36th DPS Meeting, 8-12 November 2004
Session 37 Mars Atmosphere
Poster II, Thursday, November 11, 2004, 4:15-7:00pm, Exhibition Hall 1A

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[37.04] Distribution of Argon in Mars' Atmosphere As Measured by the GRS on Mars Odyssey: Aid to Understanding Martian Meteorology

A. L. Sprague, W.V. Boynton, K.E. Kerry, D.M. Janes (LPL, U of AZ), R.C. Reedy (U of NM), A.E. Metzger (JPL)

Measurements made by the 2001 Mars Odyssey Gamma Ray Spectrometer (GRS) of the flux of 1294 keV gamma rays resulting from the decay of 41Ar show significant variations with season and latitude. The atmosphere is enriched with Ar relative to CO2 over both the southern and northern polar regions during Winter with the greater enhancement observed in the south. While the Ar concentration increases until Winter solstice over the northern polar region, fluctuations in the relative amount of Ar in Autumn and Winter indicate periodic mixing of atmosphere from lower latitudes. In contrast, the rise in Ar concentration over the south polar region reaches a well-defined maximum at the beginning of Winter and then smoothly drops to a minimum in Spring. These differences in Ar behavior indicate differences in mixing characteristics between the northern and southern polar regions. Both polar regions exhibit a significant drop in Ar concentration in late Winter and Spring as the polar atmosphere is mixed with pure CO2 from the subliming perimeter of the CO2 ice caps. We acknowledge the contributions of the entire GRS team and support from NASA.

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Bulletin of the American Astronomical Society, 36 #4
© 2004. The American Astronomical Soceity.