Response of Arctic ozone to sudden stratospheric warmings

• Published in: Atmospheric chemistry and physics 2018-11, Vol.18 (22), p.16499-16513
• Main Authors: de la Cámara, Alvaro, Abalos, Marta, Hitchcock, Peter, Calvo, Natalia, Garcia, Rolando R
• Format: Article
• Language: English
• Subjects: Advective transport; Annual variations; Anomalies; Arctic ozone; Atmospheric chemistry; Atmospheric circulation; Atmospheric composition; Climate; Climate models; Climatology; Duration; Dynamics; Environmental aspects; Evolution; Fluxes; Global warming; Interannual variability; Life cycle; Life cycle analysis; Life cycle engineering; Life cycles; Mixing ratio; Natural history; Organic chemistry; Ozone; Ozone concentration; Ozone mixing ratio; Polar environments; Quantitative analysis; Recovery; Satellite data; Satellites; Sciences of the Universe; Seasonal variability; Stratosphere; Stratospheric circulation; Stratospheric warming; Transport; Upper stratosphere; Vortices; Wave drag
• ISSN: 1680-7324; 1680-7316; 1680-7324
• DOI: 10.5194/acp-18-16499-2018

Sudden stratospheric warmings (SSWs) are the main source of intra-seasonal and interannual variability in the extratropical stratosphere. The profound alterations to the stratospheric circulation that accompany such events produce rapid changes in the atmospheric composition. The goal of this study is to deepen our understanding of the dynamics that control changes of Arctic ozone during the life cycle of SSWs, providing a quantitative analysis of advective transport and mixing. We use output from four ensemble members (60 years each) of the Whole Atmospheric Community Climate Model version 4 performed for the Chemistry Climate Model Initiative and also use reanalysis and satellite data for validation purposes. The composite evolution of ozone displays positive mixing ratio anomalies of up to 0.5–0.6 ppmv above 550 K (∼ 50 hPa) around the central warming date and negative anomalies below (−0.2 to −0.3 ppmv), consistently in observations, reanalysis, and the model. Our analysis shows a clear temporal offset between ozone eddy transport and diffusive ozone fluxes. The initial changes in ozone are mainly driven by isentropic eddy fluxes linked to enhanced wave drag responsible for the SSW. The recovery of climatological values in the aftermath of SSWs is slower in the lower than in the upper stratosphere and is driven by the competing effects of cross-isentropic motions (which work towards the recovery) and isentropic irreversible mixing (which delays the recovery). These features are enhanced in strength and duration during sufficiently deep SSWs, particularly those followed by polar-night jet oscillation (PJO) events. It is found that SSW-induced ozone concentration anomalies below 600 K (∼ 40 hPa), as well as total column estimates, persist around 1 month longer in PJO than in non-PJO warmings.