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Material ejection by the cold jets and temperature evolution of the south seasonal polar cap of Mars from THEMIS/CRISM observations and implications for surface properties

Pilorget, C. and Edwards, C. S. and Ehlmann, B. L. and Forget, F. and Millour, E. (2013) Material ejection by the cold jets and temperature evolution of the south seasonal polar cap of Mars from THEMIS/CRISM observations and implications for surface properties. Journal of Geophysical Research. Planets, 118 (12). pp. 2520-2536. ISSN 2169-9097. https://resolver.caltech.edu/CaltechAUTHORS:20140221-153943305

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Abstract

As the seasonal CO_2 ice polar caps of Mars retreat during spring, dark spots appear on the ice in some specific regions. These features are thought to result from basal sublimation of the transparent CO_2 ice followed by ejection of regolith-type material, which then covers the ice. We have used Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) reflectance data, Thermal Emission Imaging System (THEMIS) visible images, and THEMIS-derived temperature retrievals along with a thermal numerical model to constrain the physical and compositional characteristics of the seasonal cap for several areas exhibiting dark spots at both high spatial and temporal resolutions. Data analysis suggests an active period of material ejection (before solar longitude (Ls) 200), accumulation around the ejection points, and spreading of part of the ejected material over the whole area, followed by a period where no significant amount of material is ejected, followed by complete defrosting (≈ Ls 245). Dark material thickness on top of the CO_2 ice is estimated to range from a few hundreds of microns to a few millimeters in the warmest spots, based on numerical modeling combined with the observed temperature evolution. The nature of the venting process and the amount of material that is moved lead to the conclusion that it could have an important impact on the surface physical properties.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1002/2013JE004513DOIArticle
http://onlinelibrary.wiley.com/doi/10.1002/2013JE004513/abstractPublisherArticle
ORCID:
AuthorORCID
Ehlmann, B. L.0000-0002-2745-3240
Additional Information:© 2013 American Geophysical Union. Received 30 August 2013; revised 8 November 2013; accepted 11 November 2013; published 23 December 2013. We would like to thank the THEMIS and CRISM teams for providing the data and helping in the processing. We are also grateful to the JMARS team for making available their software. We thank P. Christensen, M. Vincendon, and S. Douté for fruitful discussions about these exotic polar processes. Finally, we are grateful to the two anonymous reviewers who provided constructive reviews that helped improving the manuscript.
Subject Keywords:Mars; ice; climate; surface temperature
Issue or Number:12
Record Number:CaltechAUTHORS:20140221-153943305
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20140221-153943305
Official Citation:Pilorget, C., C. S. Edwards, B. L. Ehlmann, F. Forget, and E. Millour (2013), Material ejection by the cold jets and temperature evolution of the south seasonal polar cap of Mars from THEMIS/CRISM observations and implications for surface properties, J. Geophys. Res. Planets, 118, 2520–2536, doi:10.1002/2013JE004513.
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:43935
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:25 Feb 2014 00:06
Last Modified:09 Mar 2020 13:18

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