Development of ozone depletion over the years

Chemical ozone depletion is not a quantity that can be measured directly. Ozone is also influenced by atmospheric transport. The time at which the polar vortex breaks down varies from year to year. One way to deduce the effect of chemical ozone depletion from the measurements is tto look at of the average ozone column in the polar vortex ("equivalent latitude" >63°). This quantity increases after the breakdown of the polar vortex (typically in March) due to the the transport of ozone-rich air masses towards the pole. Therefore the minimum of this quantity in March is an approximate measure of chemical ozone depletion in the Arctic. Here you can see this value for years up to and including 2021 and also the corresponding time series for Antarctica.

Minimum of the mean ozone column in the polar vortex (top) for March in the Arctic (below) for October in the Antarctic derived from the ozone climatology of Bodeker Scientific and OMI satellite data. Open symbols for years in which at the time the polar vortex was already broken down. After Müller et al. (2008) [1]