Zonal Asymmetry in Ozone Variations Over Antarctic Stations During the Life Cycle of Sudden Stratospheric Warmings

The zonal asymmetry in the Antarctic total ozone column (TOC) has been widely studied in recent decades. However, little is known about how spatially dependent the TOC response is to sudden stratospheric warmings (SSWs). This paper analyzes the connection of zonally asymmetric variations of TOC with SSWs in September 1988, 2002, and 2019. The analysis is based on time series for 16 Antarctic research stations, gridded fields (MSR-2 TOC data), and the amplitude of zonal waves 1 and 2 in geopotential height (MERRA-2 reanalysis). We use a superposed epoch analysis for ±60-day time lags relative to the SSW central date to capture the main stages of the SSW life cycle. According to the TOC asymmetry pattern, a division between the Eastern Hemisphere (EH) and Western Hemisphere (WH) stations is used. The main results are zonally asymmetric variations in TOC anomalies near the SSW onset with the stronger (weaker) maximum in EH (WH), statistically significant at the 95% (89%) confidence level; precursor properties of the persistently growing positive anomalies in EH, and difference in timing of response maxima at day 0 in EH and day 7 in WH. These are previously unknown regional manifestations of Antarctic TOC anomalies. The results reveal statistically significant indicators of the possible SSW onset with a 1–2 weeks lead time. The dominant role of wave 1 and the zonally asymmetric Brewer–Dobson circulation in the observed EH–WH asymmetry is discussed.