DPS 2001 meeting, November 2001
Session 27. Mars Atmosphere I: Circulation
Oral, Chairs: J. Hollingsworth, A. Toigo, Thursday, November 29, 2001, 10:30am-12:30pm, Regency E

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[27.12] Noncondensables As Predictors of Martian Climate and Chemistry

C. England (Engineering Research Group), M.L. Delitsky (Jet Propulsion Laboratory)

The substantial seasonal changes in atmospheric pressure on Mars result from massive sublimation of carbon dioxide at the Poles. When CO2 is condensing, the mixing ratios of the low-boiling components (O2, CO, Ne, N2, Ar, Kr, and O3) in the atmosphere can increase locally up to 20-fold [1]. These non-condensing gases will disperse from the Pole prior to reintroduction of the CO2 into the atmosphere in the warmer seasons. As a result, there will exist a ``wave" of changing composition for minor components in the atmosphere that precedes the seasonal global pressure wave. The compositional wave can be a predictor of changes in martian climate, which is caused by the gross seasonal variation in atmospheric mass.

The greatest seasonal change is attributable to sublimation at the South Pole, which, in the fall and winter, removes up to 30% of the atmosphere. Selective condensation of CO2 may result locally in an atmosphere with up to 2.8% oxygen and over 50% nitrogen [1]. The average global mixing ratios of the non-condensables will change measurably. Increasing mixing ratios will anticipate the coming global rise in pressure and atmospheric mass. Because the compositional wave will not be uniform over the planet's surface, the changes in mixing ratio throughout the year can be indicators of the detailed movement of the atmosphere as it oscillates between poles.

Inert gases such as neon and krypton act as invariant tracers for atmospheric transport, while oxygen, carbon monoxide and ozone are subject to transport and chemistry. Of particular theoretical interest is the apparent deficit of carbon monoxide, produced from CO2 in amounts twice that of oxygen, but is present at only half the latter's concentration. Continuous and quantitative measurement of trace components over the full year may provide the key information for understanding the atmosphere, how it is affected by seasonal effects, and how it interacts with the regolith. Engineering methods to utilize the compositional changes for resource recovery are being studied [1].

[1] England, C, and Hrubes, J.D., ``MARRS: The Mars Atmosphere Resource Recovery System," NASA Institute for Advanced Concepts, July 24, 2001.

The author(s) of this abstract have provided an email address for comments about the abstract: cengland@earthlink.net

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