Arctic Tropospheric Ozone Chemistry
The European Commission, DG XII, has published the final report of the ARCTOC project (1994-1996). This project, supported by the EC's Environment and Climate research programme, aimed to gain an understanding of sudden polar tropospheric ozone loss events which were discovered about ten years ago. It consisted of coordinated field, laboratory and modelling activities. Eight research groups were involved from five European countries and also from Canada, the United States and New Zealand. The report discusses the results of these activities, and gives an indication of the remaining questions concerning this phenomenon which have still to be answered. The main result of the project has been to increase knowledge of tropospheric ozone drops in the Arctic region. The report states that the polar boundary layer ozone depletion observed is caused by bromine and chlorine compounds during favourable meteorological conditions, and indicates that anthropogenic influence plays only a minor role in this phenomenon.