Abstract. While the impact of El Niño-Southern Oscillation (ENSO) on the stratospheric circulation has been long recognized, its effects on stratospheric ozone have been less investigated. In particular, the impact on ozone of different ENSO flavors, Eastern Pacific (EP) El Niño and Central Pacific (CP) El Niño, as well as the driving mechanisms for the ozone variations have not been investigated to date. This study aims to explore these open questions by examining the anomalies in advective transport, mixing and chemistry associated with different El Niño flavors (EP and CP) and La Niña in the Northern Hemisphere in boreal winter. For this purpose, we use four 60-year ensemble members of the Whole Atmospheric Community Climate Model version 4. The results show a significant ENSO signal on total column ozone (TCO) during EP El Niño and La Niña events. During EP El Niño events, TCO is significantly reduced in the tropics and enhanced at middle and high latitudes in boreal winter. The opposite response has been found during La Niña. Interestingly, CP El Niño has no significant impact on extratropical TCO while its signal in the tropics is weaker than for EP El Niño events. The analysis of mechanisms reveals that advection through changes in tropical upwelling is the main driver for ozone variations in the lower tropical stratosphere, with a contribution of chemical processes above 30 hPa. At middle and high latitudes, stratospheric ozone variations related to ENSO result from combined changes in advection by residual circulation downwelling and changes in horizontal mixing linked to Rossby wave breaking and polar vortex anomalies. The impact of CP El Niño on the shallow branch of the residual circulation is small, and no significant impact is found on the deep branch.

中文翻译：

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ENSO对平流层臭氧影响的驱动机制

摘要。虽然厄尔尼诺-南方涛动 (ENSO) 对平流层环流的影响早已得到认可，但其对平流层臭氧的影响却很少被研究。特别是，迄今为止尚未研究不同ENSO风味，东太平洋（EP）厄尔尼诺和中太平洋（CP）厄尔尼诺对臭氧的影响，以及臭氧变化的驱动机制。本研究旨在通过检查与北方冬季北半球不同厄尔尼诺现象（EP 和 CP）和拉尼娜现象相关的平流传输、混合和化学异常来探索这些未解决的问题。为此，我们使用了整个大气社区气候模型版本 4 的四个 60 年集合成员。结果显示，在 EP 厄尔尼诺和拉尼娜事件期间，总臭氧柱 (TCO) 上有显着的 ENSO 信号。在 EP 厄尔尼诺事件期间，热带地区的 TCO 显着降低，北方冬季中高纬度地区的 TCO 增加。在拉尼娜期间发现了相反的反应。有趣的是，CP 厄尔尼诺对温带 TCO 没有显着影响，而其在热带的信号比 EP 厄尔尼诺事件弱。机制分析表明，通过热带上升流变化的平流是低热带平流层臭氧变化的主要驱动力，其中化学过程的贡献高于 30 hPa。在中高纬度地区，与 ENSO 相关的平流层臭氧变化是由残余环流下涌引起的平流变化和与罗斯贝波破坏和极涡异常相关的水平混合变化共同引起的。