HR: 1340h
AN: P23B-1353    [Abstracts]
TI: Titan's sand seas of longitudinal dunes as indicators of winds and sediment transport
AU: * Radebaugh, J
EM: jani.radebaugh@byu.edu
AF: Department of Geological Sciences, Brigham Young University, Provo, UT 84602, United States
AU: Lorenz, R D
AF: Johns Hopkins University, APL, Laurel, MD 20723,
AU: Lunine, J I
AF: Lunar and Planetary Lab, Univ of Arizona, Tucson, AZ 85721,
AU: Wall, S D
AF: Jet Propulsion Lab, 4800 Oak Grove Dr, Pasadena, CA 91109,
AU: Spencer, C
AF: Department of Geological Sciences, Brigham Young University, Provo, UT 84602, United States
AU: Kirk, R L
AF: US Geol Survey, Astrogeology Div, Flagstaff, AZ 86001,
AU: Lopes, R M
AF: Jet Propulsion Lab, 4800 Oak Grove Dr, Pasadena, CA 91109,
AU: Stofan, E R
AF: Proxemy Research, Inc, Bowie, MD 20715,
AU: Allison, M
AF: Goddard Inst, Space Studies, New York, NY 10025,
AU: Callahan, P
AF: Jet Propulsion Lab, 4800 Oak Grove Dr, Pasadena, CA 91109,
AU: Cassini Radar Team, T
AB: The Cassini Titan Radar Mapper has revealed nearly ten thousand longitudinal dunes on the surface of Titan, mainly within +-30 deg latitude [1,2,3]. Based on dune orientations, divergence around topography, similarity to dune fields on Earth, and other features such as bright streaks, the prevailing wind hypothesis model for longitudinal dune formation is favored, in which winds blow generally parallel to the dune long axis [e.g.5,6,7]. On Titan, these winds are dominantly Eastward [2,3], but as observed in more recent Radar swaths (2,4,5/2007) there is Northeastward deviation from this direction at higher latitudes. Vast fields of longitudinal dunes at Titan's equatorial regions are described as sand seas [2,3]. On Earth, these regions are typified not so much by the transport as by the accumulation of sand. This may occur when there is a large nearby source of sand or when there is reduced sand removal due to decreased winds or topographic obstacles [7,8,9]. Sand transport could be inhibited both upwind and downwind of the topographically complex region Xanadu, for example. Seasonally reversing wind regimes could also lead to the stagnation of sand transportation and net accumulation within sand sea regions [7,8,9]. This scenario may help reconcile global wind model predictions with directionality opposed to that predicted from observation. Sand seas on Earth are formed in arid regions and in some places cover 30-40 percent of the surface [8], a percent coverage similar to that in the equatorial regions on Titan [2,3]. Sand seas on Earth are long-lived, having taken up to tens of thousands of years to accumulate; whether the Titan dunes are more or less stable is an outstanding question. [1] Elachi et al. 2006. [2] Lorenz et al. 2006. [3] Radebaugh et al. in rev. [4] Stofan et al. 2007. [5] Fryberger and Dean 1979. [6] Tsoar 1983. [7] Lancaster 1982. [8] Lancaster 1995. [9] Fryberger and Ahlbrandt 1979.
DE: 3319 General circulation (1223)
DE: 3322 Land/atmosphere interactions (1218, 1631, 1843)
DE: 5464 Remote sensing
SC: Planetary Sciences [P]
MN: 2007 Fall Meeting