中国科学院海洋研究所Fan Jia与Wenju Cai等合作发现，从多年拉尼娜到强厄尔尼诺的转变很少见，但在全球变暖的情况下有所增加。相关论文于2024年12月25日发表在《科学通报》杂志上。

厄尔尼诺-南方涛动（ENSO）在温暖厄尔尼诺和寒冷拉尼娜之间，在振幅和时间演化上表现出强烈的不对称性。厄尔尼诺现象通常导致赤道太平洋的热量释放，有利于其迅速终止并过渡到拉尼娜现象，而拉尼娜现象持续存在并连续数年补给赤道太平洋，为随后的厄尔尼诺现象的发展做好了准备，如2020-2023年发生的情况。多年的热量补给是否会增加，向强厄尔尼诺转变的可能性仍不得而知。

研究人员表明这种转变是罕见的，但更有可能在短暂的温室变暖。在多年拉尼娜之后的北方春季和初夏，尽管西太平洋有大量补给，但赤道中部太平洋的温跃层仍然异常浅，海表温度（SST）仍然异常冷。寒冷的条件抑制了随后从温暖的西太平洋向东移动的大气深层对流，延迟了海洋-大气耦合的开始，因此厄尔尼诺现象的增长。在高排放情景下，这种转变仍然很少见，但可能性是前者的两倍多。预估的变化与气候纬向海温梯度的预估减弱（促进大气对流向东运动），和赤道太平洋上层海洋分层的预估增强（增强海洋-大气耦合）相一致。

这一结果提供了，对多年拉尼娜之后的厄尔尼诺现象的预测见解，并促进了我们对温室变暖下ENSO转变的理解。

附：英文原文

Title: Transition from multi-year La Nia to strong El Nio rare but increased under global warming

Author: Fan Jia a b, Wenju Cai b c d e

Issue&Volume: 2024/12/25

Abstract: El Nio-Southern Oscillation (ENSO) exhibits a strong asymmetry between warm El Nio and cold La Nia in amplitude and temporal evolution. An El Nio often leads to a heat discharge in the equatorial Pacific conducive to its rapid termination and transition to a La Nia, whereas a La Nia persists and recharges the equatorial Pacific for consecutive years preconditioning development of a subsequent El Nio, as occurred in 2020–2023. Whether the multiyear-long heat recharge increases the likelihood of a transition to a strong El Nio remains unknown. Here, we show that such a transition is rare but more likely under transient greenhouse warming. In boreal spring and early summer after a multiyear La Nia, despite a substantial recharge in the western Pacific, thermocline remains anomalously shallow and sea surface temperature (SST) remains anomalously cold in the equatorial central Pacific. The cold conditions inhibit an ensuing eastward movement of atmosphere deep convection out of the warm western Pacific, delaying onset of ocean-atmosphere coupling, and hence growth of an El Nio. Under a high emission scenario, such a transition is still rare but more than twice as likely. The projected change is consistent with a projected weakening in climatological zonal SST gradient that promotes the eastward movement of atmosphere convection and a projected intensification in upper-ocean stratification of the equatorial Pacific that enhances the ocean-atmosphere coupling. Our result provides predictive insight of El Nio after multiyear La Nia, and advances our understanding of ENSO transition under greenhouse warming.

DOI: 10.1016/j.scib.2024.12.034

Source: https://www.sciencedirect.com/science/article/pii/S2095927324009411