Friction between air and a ground surface affects both the velocity of winds and the configuration of materials on the ground. The higher winds are above the surface, the less their velocities are retarded by surface friction. The height above the surface at which surface friction ceases to affect wind velocities is its aerodynamic roughness length, but this height varies in relation to the nature and configuration of surface materials. This doctoral dissertation project will examine the spatial variation of the aerodynamic roughness length as measured over natural terrains, and it will develop a tool to predict the aerodynamic roughness length by remote sensing. Field data will be obtained under natural conditions: the aerodynamic roughness length will be derived from wind profiles corrected for atmospheric stability. The topographic surface roughness will be measured in the field using a variety of methods to assess both micro-topography and the overall topography. The relationship between variations in wind veolcities and the aerodynamic roughness length will be studied using traps that capture airborne sediment. The project also will examine means of analyzing aerial radar images for several wavelengths and polarizations to determine their utility in estimating aerodynamic roughness. This project will provide valuable information about the aerodynamic roughness length and thus about wind activity that affects erosion processes, desertification, and the nature of windblown sands. In addition, greater knowledge about the aerodynamic roughness length will contribute significantly to the refinement of global and regional climatic models. This project also will provide an excellent opportunity for a promising young scholar to continue to develop independent research skills.
