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[51.10] Effects of Variable Atmospheric Dust on the Surface and Atmospheric Absorption in the Polar Cap Regions on Mars

P. B. James, B. Bonev (Univ. of Toledo), M. J. Wolff (Space Science Institute)

We report our first results on the effects of dust on the CO₂ sublimation in the Martian polar cups. The Spherical Discrete Ordinate Method for 3D atmospheric radiative transfer (Evans, K. F. 1998, Journ. Atm. Sci, 55, 429) has been used in order to examine the dust effect on the surface and atmospheric absorption as a function of the dust extinction, surface albedo, and solar zenith angle. A constant mixing ratio is assumed for the vertical distribution of the dust, with the scattering phase function adopted from Clancy & Lee (1991, Icarus, 93, 135). The albedo of single scattering of the dust for 600 nm is adopted from Wolff et al. (1997, JGR, 102, 1679). The effect of the atmospheric dust is fairly complex, depending on the solar zenith angle, dust opacity, and surface albedo. The presented results will be ultimately used to study the interannual variability in the polar cap recession that can be produced by variable dust. This research was supported by a Mars Data Analysis Grant NAG5-8183.