THE MINIHOLE EVENT ON 6 FEB 1990 - INFLUENCE OF MIE-SCATTERING ON THEEVALUATION OF SPECTROSCOPIC MEASUREMENTS

Groundbased differential optical absorption spectroscopic measurements of stratospheric trace gases are sensitive to stratospheric aerosol ( PSC) layers as measured at Feb. 6, 1990, over northern Scandinavia. Mi e extinction alters the intensity distribution of zenith scattered sun light, in an extreme case presented here this can lead to 30 % - 40 % changes of the airmass factor (AMF) for ozone. NO2 and OClO AMFs chang e less, O2 AMFs change dramatically. Ozone measurements at Kiruna, Swe den, for the time Feb. 4 - 8, 1990 are reported. No significant change in the O3 total column was observed during that period, when the effe ct of PSC's on the AMF was taken into account.