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Spectra from the modern field proof FTIR radiometer system OASIS in the near and the thermal infrared at a resolution of 1 cm(-1) are applied to the derivation of various atmospheric properties. To ensure reliable quantitative calibration, two high precision calibration black body cavities at different temperatures are frequently viewed between target measurements. The non-linear calibration of the MCT-detector in the thermal infrared has been derived with the help of a cold black body cavity at temperatures down to -70degreesC.

A retrieval procedure for temperature and humidity profiles, based on standard matrix inversion techniques of the linearized radiative transfer equation, has been implemented and successful application examples have been collected in several instances. Examples of a time development of profiles over 3 cloud free days during the LACE'98 campaign and of the dissolution of a strong nighttime inversion during the morning hours show the potential use of this technique.

The study of the infrared spectra in a case of a forest fire aerosol cloud reveals the potential to study aerosol emission signals in the infrared windows. Considerable emission in the displayed case allows to estimate a possible addition of a few W/m(2) to the downward longwave radiative fluxes at the surface by atmospheric aerosols.