Exceptionally strong easterly wind burst stalling El Nino of 2014
Exceptionally strong easterly wind burst stalling El Nino of 2014
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DOI：
10.1073/pnas.1514182113
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发表时间：
2016-02-23
影响因子：
11.1
通讯作者：
Fedorov, Alexey V.
中科院分区：
文献类型：
--
作者：
Hu, Shineng;Fedorov, Alexey V.
热带太平洋的季节性风爆发被认为会影响厄尔尼诺事件的演变和多样性。特别是，2014年初发生的两次强西风爆发（WWBs）显然将海洋-大气系统推向了一个中等到强烈的厄尔尼诺现象——根据一些气候模式，这可能是一个极端事件。然而，这一事件的进展很快就停滞了，全年的变暖仍然非常微弱。研究发现，6月出现的异常强烈的全流域东风暴（EWB）是阻碍厄尔尼诺发展的关键因素。在这次EWB之后不久，所有主要的尼诺指数迅速下降到接近正常值；今年晚些时候才恢复了温和的增长。东风爆发和随后wbs的减弱导致赤道太平洋中部和东部两个独立的变暖中心持续存在，抑制了对厄尔尼诺至关重要的正比耶克尼斯反馈。用一个带有叠加风爆发的气候模型进行的实验支持了这些结论，指出厄尔尼诺现象的可预测性存在固有的局限性。此外，我们发现东风爆发的空间结构与观测到的热带太平洋风应力的年代际趋势相匹配，表明季节内风爆发与年代际气候变化之间存在潜在联系。
Intraseasonal wind bursts in the tropical Pacific are believed to affect the evolution and diversity of El Nino events. In particular, the occurrence of two strong westerly wind bursts (WWBs) in early 2014 apparently pushed the ocean-atmosphere system toward a moderate to strong El Nino-potentially an extreme event according to some climate models. However, the event's progression quickly stalled, and the warming remained very weak throughout the year. Here, we find that the occurrence of an unusually strong basin-wide easterly wind burst (EWB) in June was a key factor that impeded the El Nino development. It was shortly after this EWB that all major Nino indices fell rapidly to near-normal values; a modest growth resumed only later in the year. The easterly burst and the weakness of subsequent WWBs resulted in the persistence of two separate warming centers in the central and eastern equatorial Pacific, suppressing the positive Bjerknes feedback critical for El Nino. Experiments with a climate model with superimposed wind bursts support these conclusions, pointing to inherent limits in El Nino predictability. Furthermore, we show that the spatial structure of the easterly burst matches that of the observed decadal trend in wind stress in the tropical Pacific, suggesting potential links between intraseasonal wind bursts and decadal climate variations.