After each of the 1963 Agung, 1982 El Chichón, and 1991 Pinatubo eruptions, an El Niño was observed. The increased likelihood of an El Niño after a tropical eruption has also been found in long-term reconstructed proxy data. Through examining simulations over the last millennium by 11 different models, we show that a tropical volcano eruption can robustly excite a western-to-central equatorial Pacific (WCEP) westerly anomaly at 850 hPa in eight out of the 11 models; such a westerly anomaly is favorable for El Niño development. Under the volcanic forcing, there are significant extratropical continent surface cooling and tropical drying with negative precipitation anomalies over the South–South East Asia (SSEA), West African monsoon, and Intertropical Convergence Zone (ITCZ) regions. This common precipitation suppression response occurs in most of the models. Sensitivity experiments show that a WCEP westerly anomaly can be excited by the tropical land cooling, especially the SSEA cooling induced precipitation suppression rather than by the extratropical land surface cooling. Theoretical results show that a WCEP westerly anomaly is excited due to a Gill response to reduced precipitation over the SSEA and West African monsoon regions; and the SSEA contributes more than the West African monsoon does. The ITCZ weakening, however, excites an easterly wind anomaly. The models with more sensitive convective feedback tend to simulate an El Niño more easily, while a failed simulation of an El Niño after a robust westerly anomaly in some models calls for further studies on these models’ delayed responses to radiative forcing induced by volcano eruptions.

在1963年阿贡火山，1982年厄尔尼诺奇雄火山和1991年皮纳图博火山爆发后，都观测到了厄尔尼诺现象。在长期重建的代理数据中还发现了热带喷发后发生厄尔尼诺现象的可能性增加。通过检查11个不同模型在过去千年中的模拟，我们显示，热带火山喷发可以在11个模型中的8个中在850 hPa强烈激发西-中赤道太平洋西风异常。这种西风异常有利于厄尔尼诺现象的发展。在火山的强迫作用下，南亚东南亚（SSEA），西非季风和热带辐合带（ITCZ）地区存在明显的温带大陆表面冷却和热带干燥，且降水异常为负。在大多数模型中都会出现这种常见的降水抑制响应。敏感性实验表明，WCEP西风异常可由热带陆地降温，特别是由SSEA降温引起的降水抑制而不是由温带陆地降温来激发。理论结果表明，WCEP西风异常是由于吉尔对SSEA和西非季风地区降水减少的反应而引起的；SSEA的贡献超过了西非季风。但是，ITCZ减弱会激发东风异常。对流反馈更为敏感的模型往往更容易模拟厄尔尼诺现象，