The ENSO and QBO Impact on Ozone Variability and Stratosphere‐Troposphere Exchange Relative to the Subtropical Jets

Abstract

The El Niño–Southern Oscillation (ENSO) and the Quasi‐Biennial Oscillation (QBO) are natural sources of ozone variability in the tropical and midlatitude upper troposphere and lower stratosphere. Regional tropospheric ozone variations have previously been attributed to ENSO‐ and QBO‐induced changes in stratosphere‐troposphere exchange around the subtropical jets (STJs). We use Goddard Earth Observing System Data Assimilation System analyses of Ozone Monitoring Instrument and Microwave Limb Sounder ozone data mapped to a STJ coordinate to examine the influence of ENSO and QBO on global and regional variability of upper troposphere and lower stratosphere ozone, and tropopause folding stratosphere‐troposphere exchange. These coordinates eliminate the apparent variability due to the changing location of the STJ, which is itself influenced by ENSO. The ENSO influence on ozone variability near the STJ and in tropopause folds is much greater than the QBO influence, although both are small in a hemispheric mean. On regional scales, the ozone sensitivity to ENSO associated with tropopause folding is strongly positive in some regions and strongly negative in others, which largely cancel in the hemispheric mean. Poleward of the STJs, the sensitivities of stratospheric ozone to ENSO and QBO are large and similar in magnitude but are opposite in phase. Thus, the ozone responses to ENSO and QBO can largely cancel or reinforce, depending on their relative phases. These results can be used to evaluate and compare modeled QBO and ENSO influences on ozone variability that removes the first‐order impact of differences in the location of the STJs.

Analysis of recent lower-stratospheric ozone trends in chemistry climate models

“…No major volcanic eruption occurred during the analysed period, so we disregard this source of variability. The influence of the QBO and ENSO on the hemispheric mean mid-latitude ozone is of the same magnitude, and thus they can both impact LS ozone trends, as shown by the study of Olsen et al (2019). We know from earlier studies that the QBO has a strong dynamical effect on the sub-tropical and mid-latitude LS ozone (e.g.…”

From the middle stratosphere to the surface, using nitrous oxide to constrain the stratosphere–troposphere exchange of ozone

“…In a previous work (Ruiz et al, 2021; hereafter R2021), we showed that historical simulations with three chemistry transport models (CTMs) were able to match the interannual surface variations observed in N 2 O. These were clearly driven by the stratospheric quasi-biennial oscillation (QBO), which appears to be the major interannual signal in stratospheric circulation and STE (Kinnersley and Tung, 1999;Baldwin et al, 2001;Olsen et al, 2019). In this work, we calculate the monthly latitudinal STE fluxes of O 3 , N 2 O, and CFCl 3 (F11), establish a coherent picture relating fluxes to observed abundances, and summarize the methods in Sect.…”

Subseasonal prediction of springtime Pacific–North American transport using upper-level wind forecasts

“…However, retrospectively isolating such associations, which is equivalent to conducting a "perfect model" forecast, does not assure that current operational forecast models can successfully predict those relationships, particularly on subseasonal timescales (e.g., Lavers et al, 2016;Baggett et al, 2017). Nevertheless, some teleconnection and transport patterns appear to be potentially predictable on subseasonal timescales (e.g., Mundhenk et al, 2018;Wang and Robertson, 2019;Pan et al, 2019;DeFlorio et al, 2019;Yamagami and Matsueda, 2020), though these forecasts are typically found to occur during boreal winter.…”

“…1 are in part a reflection of the different physical processes that govern them, as outlined above. However, at least a portion of STT and TME seasonality and variability are linked by one important commonality: they are both directly modulated by large-scale Rossby waves (e.g., Ryoo et al, 2013;Albers et al, 2018), which themselves owe their propagation and breaking patterns to the strength and location of the subtropical and polar front jets (Hoskins and Ambrizzi, 1993;Scott and Cammas, 2002;Abatzoglou and Magnusdottir, 2006;Hitchman and Huesmann, 2007;Mundhenk et al, 2016;Olsen et al, 2019). For example, high TME is often observed on the western edge of blocking anticyclones in the North Pacific, where air is rising (Mundhenk et al, 2016), while STT occurs east of the block, where sinking air and PV intrusions frequently develop .…”