CLONO2 VERTICAL PROFILE AND ESTIMATED MIXING RATIOS OF CLO AND HOCL IN WINTER ARCTIC STRATOSPHERE FROM MICHELSON INTERFEROMETER FOR PASSIVEATMOSPHERIC SOUNDING LIMB EMISSION-SPECTRA

Nighttime limb emission spectra recorded by the balloon-borne Michelso n interferometer for passive atmospheric sounding (MIPAS) on February 11, 1995, near Kiruna were used to infer a vertical profile of ClONO2 as well as estimates of ClO and HOCl volume mixing ratios, The highest ClONO2 mixing ratio (2.6 parts per billion by volume (ppbv)) was foun d at 22.69 km altitude and is explained by an early recovery of this c hlorine reservoir in the upper part of the formerly chlorine-activated height range, Inferred nighttime ClO mixing ratios appear to be rathe r high for the lower stratosphere (0.38 ppbv at 16.43 km altitude) and indicate chlorine activation at this altitude region, The HOCl mixing ratio is estimated as 0.03 ppbv at 28.04 km altitude, while for lower altitudes the HOCl concentrations are clearly below the detection lim it of MIPAS. The measurements are compared with three-dimensional chem ical transport model calculations, Results agree reasonably well but s how differences in detail.