ILAS observations of chemical ozone loss in the Arctic vortex during earlyspring 1997

Chemical ozone loss rates were estimated for the Arctic stratospheric vorte x by using ozone profile data (Version 3.10) obtained with the Improved Lim b Atmospheric Spectrometer (ILAS) for the spring of 1997. The analysis meth od is similar to the Match technique, in which an air parcel that the ILAS sounded twice at different locations and at different times was searched fr om the ILAS data set, and an ozone change rate was calculated from the two profiles. A statistical analysis indicates that the maximum ozone loss rate was found on the 450 K potential temperature surface in February, amountin g to 84 ppbv/day. The integrated ozone loss for two months from February to March 1997 showed its maximum of 1.5+/-0.1 ppmv at the surface that follow ed the diabatic descent of the air parcels and reached the 425 K level on M arch 31. This is about 50% of the initial (February 1) ozone concentration. The present study demonstrated that data from a solar occultation sensor w ith a moderate altitude resolution can be used for the Match analysis.