Abstract The stratospheric quasi-biennial oscillation (QBO) is known to cause variations in the transport of chemical tracers but the role of chemical processes in modulating their QBO signals remains unclear. Using ozone observations (Stratospheric Water and OzOne Satellite Homogenized, SWOOSH) and a chemical transport model (SLIMCAT), we analyze the role of chemical processes in the QBO impact on stratospheric ozone in the tropics and Northern Hemisphere during winter and early spring over the period 1979–2015. During easterly QBO (EQBO) phases tropical ozone concentrations decrease in the lower stratosphere (40–100 hPa, ∼16–23 km) and in the middle stratosphere (above 15 hPa, ∼30 km) but increase in the transition region between 15 and 40 hPa (∼23–30 km) compared to the westerly (WQBO) phases. Although the contributions of chemical processes to ozone QBO signal are less than those of dynamical processes, this study highlights the non-negligible role of chemical processes in the ozone QBO signal. The negative chemical ozone tendencies in the tropical lower stratosphere, that are attributed to less downward ultraviolet radiation and weaker oxygen photolysis, partially contribute to the negative ozone anomalies at this altitude during EQBO phases, particularly in February and March. In contrast, the negative chemical ozone tendencies related to more NO2 and stronger NO2-catalyzed ozone loss cannot explain the ozone increases in the transition region during EQBO phases, which is mainly caused by the QBO-induced transport of ozone-rich air from above. The positive chemical ozone tendencies in the extratropics during EQBO phases are mainly related to lower temperatures and less active catalytic ozone loss cycles. In addition, reduction in polar stratospheric cloud occurrence associated with the warmer Arctic stratosphere during EQBO phases weakens the heterogeneous chemical processes in the lower stratosphere and decreases chlorine activation, partially contributing to the positive chemical ozone tendency and ozone increases in this region.

中文翻译：

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化学过程在平流层臭氧准双年振荡 (QBO) 信号中的作用

摘要 众所周知，平流层准双年振荡 (QBO) 会导致化学示踪剂传输的变化，但化学过程在调节其 QBO 信号中的作用仍不清楚。使用臭氧观测（平流层水和 OzOne 卫星均质化，SWOOSH）和化学传输模型 (SLIMCAT)，我们分析了化学过程在 QBO 在冬季和早春期间对热带和北半球平流层臭氧的影响中的作用1979-2015 年。在东风 QBO (EQBO) 阶段，热带臭氧浓度在平流层下部（40-100 hPa，~16-23 km）和平流层中部（15 hPa 以上，~30 km）降低，但在 15 到 15 hPa 之间的过渡区域增加与西风 (WQBO) 相相比，40 hPa (∼23–30 km)。尽管化学过程对臭氧 QBO 信号的贡献小于动态过程的贡献，但本研究强调了化学过程在臭氧 QBO 信号中不可忽视的作用。热带低平流层的负化学臭氧趋势，归因于较少的向下紫外线辐射和较弱的氧光解作用，在 EQBO 阶段，特别是在 2 月和 3 月期间，部分导致该高度的负臭氧异常。相比之下，与更多的 NO2 和更强的 NO2 催化的臭氧损失相关的负化学臭氧趋势无法解释 EQBO 阶段过渡区域的臭氧增加，这主要是由 QBO 诱导的从上方输送富含臭氧的空气引起​​的。在 EQBO 阶段，温带地区的正化学臭氧趋势主要与较低的温度和较不活跃的催化臭氧损失循环有关。此外，在 EQBO 阶段，与较暖的北极平流层相关的极地平流层云发生的减少削弱了平流层下部的异质化学过程并减少了氯的活化，部分促成了该地区的化学臭氧正趋势和臭氧增加。