Assessment of total ozone trends and their driving factors at three Antarctic stations in 2007–2023

The aim of this study is to assess trends in the total ozone column (TOC) and the atmospheric factors influencing ozone variability at three Antarctic stations (Marambio, Troll and Concordia) in the period 2007–2023. For this purpose, ground-based TOC measurements were used supplemented by satellite observations from the Ozone Monitoring Instrument on board the NASA's Aura satellite. TOC trends were derived using a multiple linear regression model provided by the Long-term Ozone Trends and Uncertainties in the Stratosphere (LOTUS) project. The selected LOTUS model was able to explain 95–98 % of the TOC variability at all three stations. Several predictors were evaluated in the regression model, and it was found that the lower stratospheric temperature and the polar stratospheric cloud volume contribute most to the ozone variability at these stations. A statistically significant increasing trend was found at the Marambio station (3.33 DU/decade), while the statistically insignificant trends were detected at the other two stations. Using MERRA-2 reanalyses, the LOTUS model was applied to each grid point in the 40–90°S region, which effectively illustrates the spatial distribution of the impacts of individual predictors. It was found that warmer conditions in the Antarctic stratosphere in September 2019 caused TOC to be up to 100 DU higher than normal, especially over East Antarctica. The results contribute to a better understanding of regional TOC trends and the influence of atmospheric factors on TOC in the southern high latitudes, which is essential for assessing how the Antarctic ozone layer responds to changes in ozone-depleting substances under the Montreal Protocol regulations.