HR: 14:25h
AN: NG43A-04    [Abstracts]
TI: Modeling Aeolian Sediment Transport Thresholds on Mars: A Shear Stress Partitioning Approach
AU: * Gillies, J A
EM: jackg@dri.edu
AF: Division of Atmospheric Sciences, Desert Research Institute, 2215 Raggio Parkway, Reno, NV 89512, United States
AU: King, J
EM: james.king@dri.edu
AF: Division of Atmospheric Sciences, Desert Research Institute, 2215 Raggio Parkway, Reno, NV 89512, United States
AU: Lancaster, N
EM: nick@dri.edu
AF: Division of Earth and Ecosystem Sciences, Desert Research Institute, 2215 Raggio Parkway, Reno, NV 89512, United States
AU: Nickling, W G
EM: nickling@uoguelph.ca
AF: Wind Erosion Laboratory,Department of geography, University of Guelph, University of Guelph, Guelph, ON N1G 2W1, Canada
AB: This presentation explores the effect that larger roughness elements may have on entrainment of sediment by Martian winds using a shear stress partitioning approach based on a model developed by Raupach et al. (1993). This model predicts the shear stress partitioning ratio, i.e., the percent reduction in shear stress on the intervening surface between the roughness elements as compared to the surface in the absence of those elements, as a function of the geometric properties of the roughness elements, the characteristic drag coefficients of the elements and the surface, and the assumed effect these elements have on the spatial distribution of the mean and maximum shear stresses. Recent work by King et al. (2005) and field testing by Gillies et al. (2006, 2007) have demonstrated that this model can effectively predict roughness effects on entrainment threshold for terrestrial atmospheric conditions. As the model can be used for different fluid properties it makes it applicable to evaluating how the atmospheric conditions and winds of Mars interact with the roughness to predict the effect that roughness will have on sediment entrainment there. Utilizing the results of Gillies et al. (2007), which provides data on the effect large solid roughness elements of varying roughness density have on shear stress partitioning and particle threshold and aerodynamic parameters, this paper will use the shear stress partitioning model to evaluate how Martian atmospheric conditions will affect threshold on Martian surfaces with the same range of roughness evaluated by Gillies et al. (2006, 2007). Finally, based on available estimates of roughness density for Mars drawn from the literature, estimates of threshold wind speeds for these rough surfaces will be presented.
DE: 1622 Earth system modeling (1225)
DE: 1631 Land/atmosphere interactions (1218, 1843, 3322)
DE: 1824 Geomorphology: general (1625)
DE: 4430 Complex systems
DE: 4490 Turbulence (3379, 4568, 7863)
SC: Nonlinear Geophysics [NG]
MN: 2007 Fall Meeting