Numerical simulation of the visible and near infrared radiance of Mars: effects of atmospheric scattering Original Research Article

This paper presents new simulations of the radiance of the surface and atmosphere of Mars. Our modeling is directly connected with future spectrometric measurements of two instruments on Mars Express (short-wavelength channel of PFS and OMEGA) and of the VIRTIS spectrometer on-board Rosetta which was planned for observation of Mars in August 2005. These instruments all cover a similar spectral range (∼0.2–6.0 μm) with various spectral resolutions (R ∼ 100–2000). The present simulations are intended to optimize instrument set-up, and to facilitate the interpretation of the data measured from Martian orbit. In simulations of the radiance in various viewing geometries, cumulative effects of the surface and atmosphere of Mars have been taken into account. Our calculations include the reflectance and emission of the surface as well as the solar radiation scattered and thermally emitted from the gases and dust in the Martian atmosphere. Soils are represented by two spectral types, a dark and a bright one, that encompass the whole range of reflectance and emittance observed. Atmospheric dust (basalt over dark regions and hematite over bright regions) has been taken into account using a continuous size distribution, and spectral optical parameters calculated from Mie scattering. A layer model is used for the atmosphere, together with temperature and pressure profiles derived from measurements by IRIS on Mariner9 and TES on MGS.