INTERCOMPARISON OF ATMOSPHERIC RADIATION SCHEMES FOR THE LOWER MARTIAN ATMOSPHERE.

Interpretation of the vast data flow from the recent and ongoing Mars missions requires extensive modeling activ-ity to support the investigations and conclusions drawn from the observations. We have initiated a campaign to compare atmospheric radiation schemes for the lower Martian atmo-sphere with least-compromise reference line-by-line calcula-tions (Meadows and Crisp 1996, Crisp 1986). By using fixed reference conditions we are introducing an intercomparison framework to enable atmospheric modeling teams to compare their modeling results with the reference line-by-line calcula-tions, and to improve their models. The atmosphere of Mars is thin and therefore its response to local radiative forcing is strong when compared to that of the Earth’s troposphere. Airborne dust and also the water va-por give significant contributions to the radiative fluxes. Thus models of the Martian atmosphere should have fairly accu-rate radiative transfer (RT) algorithms. This is specifically important for the net radiative flux at the surface, which is the main driver for the surface temperature evolution, since the surface turbulent fluxes are small due to the thin atmosphere (e.g. Haberle et al. 1993, Savijärvi 1991a, Savijärvi 1991b, Savijärvi 1999). However, the accuracy of the RT schemes has not been rigorously tested in many cases as reference calcula-tions have been rare. We introduce a set of reference cases for Martian atmo-spheric conditions with profiles for temperature, pressure, dus