Le Gall, A. and Hayes, A. G. and Ewing, R. and Janssen, M. A. and Radebaugh, J. and Savage, C. and Encrenaz, P. (2012) Latitudinal and altitudinal controls of Titan’s dune field morphometry. Icarus, 217 (1). pp. 231-242. ISSN 0019-1035 http://resolver.caltech.edu/CaltechAUTHORS:20120229-085746316
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Dune fields dominate ∼13% of Titan’s surface and represent an important sink of carbon in the methane cycle. Herein, we discuss correlations in dune morphometry with altitude and latitude. These correlations, which have important implications in terms of geological processes and climate on Titan, are investigated through the microwave electromagnetic signatures of dune fields using Cassini radar and radiometry observations. The backscatter and emissivity from Titan’s dune terrains are primarily controlled by the amount of interdune area within the radar footprint and are also expected to vary with the degree of the interdunal sand cover. Using SAR-derived topography, we find that Titan’s main dune fields (Shangri-La, Fensal, Belet and Aztlan) tend to occupy the lowest elevation areas in Equatorial regions occurring at mean elevations between ∼−400 and ∼0 m (relative to the geoid). In elevated dune terrains, we show a definite trend towards a smaller dune to interdune ratio and possibly a thinner sand cover in the interdune areas. A similar correlation is observed with latitude, suggesting that the quantity of windblown sand in the dune fields tends to decrease as one moves farther north. The altitudinal trend among Titan’s sand seas is consistent with the idea that sediment source zones most probably occur in lowlands, which would reduce the sand supply toward elevated regions. The latitudinal preference could result from a gradual increase in dampness with latitude due to the asymmetric seasonal forcing associated with Titan’s current orbital configuration unless it is indicative of a latitudinal preference in the sand source distribution or wind transport capacity.
|Additional Information:||© 2011 Elsevier Inc. Received 16 May 2011. Revised 11 October 2011. Accepted 31 October 2011. Available online 19 November 2011. This work was supported by the Cassini/Huygens mission, which is a joint endeavor of NASA, the European Space Agency (ESA), and the Italian Space Agency (ASI) and is managed by JPL/ Caltech under a contract with NASA. A. Le Gall is supported by the NASA Postdoctoral Program, administrated by Oak Ridge Associated Universities (ORAU). The authors are grateful to Don Jennings for sharing his CIRS measurements of the latitudinal ground temperature distribution. They also wish to thank Oded Aharonson for providing essential facilities for this work and Lori Fenton for her thoughtful comments that greatly help improving this manuscript.|
|Subject Keywords:||Titan Radar observations Radio observations Geological processes|
|Official Citation:||A. Le Gall, A.G. Hayes, R. Ewing, M.A. Janssen, J. Radebaugh, C. Savage, P. Encrenaz, the Cassini Radar Team, Latitudinal and altitudinal controls of Titan’s dune field morphometry, Icarus, Volume 217, Issue 1, January 2012, Pages 231-242, ISSN 0019-1035, 10.1016/j.icarus.2011.10.024. (http://www.sciencedirect.com/science/article/pii/S0019103511004179)|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Ruth Sustaita|
|Deposited On:||29 Feb 2012 21:01|
|Last Modified:||29 Feb 2012 21:01|
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