Oxford MIPAS Arctic O3

The plot above shows the average ozone column above the 100 mb pressure (approx 15km altitude) in the Arctic Vortex, while the plot below shows the average for the region polewards of the 65degN latitude circle, as determined from the Oxford retrievals of data from the MIPAS instrument on the ESA Envisat satellite.

The Vortex region is (crudely) estimated by taking the profiles with the mininum temperature at 30 mb corresponding to an area equivalent to that polewards of 80deg N (about 16% of the total area averaged in the lower plot).

Comparing the two plots, note in particular the decline in vortex ozone that often occurs in Jan/Feb

Unlike the Antarctic, there is no obvious equivalent of the "ozone hole" (which would be expected to develop during February and March if it just followed the Antarctic behaviour shifted by half a year). This is due to higher minimum temperatures and a less well-confined polar vortex in the Arctic.

The steep rise ozone towards the end of January 2009 was due to a particularly strong 'stratospheric sudden warming' when the polar vortex became displaced and ozone-rich air from lower latitudes is drawn in.