Observations revealed notable discrepancies in the 2023/24 El Niño compared to earlier events, despite registering moderate Niño3.4 index magnitudes. Essential indicators such as the westerly wind burst, thermocline zonal tilting, and eastward propagation of oceanic Kelvin waves were conspicuously weak, indicating a weak air-sea coupled in contrast to past occurrences, the 2023/24 El Niño coincided with unusually high North Atlantic Tripole and extratropical North Pacific sea surface temperatures (SSTs). The elevated North Atlantic Tripole SST triggered a strong negative Pacific meridional mode and easterly anomalies in the equatorial western-central Pacific. At the same time, the extratropical North Pacific SST induced a negative Pacific Decadal Oscillation-like pattern. These anomalies potentially dampened SST-wind coupling during the developmental stages of El Niño. The negative Pacific meridional mode distinguished the 2023/24 El Niño from previous events and substantially altered its local and remote influences.

中文翻译：

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北大西洋三极子和温带北太平洋极端海温对 2023/24 年厄尔尼诺现象的影响


观测显示，尽管 2023/24 年的厄尔尼诺指数幅度适中，但与早期事件相比，2023/24 年的厄尔尼诺现象存在显着差异。西风爆发、温跃层纬向倾斜和海洋开尔文波东向传播等基本指标明显较弱，表明气海耦合较弱与 2023/24 年厄尔尼诺现象相比，2023/24 年厄尔尼诺现象恰逢北大西洋三极和温带北太平洋海面温度 （SST） 异常高。升高的北大西洋三极子海温在赤道中西太平洋引发了强烈的负太平洋经向模态和偏东距平。同时，温带北太平洋 SST 诱导了负太平洋年代际振荡样型。这些异常可能在厄尔尼诺现象的发展阶段抑制了海温-风耦合。负太平洋经向模态将 2023/24 年厄尔尼诺现象与以前的事件区分开来，并显着改变了其局部和远程影响。