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South Pole Station Ozonesondes: Variability in the 2019-2021 Springtime Antarctic Ozone Holes

B. Johnson1, P. Cullis2,1 and J. Booth1

1NOAA Global Monitoring Laboratory (GML), Boulder, CO 80305; 303-497-6842, E-mail: Bryan.Johnson@noaa.gov
2Cooperative Institute for Research in Environmental Sciences (CIRES), University of Colorado, Boulder, CO 80309

Balloon-borne ozonesondes launched weekly from South Pole station (1986-2021) measure high vertical resolution profiles of ozone and temperature from surface to 30-35 km altitude. The launch frequency is increased in late winter before the onset of rapid stratospheric ozone loss in September. Ozone hole metrics show the yearly 14-21 km column ozone minimums and September loss rates remain on an upward (less severe) trend since 2001. However, the data series also illustrate interannual variability, especially in the last three years (2019-2021). Here we show additional details of these three years comparing minimum profiles and July to December 14-21 km column time series. The 2019 anomalous vortex breakdown showed stratospheric temperatures began warming followed by reduced ozone loss in early September. The minimum total column ozone of 180 Dobson Units (DU) was observed on 24 Sep. This was followed by two stable and cold polar vortex years in 2020 and 2021 with total column ozone minimums at 104 DU (01 Oct) and 102 DU (07 Oct), respectively. These years also showed broad zero ozone (saturation loss) within the 14-21 km layer by the end of September which persisted into October.  

Figure 1

Figure 1. Selected ozonesonde profiles from 2019-2021 representing the ozone hole severity over South Pole by comparing the average winter profile before depletion begins (blue) to the minimum profile (red).  The gray-shaded region represents the 1986-2018 median 30-70th percentile during the two periods.