Different impacts of various El Niño events on the Indian Ocean Dipole
Different impacts of various El Niño events on the Indian Ocean Dipole
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DOI：
10.1007/s00382-013-1711-2
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发表时间：
2013-12
期刊：
影响因子：
4.6
通讯作者：
Xin Wang;Chunzai Wang
中科院分区：
文献类型：
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作者：
Xin Wang;Chunzai Wang
我们的早期工作（Wang and Wang in J Clim 26:1322–1338, 2013）将厄尔尼诺Modoki事件分为厄尔尼诺Modoki I和II，因为它们对中国南方的降雨和台风登陆活动表现出不同的影响。厄尔尼诺Modoki I和II的暖海温异常分别起源于赤道中太平洋和副热带东北太平洋。厄尔尼诺Modoki I呈现出围绕赤道对称的海温异常分布，其中赤道中太平洋升温幅度最大；而El Niño Modoki II呈现出非对称分布，暖海温异常从东北太平洋延伸至赤道中太平洋。本文研究了不同类型的厄尔尼诺事件对印度洋偶极子（IOD）的影响。与典型的厄尔尼诺现象类似，厄尔尼诺Modoki I与印度太平洋地区沃克环流减弱有关，导致热带印度洋东部和海洋大陆降水减少，从而导致爪哇-苏门答腊岛表面东风异常。在比耶克内斯反馈下，东风异常诱发爪哇-苏门答腊岛外海出现冷海温异常，典型厄尔尼诺和厄尔尼诺莫多基Ⅰ期印度洋容易出现正IOD。而厄尔尼诺莫多基Ⅰ期厄尔尼诺莫多基期对沃克环流产生相反影响，导致爪哇-苏门答腊岛降水增多和地表西风异常。因此，厄尔尼诺Modoki II 在Bjerknes 反馈框架下有利于负IOD 的发生和发展。
Our early work (Wang and Wang in J Clim 26:1322–1338, 2013) separates El Niño Modoki events into El Niño Modoki I and II because they show different impacts on rainfall in southern China and typhoon landfall activity. The warm SST anomalies originate in the equatorial central Pacific and subtropical northeastern Pacific for El Niño Modoki I and II, respectively. El Niño Modoki I features a symmetric SST anomaly distribution about the equator with the maximum warming in the equatorial central Pacific, whereas El Niño Modoki II shows an asymmetric distribution with the warm SST anomalies extending from the northeastern Pacific to the equatorial central Pacific. The present paper investigates the influence of the various groups of El Niño events on the Indian Ocean Dipole (IOD). Similar to canonical El Niño, El Niño Modoki I is associated with a weakening of the Walker circulation in the Indo-Pacific region which decreases precipitation in the eastern tropical Indian Ocean and maritime continent and thus results in the surface easterly wind anomalies off Java-Sumatra. Under the Bjerknes feedback, the easterly wind anomalies induce cold SST anomalies off Java- Sumatra, and thus a positive IOD tends to occur in the Indian Ocean during canonical El Niño and El Niño Modoki I. However, El Niño Modoki II has an opposite impact on the Walker circulation, resulting in more precipitation and surface westerly wind anomalies off Java-Sumatra. Thus, El Niño Modoki II is favorable for the onset and development of a negative IOD on the frame of the Bjerknes feedback.