The origin of ozone-rich air in the middle stratosphere observed over Europe at the end of January 1979

Daily ozone soundings over Switzerland in the winter of 1979 showed, at the end of January some extremely high values of the ozone mixing ration around the 10 mb level-9 to 10 ppm compared with a climatological mean of 6 ppm. At the same time, the temperature and ozone mixing ratio was measured by the LIMS experiment (Limb Infrared Monitor of the Stratosphere) on Nimbus 7. The single LIMS ozone profiles, as well as the LIMS 10 mb ozone maps, also showed extreme ozone maxima. Ozone transport was investigated by trajectory computations based on the LIMS geopotential height fields. Displacements and deformations of air parcel chains in 48 h were used to construct ozone maps, using the distribution on a previous day. The correspondence of such kinematically-constructed ozone maps using the actual LIMS maps is striking. This method is, thus, a strong indication of the self-consistency of the different LIMS products (ozone, temperature, geopotential) and explains the unusual ozone observations.