Conférence Master Arctic Studies à Guyancourt le 10 novembre à 14h: Jean-Pierre Pommereau (LATMOS): " The European Arctic Ozone campaigns and the monitoring of yearly ozone depletion by the SAOZ network". The discovery of the Antarctic ozone hole in 1985, and the threat of a similar event in the Arctic, prompted the start of ozone research in Europe. After first French-German balloon flights in 1987-89 in Kiruna in Northern Sweden within a CHEOPS project, an ambitious programme was set under the auspice of the General Direction Research of the European Commission. Under the direction of an “Ozone Panel” and an “Ozone Coordinating Unit”, several successive campaigns were set, involving balloon, aircraft and ground-based observations and associated modelling by a number of European and international scientists: EASOE in 1991-92, followed by SESAME in 1994-95, THESEO in 1998-99 and finally SOLVE-THESEO in 2000, a US-European collaborative effort. Altogether, they resulted in significant progress in ozone science and a large number of publications, but equally important, in the building of a strong European atmospheric scientific community and the development of powerful experimental and modelling tools of great use for the ongoing Chemistry-Climate research programmes. However, the story is not finished. If the European Ozone campaigns resulted in the full understanding of the mechanism responsible, the ozone depletion is still continuing in the Arctic and the Antarctic and predictions show that it should continue for several decades. There is still no sign of “recovery”. Described here will be the effort of LATMOS for the yearly evaluation of the amount of depletion during the winter from the SAOZ stations deployed in the Arctic combined with stratospheric chemistry modelling.