Dissecting the polar dichotomy of the noncondensable gas enhancement on Mars using the NASA Ames Mars General Circulation Model

Steven M. Nelli, James R. Murphy, Ann L. Sprague, William V. Boynton, Kris E. Kerry, Daniel M. Janes, Albert E. Metzger

Research output: Contribution to journalArticle

12 Citations (Scopus)

Abstract

The atmospheric processes underlying the observed spatial and temporal enhancement of noncondensing gases in Mars' atmosphere are investigated. The Gamma Ray Spectrometer (GRS) on board Mars Odyssey has obtained measurements indicating that the absolute and relative column abundance of noncondensing gases (primarily argon and nitrogen) maximizes at high latitudes in both hemispheres during winter as CO2 gas condenses and forms the seasonal polar ice cap. This condensing CO2 "leaves behind" noncondensing gases whose local absolute and relative column abundances can increase at a rate controlled by mixing with less-enhanced air from lower latitudes. Understanding the processes responsible for the magnitude and seasonal variations of these enhancement values is an aid in understanding atmospheric transport processes. The NASA Ames Mars General Circulation Model is employed to help understand the atmospheric thermodynamical mechanisms that give rise to the observed temporal and magnitude variations in the polar enhancement values. The model produces a threefold noncondensable gas enhancement in the south polar region and an approximate 1.4-fold increase in noncondensables in the north polar region. These model results are temporally consistent with observed values, but the observed enhancement magnitudes exceed those modeled by up to a factor of two. The difference in strength and the season of formation between transient eddies in the southern and northern hemispheres may play a large role in determining the different character of the two polar enhancements. Model simulations also illuminate the effect that topography, orbital eccentricity, and atmospheric st opacity have on producing the north versus south polar enhancement dichotomy.

Original languageEnglish (US)
Article numberE08S91
JournalJournal of Geophysical Research: Space Physics
Volume112
Issue number8
DOIs
StatePublished - Aug 20 2007

Fingerprint

noncondensable gases
dichotomies
mars
NASA
general circulation model
Mars
Gases
augmentation
gas
polar region
polar regions
Gamma ray spectrometers
gases
Argon
atmospheric transport
ice cap
Opacity
Ice
Mars atmosphere
argon

ASJC Scopus subject areas

  • Oceanography
  • Astronomy and Astrophysics
  • Atmospheric Science
  • Space and Planetary Science
  • Earth and Planetary Sciences (miscellaneous)
  • Geophysics
  • Geochemistry and Petrology

Cite this

Dissecting the polar dichotomy of the noncondensable gas enhancement on Mars using the NASA Ames Mars General Circulation Model. / Nelli, Steven M.; Murphy, James R.; Sprague, Ann L.; Boynton, William V.; Kerry, Kris E.; Janes, Daniel M.; Metzger, Albert E.

In: Journal of Geophysical Research: Space Physics, Vol. 112, No. 8, E08S91, 20.08.2007.

Research output: Contribution to journalArticle

Nelli, Steven M. ; Murphy, James R. ; Sprague, Ann L. ; Boynton, William V. ; Kerry, Kris E. ; Janes, Daniel M. ; Metzger, Albert E. / Dissecting the polar dichotomy of the noncondensable gas enhancement on Mars using the NASA Ames Mars General Circulation Model. In: Journal of Geophysical Research: Space Physics. 2007 ; Vol. 112, No. 8.
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