Jia Fan, Cai Wenju, Geng Tao, Gan Bolan, Zhong Wenxiu, Wu Lixin, McPhaden Michael J
Key Laboratory of Ocean Observation and Forecasting and Key Laboratory of Ocean Circulation and Waves, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266000, China; Laoshan Laboratory, Qingdao 266237, China.
Laoshan Laboratory, Qingdao 266237, China; Frontier Science Center for Deep Ocean Multispheres and Earth System (FDOMES) and Physical Oceanography Laboratory, Ocean University of China, Qingdao 266100, China; State Key Laboratory of Loess and Quaternary Geology, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an 710061, China; State Key Laboratory of Marine Environmental Science & College of Ocean and Earth Sciences, Xiamen University, Xiamen 361005, China.
Sci Bull (Beijing). 2025 Mar 15;70(5):756-764. doi: 10.1016/j.scib.2024.12.034. Epub 2024 Dec 25.
El Niño-Southern Oscillation (ENSO) exhibits a strong asymmetry between warm El Niño and cold La Niña in amplitude and temporal evolution. An El Niño often leads to a heat discharge in the equatorial Pacific conducive to its rapid termination and transition to a La Niña, whereas a La Niña persists and recharges the equatorial Pacific for consecutive years preconditioning development of a subsequent El Niño, as occurred in 2020-2023. Whether the multiyear-long heat recharge increases the likelihood of a transition to a strong El Niño 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 Niña, 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 Niño. 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 Niño after multiyear La Niña, and advances our understanding of ENSO transition under greenhouse warming.
厄尔尼诺-南方涛动（ENSO）在暖厄尔尼诺和冷拉尼娜之间的振幅和时间演变上表现出强烈的不对称性。一次厄尔尼诺现象通常会导致赤道太平洋的热量释放，这有利于其迅速结束并转变为拉尼娜现象，而一次拉尼娜现象会持续存在，并为赤道太平洋连续数年补充热量，为随后的厄尔尼诺现象的发展创造条件，就像2020 - 2023年发生的那样。持续多年的热量补充是否会增加向强厄尔尼诺转变的可能性仍然未知。在这里，我们表明这种转变很少见，但在温室气体短暂变暖的情况下更有可能发生。在多年拉尼娜现象后的北半球春季和初夏，尽管西太平洋有大量热量补充，但赤道中太平洋的温跃层仍然异常浅薄，海表面温度（SST）仍然异常寒冷。寒冷的状况抑制了随后大气深对流从温暖的西太平洋向东移动，延迟了海气耦合的开始，从而也延迟了厄尔尼诺现象的发展。在高排放情景下，这种转变仍然很少见，但可能性增加了两倍多。预计的变化与气候平均纬向海表面温度梯度的减弱相一致，这种减弱促进了大气对流的向东移动，同时也与赤道太平洋上层海洋层结的增强相一致，这种增强加强了海气耦合。我们的结果为多年拉尼娜现象后的厄尔尼诺现象提供了预测性见解，并增进了我们对温室气体变暖下ENSO转变的理解。
