1Service d’Aeronomie, CNRS, Verrières le Buisson, France
2Belgian Institute for Space Aeronomy (BIRA), Brussels, Belgium
3Danish Meteorological Institute, Copenhagen, Denmark
4Institute for Air Research, Kjeller, Norway
5Central Aerological Observatory, Moscow, Russia
6Finnish Meteorological Institute, Sodankylä, Finland
7School of the Environment, University of Leeds, Leeds, UK
Abstract. Total column ozone reduction in the Arctic is evaluated each winter since 1993/1994 by the transport method (3-D CTM passive ozone minus measurements). The cumulative loss from 1 December to the end of the season ranges from 5–10% during warm winters like 1998/1999, 2000/2001 and 2001/2002 up to 30%–32% during cold winters like 1994/1995 and 1995/1996. The 23% cumulative loss observed during the winter 2002/2003 is similar in amplitude to the 20–24% measured in 1996/1997 and 1999/2000 but the timing is different. It started unusually early in December after the occurrence of very low temperature at all stratospheric levels between 550 K and 435 K allowing PSC formation and thus chlorine activation. The early ozone loss of 2002/2003 is well captured by current 3-D CTM models.