Summary
To measure chemical induced ozone loss in the Arctic lower stratosphere the Match method was developed. Trajectory calculations based on stratospheric wind fields of the European Center of Medium-range Weather Forecasts (ECMWF) are used to track and to predict the ways of air parcels. The forecast part of the trajectories allows an active coordination of the soundings at joining ozonesonde stations in order to probe air parcels by two ozonesondes at different locations and times along the trajectory. A statistical analysis of the measured differences in ozone mixing ratio and the time the air parcel spent in sunlight between the measurements provides the chemical ozone loss. This technique to determine the development of ozone loss has been transferred to the Antarctic lower stratosphere. Nine ozonesonde stations performed approx. 400 successful ozonesonde launches from June to October 2003. Ozone loss rates of up to 7 ppbv per sunlit hour (or 75 ppbv per day) were found inside the polar vortex on the 475 K potential temperature surface (about 19 km in altitude) in the first half of September 2003. This strong ozone loss coincides with the heavy increase of sunlight into the vortex core after the Antarctic winter. During the whole period of time temperatures were low enough for polar stratospheric clouds, including ice clouds, to form. This experimental data is used to evaluate and to improve our current understanding of the ozone loss chemistry. A comparison of model results, done by a box model, and the experimental data is also shown. This work is part of the EC supported project "Quantitative Understanding of Ozone losses by Bipolar investigations" (QUOBI).