

年 卷 期：2010年第27卷第5期

页      面：1210-1220页

核心收录：

学科分类：080904[工学-电磁场与微波技术] 0810[工学-信息与通信工程] 07[理学] 0809[工学-电子科学与技术（可授工学、理学学位）] 070601[理学-气象学] 08[工学] 080402[工学-测试计量技术及仪器] 0804[工学-仪器科学与技术] 0706[理学-大气科学] 081001[工学-通信与信息系统] 

基　　金：supported by the National Natural Science Foun-dation of China (Grant Nos. 40675028 and 40975029) the National Basic Research Program of China (Grant No.2006CB403600) the State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics (LASG) 

主　　题：El Nino El Nino Modoki NINO3 index improved El Nino Modoki index (IEMI) 

摘      要：In recent years, El Nino Modoki （a type of pseudo-El Nino） has been distinguished as a unique large-scale ocean warming phenomenon happening in the central tropical Pacific that is quite different from the traditional El Nino. In this study, EOF analysis was used to successfully separate El Nino and El Nino Modoki. The abilities of the NINO3 index, NINO3.4 index, NINO1＋2 index and NINO4 index in characterizing El Nino were explored in detail. The resulting suggestion was that, comparatively, NINO3 is the optimal index for monitoring El Nino among the four NINO indices, as the other NINO indices were found to be less good at distinguishing between El Nino and El Nino Modoki signals, or were easily disturbed by El Nino Modoki signals. Further, an improved El Nino Modoki index （IEMI） was introduced in the current paper to better represent the El Nino Modoki that is captured by the second leading EOF mode of monthly tropical Pacific sea surface temperature anomalies （SSTAs）. The IEMI is an improvement of the El Nino Modoki index （EMI） through adjustments made to the inappropriate weight coefficients of the three boxes of EMI. The IEMI therefore overcomes the EMI’s inability to monitor the two historical El Nino Modoki events, as well as avoids the possible risk （present in the EMI） of excluding the interference of the El Nino signal. The realistic and potential advantages of the IEMI are clear.