Simulation of Aerosol and Water Vapor Transport with the GFDL Mars General Circulation Model.

R.J. Wilson (GFDL/NOAA), M.I. Richardson (UCLA), R.T. Clancy (SSI, Boulder), A.V. Rodin (IKI, Moscow)

Observations of the martian atmosphere reveal a strong annual modulation of atmospheric temperature that is evidently due to the pronounced seasonal asymmetry in solar radiation and the highly variable distribution of aerosol. The implied variations in thermal forcing are closely coupled to the character and vigor of the atmospheric general circulation through the raising and transport dust. The GFDL Mars GCM has been developed to investigate the interaction between thermal forcing and the atmospheric circulation, most notably the Hadley circulation and the thermal tides (Wilson and Hamilton, 1996). Using a prescribed aerosol source in the bottom atmospheric layer, the model self-consistently calculates aerosol transport and radiative heating. For example, with a sufficiently rapid injection of aerosol into the atmosphere, a realistic simulation of the 1977b global dust storm and associated winter polar warming may be obtained (Wilson, 1997). Sources and sinks of water vapor and condensate and their transport have also been incorporated in the GCM in order to explore arguments (Clancy et al. 1996) that the water vapor distribution may play a role in establishing and maintaining a relatively clear and cold atmosphere during the Northern hemisphere summer season. Simulations indicate that inclusion of possible radiative and sedimentation effects of water-ice-coated dust can have a significant interactive effect on the aerosol and temperature distribution in the martian tropical region. We will present results for a variety of dust source scenarios which illustrate the role of aerosol in the martian climate.