GSA Annual Meeting in Denver, Colorado, USA - 2016

Paper No. 226-4
Presentation Time: 2:35 PM


MARTIN, Raleigh L. and KOK, Jasper F., Department of Atmospheric and Oceanic Sciences, University of California - Los Angeles, 405 Hilgard Avenue, Math Science Bldg Room 7142, Los Angeles, CA 90095,

Wind-driven sand transport generates atmospheric dust and sculpts dunes, yet models for this process generally perform poorly. An assumption underlying most aeolian saltation models is that particle speed increases with wind shear velocity, resulting in the long-established nonlinear 3/2 scaling of sand flux with wind shear stress. Here, we present comprehensive measurements from three new field sites and three published studies, showing that characteristic saltation layer heights, and thus particle speeds, remain approximately constant with shear velocity. This result implies a linear dependence of saltation flux on wind shear stress, which contrasts with the prevailing nonlinear flux law. We confirm the linear flux law with direct measurements of the stress-flux relationship occurring at each site. Models for dust generation, dune migration, and other processes driven by wind-blown sand on Earth, Mars, and several other planetary surfaces should be modified to account for linear stress-flux scaling.