DETERMINATION OF THE STRATOSPHERIC ORGANIC CHLORINE BUDGET IN THE SPRING ARCTIC VORTEX FROM MIPAS-B LIMB EMISSION-SPECTRA AND AIR SAMPLING EXPERIMENTS

Vertical profiles of halogenated source gases, CF2Cl2, CFCl3, CHF2Cl, Cl-4, and CF4, were retrieved from limb emission spectra recorded by t he Michelson Interferometer for Passive Atmospheric Sounding, Balloonb orne version (MIPAS B) during a balloon flight launched from Esrange n ear Kiruna, northern Sweden (68 degrees N) on March 14, 1992. This fli ght was a contribution to the balloon launch program of the European A rctic Stratospheric Ozone Experiment (EASOE) campaign. All problems en countered during the analysis of the recorded spectra are discussed in detail. These are primarily the lack of spectral data for HNO3 which interferes with the CF2Cl2 nu(6) band, and the strong effects attribut ed to the Pinatubo aerosol. As the air mass sounded by MIPAS was polar vortex air, these data supplement the results of in situ air sampling experiments, which investigated air masses outside or at the edge of the polar vortex at altitudes below is km during the last phase of EAS OE. An analysis is made of the vertical profiles of the seven most abu ndant organic chlorine species (CF2Cl2, CFCl3, CHF2Cl, CCl4, CH3Cl, CH 3CCl3, and C2F3C3) during that phase of the EASOE campaign. Mixing rat ios of those organic chlorine compounds which had not been measured by MIPAS are inferred from profiles provided by air sampling experiments performed between November 30, 1991, and March 12, 1992. These profil es were adjusted to the dynamic conditions during the MIPAS observatio ns, namely the effect of subsidence, using CF2Cl2 as a tracer. This al lowed to derive the relative contributions of the organic chlorine spe cies to the total chlorine budget of the air mass sounded by MIPAS. Th e results are consistent with the high ClONO2 mixing ratio of 2.6 part s per billion by volume (ppbv) observed at 18.9-km altitude during thi s flight of MIPAS B.