El Nino Modoki and its possible teleconnection
El Nino Modoki and its possible teleconnection
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DOI：
10.1029/2006jc003798
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发表时间：
2007-11-08
影响因子：
3.6
通讯作者：
Yamagata, Toshio
中科院分区：
文献类型：
--
作者：
Ashok, Karumuri;Behera, Swadhin K.;Yamagata, Toshio
利用1979 - 2005年的观测资料，我们发现赤道中太平洋发生了不同于常规厄尔尼诺事件的异常增暖事件。这种独特的变暖在赤道太平洋中部与马蹄形模式，两侧是一个较冷的海表温度异常（SSTA）的沿着赤道两侧。对热带太平洋海温月变化的经验正交函数分析表明，这些事件由第二模态表示，解释了12%的方差。由于大多数这样的事件不是厄尔尼诺演变的一部分，这种现象被命名为厄尔尼诺Modoki（伪厄尔尼诺）（“Modoki”是一个经典的日语单词，意思是“类似但不同的事情”）。El Nino Modoki涉及海洋-大气耦合过程，在演变过程中包括独特的三极海平面压力模式，类似于El Nino的南方涛动。因此，整个实体被命名为厄尔尼诺-南方涛动（ENSO）Modoki。ENSO Modoki事件对地球仪许多地区的温度和降水有显著影响。根据季节的不同，对包括日本在内的远东、新西兰、美国西海岸等地区的影响，与常规ENSO相反。1979 - 2004年和1958 - 1978年两个时期的各种海洋/大气变量之间的差异图表明，最近赤道东风减弱有关减弱的纬向海面温度梯度导致更多的温跃层变平。这似乎是近几十年来ENSO Modoki事件更频繁和持续发生的原因。
Using observed data sets mainly for the period 1979 - 2005, we find that anomalous warming events different from conventional El Nino events occur in the central equatorial Pacific. This unique warming in the central equatorial Pacific associated with a horseshoe pattern is flanked by a colder sea surface temperature anomaly ( SSTA) on both sides along the equator. empirical orthogonal function ( EOF) analysis of monthly tropical Pacific SSTA shows that these events are represented by the second mode that explains 12% of the variance. Since a majority of such events are not part of El Nino evolution, the phenomenon is named as El Nino Modoki ( pseudo-El Nino) ("Modoki" is a classical Japanese word, which means "a similar but different thing"). The El Nino Modoki involves ocean-atmosphere coupled processes which include a unique tripolar sea level pressure pattern during the evolution, analogous to the Southern Oscillation in the case of El Nino. Hence the total entity is named as El Nino-Southern Oscillation (ENSO) Modoki. The ENSO Modoki events significantly influence the temperature and precipitation over many parts of the globe. Depending on the season, the impacts over regions such as the Far East including Japan, New Zealand, western coast of United States, etc., are opposite to those of the conventional ENSO. The difference maps between the two periods of 1979 - 2004 and 1958 - 1978 for various oceanic/atmospheric variables suggest that the recent weakening of equatorial easterlies related to weakened zonal sea surface temperature gradient led to more flattening of the thermocline. This appears to be a cause of more frequent and persistent occurrence of the ENSO Modoki event during recent decades.