Interannual and seasonal behavior of Martian residual ice-cap albedo

Shane Byrne, M. T. Zuber, G. A. Neumann

Research output: Contribution to journalArticle

24 Citations (Scopus)

Abstract

The Mars Orbiter Laser Altimeter (MOLA), functioning as a high-resolution radiometer, has observed several appearances of the Martian residual ice caps. We examine these data to quantify both seasonal behavior and interannual differences. The northern residual cap (NRC) was found to be mostly stable with the exception of one, previously identified, region of strong variability. Interannual change in the extent of the NRC appears to be small and reversible on timescales of 1 or 2 years. The NRC has an elaborate seasonal evolution of albedo. Annuli of fine-grained CO2 and water frost, which track the inner and outer edges of the seasonal CO2 cap, cause large temporary brightenings. The NRC albedo is stable from just after solstice to Ls 150°, after which albedo decreases steadily. This late-summer darkening can be explained by shadowing within the rough topography of the NRC, leading to a lower limit on topographic relief of 80 cm. The southern residual cap (SRC) appears stable in extent. As has been previously discovered, its seasonal frost albedo behavior appears to be correlated with insolation. However, residual CO2 appears not to share this characteristic; we use this behavioral difference to infer net deposition of CO2 ice on the SRC during 1 out of 3 years. Uncharacteristically, the SRC abruptly darkens at Ls 320° in 1 Martian year (year beginning April 2002). Circumstantial evidence suggests atmospheric scattering by dust is responsible. The 2001 global dust-storm appears, either, to have had no effect on the polar cap albedos, or, resulted in slightly brighter ice deposits.

Original languageEnglish (US)
Pages (from-to)194-211
Number of pages18
JournalPlanetary and Space Science
Volume56
Issue number2
DOIs
StatePublished - Feb 2008

Fingerprint

ice cap
albedo
caps
ice
frost
dust storm
insolation
altimeter
radiometer
Mars
relief
laser
scattering
atmospheric scattering
topography
dust
timescale
dust storms
Mars Global Surveyor
darkening

Keywords

  • Albedo
  • Ice
  • Interannual
  • Mars
  • Polar
  • Radiometry

ASJC Scopus subject areas

  • Geophysics
  • Space and Planetary Science
  • Astronomy and Astrophysics

Cite this

Interannual and seasonal behavior of Martian residual ice-cap albedo. / Byrne, Shane; Zuber, M. T.; Neumann, G. A.

In: Planetary and Space Science, Vol. 56, No. 2, 02.2008, p. 194-211.

Research output: Contribution to journalArticle

Byrne, Shane ; Zuber, M. T. ; Neumann, G. A. / Interannual and seasonal behavior of Martian residual ice-cap albedo. In: Planetary and Space Science. 2008 ; Vol. 56, No. 2. pp. 194-211.
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