j@1040: 
j@1040: Development of ozone depletion over the years
j@1040: =============================================
j@1040: 
j@1040: Chemical ozone depletion is not a quantity that can be measured
j@1040: directly.  Ozone is also influenced by atmospheric transport. The time
j@1040: at which the polar vortex breaks down varies from year to year.  One
j@1040: way to deduce the effect of chemical ozone depletion from the
j@1040: measurements is tto look at of the average ozone column in the polar
j@1040: vortex ("equivalent latitude" >63°). This quantity increases
j@1040: after the breakdown of the polar vortex (typically in March) due to
j@1040: the the transport of ozone-rich air masses towards the pole.
j@1040: Therefore the minimum of this quantity in March is an approximate measure
j@1040: of chemical ozone depletion in the Arctic. Here you can see this
j@1303: value for years up to and including 2021 and also the corresponding
j@1040: time series for Antarctica.