HR: 0800h
AN: P11A-0260    [Abstracts]
TI: Non-condensable gas in a Mars General Circulation Model
AU: * Guo, X
EM: xin@gps.caltech.edu
AF: Division of Geological and Planetary Science, California Institute of Technology, MC 150- 21, 1200 E. California Blvd., Pasadena, CA 91125, United States
AU: Richardson, M I
EM: mir@gps.caltech.edu
AF: Division of Geological and Planetary Science, California Institute of Technology, MC 150- 21, 1200 E. California Blvd., Pasadena, CA 91125, United States
AU: Newman, C
EM: claire@gps.caltech.edu
AF: Division of Geological and Planetary Science, California Institute of Technology, MC 150- 21, 1200 E. California Blvd., Pasadena, CA 91125, United States
AU: Sprague, A L
EM: sprague@lpl.arizona.edu
AF: Lunar and Planetary Laboratory, Lunar and Planetary Laboratory, Tucson, AZ 85721, United States
AU: Boynton, W V
EM: wboynton@lpl.arizona.edu
AF: Lunar and Planetary Laboratory, Lunar and Planetary Laboratory, Tucson, AZ 85721, United States
AB: We model the variation of non-condensable trace gases that results from the seasonal cycle of CO₂ on Mars. A simple condensation scheme has been incorporated into MarsWRF, a 3-dimensional numerical model for the atmospheres of Mars. Non-condensable trace gas (mostly N₂ and Ar) mass mixing ratios are affected by the phase change of CO₂ and by transport. The distribution of Ar abundance has been observed by the Gamma Ray Spectrometer on the Mars 2001 Odyssey spacecraft. We are able to qualitatively reproduce the Ar observations, including the seasonal evolving latitudinal distribution. However, the modeled magnitudes of maximum enrichment are lower than observed. Smoothing Ar enrichment in the vertical reduces susceptibility to transport by near-surface, off-cap circulation, therefore gives further enhancement of non-condensable tracer in the winter pole. We suggest that a missing process in the model may account for the underestimation. An extra buoyancy term in the dynamics should result from the vertical gradient in mean molecular mass as Ar mass mixing ratio increases.
DE: 0343 Planetary atmospheres (5210, 5405, 5704)
DE: 5405 Atmospheres (0343, 1060)
DE: 5422 Ices
DE: 5462 Polar regions
DE: 6225 Mars
SC: Planetary Sciences [P]
MN: 2007 Fall Meeting