State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, China.
Laboratory for Regional Oceanography and Numerical Modeling, Qingdao National Laboratory for Marine Science and Technology, Qingdao, 266237, China.
Nat Commun. 2023 Jan 24;14(1):394. doi: 10.1038/s41467-023-36053-7.
El Niño has been recorded to change its properties since the 1980s, characterized by more common extreme El Niño and Central Pacific (CP) El Niño events. However, it is still unclear whether such change is externally forced or part of the natural variability. Here, we find that the frequency of the extreme and CP El Niño events also increased during the period 1875-1905, when the anthropogenic CO2 concentration was relatively lower, but with a positive phase of the Atlantic Multidecadal Oscillation (AMO). Models and palaeoclimate proxies reveal that a positive AMO enhances the zonal sea surface temperature gradient in the CP, which strengthens zonal advective feedback, favoring extreme and CP El Niño development. Moreover, we estimate that internal variability contributed to ~65% of the increasingly extreme and CP El Niño events, while anthropogenic forcing has made our globe experience ~1 more extreme and ~2 more CP events over the past four decades.
自 20 世纪 80 年代以来，人们已经记录到厄尔尼诺现象的性质发生了变化，其特征是更常见的极端厄尔尼诺和中太平洋（CP）厄尔尼诺事件。然而，这种变化是否是外部强迫的还是自然变率的一部分仍不清楚。在这里，我们发现，在人为 CO2 浓度相对较低但大西洋多年代际振荡（AMO）处于正相位的 1875-1905 年期间，极端和 CP 厄尔尼诺事件的频率也增加了。模型和古气候代用指标表明，正的 AMO 增强了 CP 中的纬向海表温度梯度，从而加强了纬向平流反馈，有利于极端和 CP 厄尔尼诺的发展。此外，我们估计内部变率对过去四十年中越来越多的极端和 CP 厄尔尼诺事件的贡献约为 65%，而人为强迫使我们的地球经历了约 1 次更极端和 2 次更多的 CP 事件。
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