Measuring HCFC22 from the MIPAS instrument

Abstract. Hydrochlorofluorocarbon-22 (HCFC-22) is an important trace constituent in the atmosphere through its role as a greenhouse gas and its potential influence on stratospheric ozone chemistry. Current estimates of its vertical distribution are limited to infrequent and sparse balloon and aircraft campaigns, giving poor spatial coverage. In particular, knowledge of variations in its global vertical profile is poor but can be improved by utilising satellite remote sensing techniques. By using a limb sounding, spectrally resolving, instrument such as the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) onboard ENVISAT, with a resolution of 0.025 cm-1 unapodized, it is possible to distinguish the emission features of up to 30 trace species from the more densely packed spectral lines of the major constituent species such as CO2 and H2O. Atmospheric concentrations of these trace gases can be obtained by inversion of the measured spectra. The work presented here focuses on a study using optimal estimation techniques to retrieve vertical profile concentrations of HCFC-22 from MIPAS spectral data. 1.