Aharonson, Oded and Zuber, Maria T. and Smith, David E. and Neumann, Gregory A. and Feldman, William C. and Prettyman, Thomas H. (2004) Depth, distribution, and density of CO2 deposition on Mars. Journal of Geophysical Research E, 109 (E05). E05004. ISSN 0148-0227 http://resolver.caltech.edu/CaltechAUTHORS:AHAjgre04
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Observations by the Mars Orbiter Laser Altimeter have been used to detect subtle changes of the polar surface height during the course of seasonal cycles that correlate with the expected pattern of CO2 deposition and sublimation. Using altimetric crossover residuals from the Mars Orbiter Laser Altimeter, we show that while zonally averaged data capture the global behavior of CO2 exchange, there is a dependence of the pattern on longitude. At the highest latitudes the surface height change is as high as 1.5–2 m peak to peak, and it decreases equatorward. Decomposition of the signal into harmonics in time allows inspection of the spatial pattern and shows that the annual component is strongly correlated with the residual south polar cap deposits and, to a lesser extent, with the north polar cap. In the north, the second harmonic (semiannual) component correlates with the location of the ice deposits. The phases of the annual cycles are in agreement with observations by the Thermal Emission Spectrometer of the timing of the annual disappearance of CO2 frost from the surface at the high latitudes. At lower latitudes, frost sublimation (“Crocus date”) predates the mean depositional minima, as expected. These global-scale, volumetric measurements of the distribution of condensed CO2 can be combined with measurements of the deposited column mass density derived from the Neutron Spectrometer on board Mars Odyssey to yield an estimate of the density of the seasonally exchanging material of 0.5 ± 0.1 g/cm^3. These constraints should be considered in models of the Martian climate system and volatile cycles.
|Additional Information:||Copyright 2004 by the American Geophysical Union. Received 6 December 2003; revised 5 February 2004; accepted 29 March 2004; published 20 May 2004. We acknowledge helpful discussions with Hugh Kieffer and suggestions by two anonymous reviewers. This work was supported by the NASA Mars Data Analysis Program and Mars Exploration Program.|
|Subject Keywords:||CO2, deposition, Mars|
|Official Citation:||Aharonson, O., M. T. Zuber, D. E. Smith, G. A. Neumann, W. C. Feldman, and T. H. Prettyman (2004), Depth, distribution, and density of CO2 deposition on Mars, J. Geophys. Res., 109, E05004, doi:10.1029/2003JE002223.|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Archive Administrator|
|Deposited On:||16 Jan 2009 03:37|
|Last Modified:||26 Dec 2012 10:43|
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