37th DPS Meeting, 4-9 September 2005
Session 33 Mars' Atmosphere
Poster, Tuesday, September 6, 2005, 6:00-7:15pm, Music Recital Room

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[33.12] Using the NASA Ames General Circulation Model to evaluate the importance of dust devils on the evolution of surface dust reservoirs on Mars

M.A. Kahre, J.R. Murphy (New Mexico State University), R.M. Haberle (NASA Ames Research Center)

Aeolian processes dominate the current surface environment on Mars. The observed dust cycle includes surface dust raising by small-scale (dust devil) and larger scale (wind stress) lifting processes. Additionally, the current cycle depends on the availability of surface dust to be lifted. Surface dust deposits provide the dust for the current cycle but the depth evolution of these regions depends on the spatial pattern of preferential dust lifting and deposition. Source regions that currently experience net deflation could have been net deposition regions during past climate regimes. Surface dust deposits are known to currently reside in the Arabia, Tharsis, and Elysium regions, and are believed to be on the order of a meter deep.

We will present numerical results that address the temporal evolution of surface dust availability in these low thermal inertia regions under current climatic conditions. The presented simulations were conducted with a version of the NASA Ames Mars General Circulation Model (GCM) that includes lifting, transport, and deposition of radiatively active dust. Two dust lifting mechanisms are accounted for: wind stress lifting and dust devil lifting. A wide range of dust lifting parameters (stress threshold for lifting, surface dust flux vs. stress magnitude, etc.) are investigated to explore the dust cycle and surface dust deposition/deflation sensitivities. Simulation results indicate that all three of the low thermal-inertia continents (Arabia, Tharsis, and Elysium) currently experience small magnitude (<1 \mum of dust per year) net surface dust deflation. This net deflation is the result of dust devil dust lifting, indicating that dust devils play an important role in the present day pattern of surface dust reservoirs.

This work was partially funded by the NASA Graduate Student Researchers Program.

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