Application of radiative transfer and retrieval procedures to study the Martian atmosphere

Abstract

A Planetary Fourier Spectrometer (PFS) onboard a future Mars mission will record a big amount of data on spatial and temporal variation of atmospheric radiance spectra. The calculation of synthetic spectra in the absorption bands of molecules and aerosols and the comparison with measurements is a fundamental background for many studies of planetary atmospheres. A radiative transfer simulation technique is described that will be applied to retrieve atmospheric parameters from the measured infrared signatures. A prestored set of absorption cross-sections which is based on quasi-monochromatic line-by-line calculations is used to predict the transmission functions for CO2, CO and H2O at 2.0 cm_-1 resolution in a layered atmosphere. Synthetic spectra of the Martian emergent radiance have been calculated in the 200-8000 cm_-1 wavenumber range (1.25-25 muem) for a variety of atmospheric models including the surface contribution. The influence of multiple scattering by different types of aerosols on radiative transfer is investigated on the basis of a successive order technique. Retrieval procedures and theoretical results for temperature profiles will be discussed.