Analysis of Antarctic ozone trends from 1979 to 2023

Antarctic column ozone has shown signs of a sustained recovery since 2000, but levels were distinctly low during 2020–2022, potentially affecting estimates of ozone recovery and long-term trends. To assess the impact of recent low ozone on long-term variability, we analyse total column ozone (TCO) data from the World Ozone and Ultraviolet Radiation Centre, multi-sensor reanalysis, and Total Ozone Mapping Spectrometer/Ozone Monitoring Instrument. Ozone fields from the TOMCAT 3-D chemical transport model are also used to gain better insight into the changes. Multiple linear regression (MLR) is applied to estimate ozone trends over Antarctica from 1979 to 2023, incorporating proxies representing key chemical and dynamical processes such as the El Niño-Southern Oscillation and the Brewer–Dobson circulation (BDC).

Our analysis confirms that TCO declined across all datasets before 2000. The annual mean decreased at a rate of 2 Dobson units per year (DU yr‾¹), while more pronounced decreases of approximately 6 DU yr‾¹ occurred in September and October. For the 2001–2019 period, TCO showed signs of recovery in the annual mean (0.5 DU yr‾¹) and September (1.5 DU yr‾¹), while the annual trend shifted to −0.4 DU yr‾¹ and September trend was near zero over the extended 2001–2023 period. The MLR effectively captures long-term ozone changes as well as unusual dynamical events such as the sudden stratospheric warmings in 2002 and 2019. Annual mean and springtime (September/October) TCO exhibited a positive correlation with the estimated BDC contribution throughout the 2001–2023 period. As dynamical proxies show the largest influence, we use TOMCAT simulations to illustrate the impact of the BDC on the Antarctic ozone. Two sensitivity simulations further demonstrate that the strengthening (weakening) of the circulation leads to high (low) ozone values in spring. Cold temperatures and abnormal BDC in 2021–2022 resulted in low ozone levels. These findings suggest that now ozone-depleting substances have been effectively controlled, dynamical processes are playing an increasingly important role in controlling the ozone recovery patterns in Antarctica.