Remote Sensing of Atmospheric Trace Constituents Using Fourier Transform Spectrometry

The investigation of changes in ozone concentration and of the increase of the greenhouse effect requires simultaneous and global observations of atmospheric trace species. Obviously, IR‐Fourier Transform Spectrometers (FTIR) are especially appropriate for this measurement task due to their capability to detect wide spectral intervals with high spectral resolution. FTIR experiments for measuring trace species have already been performed during the last ten years. Some of the very interesting results as derived from these measurements are presented, for example the wide range of mixing ratio profiles and the variety of trace gases detected by the ATMOS (Atmospheric Trace Molecule Spectroscopy) experiment. These contributions to atmospheric research were already essential even if no cooled interferometer for time‐independent emission measurements has been flown aboard aircrafts or in space so far. – The objective to fly a cooled FTIR in space leads to a novel optical design, the socalled double pendulum interferometer (DPI). The DPI is the core part of several MIPAS (Michelson Interferometer for Passive Atmospheric Sounding) experiments which have already been used for atmospheric measurements. Infrared solar absorption spectra of the atmosphere were taken during the CHEOPS III campaign in Sweden in winter 1990 in order to obtain time series of zenith column amounts of several trace gases. The first two field experiments of the cooled MIPAS have been performed during stratospheric balloon flights in France in May 1989 and 1990. Limb emission spectra were measured within the altitude range between 7 and 38 km. A number of atmospheric trace species are identified, namely CO2, O3, H2O, CH4, N2O, CCl4, CF2Cl2, CFCl3, CHF2Cl, ClONO2, HNO3, N2O5 and C2H6. Besides the MIPAS ground based and the MIPAS balloon experiment our new cooled MIPAS aircraft experiment will be operated during the EASOE (European Arctic Stratospheric Ozone Exp.) campaign as scheduled for winter 1991/92. The cooled MIPAS space experiment is in development for the 1. European Polar Platform and the German Environmental Research Satellite ATMOS.