Ozone depletion in the Arctic winter 2007-2008

The Arctic winter 2007-08 was characterized by cold temperatures and a strong vortex. Potentials for large areas of ice and Polar Stratospheric Clouds (PSCs) are observed during the winter. A vortex wide denitrification (removal of 60-80% of NOy) and intense chlorine activation (0.6 to 1.05 ppb of ClO) are found inside the vortex at 475 K. This chemical morphology triggered a high rate of ozone loss during the winter. The simulated results from MIMOSA-CHIM show a large loss of ozone at 425-550 K from January to March, about 1.5-2.3 ppm. The vortex averaged loss at 475 K is about 2.5 ppm in mid-March, which is in very good agreement with the estimated loss (2.3 ppm) from the Microwave Limb Sounder (MLS) measurements. Similar analyses from MIMOSA-CHIM for recent winters show a cumulative loss of 2.1 ppm in 2006-07 and 2.0 ppm in 2004-05 in tune with the measurements. The measured and simulated results show the highest loss in 2007-08 in comparison with the analyses for the last four winters at 475 K.