AAS 200th meeting, Albuquerque, NM, June 2002
Session 12. Planets and Comets
Display, Monday, June 3, 2002, 9:20am-6:30pm, SW Exhibit Hall

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[12.02] Interrelationship Between the Dust and Water Cycles in the Martian Atmosphere: Numerical Modeling Studies

S.M. Nelli, J.R. Murphy (NMSU)

Mars’ low-mass, primarily carbon dioxide atmosphere contains quantities of both water vapor and suspended dust particles. Suspended dust can have a significant impact upon the atmospheric thermal state as the dust warms and cools via absorption and emission of radiant energy. Water vapor condensing onto the dust grains will change the radiative characteristics of both. Small dust particles can potentially be carried to great altitudes and affect the temperatures there. One potential limiting factor in the vertical extent of the dust is water vapor condensation. If water vapor present in the atmosphere condenses upon a dust particle, the particle’s gravitational sedimentation speed can be increased, and the likelihood of it being transported to high altitudes is diminished. Thus, water can act as a controlling mechanism with regard to the vertical extent of dust mixing. At the same time, the atmosphere’s water vapor holding capacity is very strongly temperature dependent: the greater the temperature, the greater the potential water vapor mixing ratio (if a source of water or ice is available). Thus, there is a potentially significant interplay between the Martian dust and water cycles.

Previous research done using computer modeling to better understand the Martian atmosphere treat the dust and the water cycles as two separate and independent processes. The existing numerical model will be improved to simulate the relationship between the Martian dust and water cycles by actually coupling the two cycles. The model will condense the water onto the dust allowing the particles radiative characteristics, fall speeds, and as a result, their vertical distribution to change. Data obtained from the Viking, Mars Pathfinder, and especially the Mars Global Surveyor missions will be used to determine the accuracy of the model results. Preliminary results will be presented at the June 2002 meeting.

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Bulletin of the American Astronomical Society, 34
© 2002. The American Astronomical Soceity.