Dr. Raleigh Martin has been awarded an NSF Earth Sciences Postdoctoral Fellowship to carry out a research and education plan at the University of California, Los Angeles. He will investigate the process of sand transport in response to turbulent winds in natural desert and beach environments. This sand transport forms sand dunes, and the bombardment of desert soils by bouncing sand produces dust storms. It is therefore important to be able to predict how the rate of sand transport is related to the speed of blowing wind. Existing theory provides reasonable predictions for sand transport under constant winds, but these predictions break down under the turbulent, rapidly-fluctuating wind conditions characteristic of natural environments. Changes in the rate of sand transport both lag and feed back onto changes in wind speed near the ground surface. Through theoretical reasoning supported by field observations, this project will quantify these complex interactions between fluctuating sand transport and turbulent winds, with the ultimate goal of improving predictions of sand transport in natural environments. The project will proceed from the bottom up, beginning with a detailed analysis of wind-sand interactions, leading into development of a new model for wind-blown sand, and culminating in a linkage of this model to descriptions of turbulent winds in natural environments. Development and validation of the wind-blown sand model will be based on coupled high-resolution measurements of wind speed and sand transport in natural environments. In addition to advancing our understanding of a basic process that shapes deserts and coastal environments, this work will provide the basis for addressing such issues as dust pollution, coastal protection, and agricultural soil erosion. Research efforts will be coupled to initiatives to improve the public availability and accessibility of research data. Furthermore, educational outreach will be fostered through development of hands-on earth science projects for fifth-grade students at a local elementary school.
