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AGU: Geophysical Research Letters

 

Keywords

  • Mars
  • temperature
  • exosphere

Index Terms

  • Atmospheric Composition and Structure: Pollution: urban and regional
  • Atmospheric Composition and Structure: Pressure, density, and temperature
  • Atmospheric Composition and Structure: Exosphere
  • Atmospheric Composition and Structure: Thermosphere: energy deposition
  • Atmospheric Processes: Thermospheric dynamics

Abstract

GEOPHYSICAL RESEARCH LETTERS, VOL. 35, L01201, 4 PP., 2008
doi:10.1029/2007GL031904

Solar flux variability of Mars' exosphere densities and temperatures

Jeffrey M. Forbes

Department of Aerospace Engineering Sciences, University of Colorado, Boulder, Colorado, USA

Frank G. Lemoine

NASA Goddard Space Flight Center, Greenbelt, Maryland, USA

Sean L. Bruinsma

Department of Terrestrial and Planetary Geodesy, Centre Nationale D'Etudes Spatiales, Toulouse, France

Michael D. Smith

NASA Goddard Space Flight Center, Greenbelt, Maryland, USA

Xiaoli Zhang

Department of Aerospace Engineering Sciences, University of Colorado, Boulder, Colorado, USA

Using densities derived from precise orbit determination of the Mars Global Surveyor (MGS) spacecraft from 1999 to mid-2005, the response of Mars' exosphere to long-term solar change is established and compared to that of Earth and Venus. At Mars, exosphere temperatures (weighted towards high-latitude Southern Hemisphere daytime conditions) change only 36–50% as much as those at Earth as solar activity increases from solar minimum to solar maximum, whereas the response at Venus is one-fifth that at Mars. General circulation models suggest that this difference may be strongly influenced by adiabatic cooling associated with the thermosphere general circulation. However, other processes such as differences in CO2 cooling rates may also be playing a role.

Received 5 September 2007; accepted 20 November 2007; published 10 January 2008.

Citation: Forbes, J. M., F. G. Lemoine, S. L. Bruinsma, M. D. Smith, and X. Zhang (2008), Solar flux variability of Mars' exosphere densities and temperatures, Geophys. Res. Lett., 35, L01201, doi:10.1029/2007GL031904.

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