37th DPS Meeting, 4-9 September 2005
Session 24 Mars III
Oral, Tuesday, September 6, 2005, 2:00-3:50pm, Music Concert Hall

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[24.08] GRS Measurements of Ar in Mars' Atmosphere

A.L. Sprague, W.V. Boynton, K.E. Kerry, D.M. Janes, N.J. Kelly, M.K. Crombie, D.M. Hunten (LPL), S.M. Nelli, J.R. Murphy (NMSU), R.C. Reedy (UNM), A.E. Metzger (JPL)

One and one half Mars years of atmospheric argon (Ar) measurements are described in the context of understanding how Ar, a minor constituent of Mars atmosphere that does not condense at Mars temperatures, can be used to study martian circulation and dynamics. There is a repeated factor of 6 enhancement of Ar measured over south polar latitudes. The maximum in Ar abundance occurs near the onset of southern winter. There is no similar strong enhancement of Ar over north-polar regions during northern winter; only modest evidence for an enhancement peak is present. Part of this difference is explained by the global topographic dichotomy and the fact that the duration of northern autumn and winter is shorter than southern autumn and winter. Rapid seasonal fluctuations in Ar abundance may indicate evidence for wave activity at the perimeter of the southern seasonal polar cap. The apparent lack of coincidence of Ar enhancement with the relatively cold, cryptic terrain or relatively warm, bright albedo regions, indirectly supports the conclusion that the low temperatures measured over the south polar region by IRTM are probably caused by the combination of low CO2 abundance over south polar night and low emissivity regions on the surface associated with small grain size.

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Bulletin of the American Astronomical Society, 37 #3
© 2004. The American Astronomical Soceity.