|Van Pelt, Robert - Scott|
Submitted to: International Workshop on Mineral Dust
Publication Type: Abstract Only
Publication Acceptance Date: 7/3/2003
Publication Date: 9/10/2003
Citation: Zobeck, T.M., Van Pelt, R.S., Kjelgaard, J., Sharratt, B.S. 2003. Linkage of saltation and dust emissions in bare agricultural fields. International Workshop on Mineral Dust.
Technical Abstract: Knowledge of vertical dust emission and flux is needed to develop and validate estimates predicted in wind erosion and aerosol dispersion models. Vertical dust flux is often estimated using a gradient method and flux equation. In addition, wind tunnel studies and theoretical considerations show that the dust (<20 'm) emission rate is proportional to the horizontal saltation flux, and hence proportional to the cube of the friction velocity. These results were generally based on time-integrated measurements of dust flux. Recent advances in sensor technology have allowed for the measurement of wind velocity measurements and saltation and dust fluxes at high frequency, enabling more detailed analyses of the interaction of wind, saltation, and dust. This presentation will report the results from two field dust sampling campaigns, conducted on agricultural fields in the US, that employed fast-response wind, saltation, and dust sensors. One site (WA) was located on a silt loam soil in the northwest US and the second site (TX) was located on a fine sandy loam soil in the Southern High Plains of west Texas, regions of extensive aeolian deposits. Sampling equipment deployed included BSNE saltation samplers, Sensit saltation monitors, sonic anemometers at two heights, tapered element oscillating microbalances (TEOMs), Dusttrak aerosol monitors, high volume dust samplers, and standard meteorological equipment. Temporal resolution of saltation and dust sampling equipment varied with the type of samplers. Horizontal saltation flux measured with BSNE showed good correlation with PM10 measured over the same time period. Dust concentration with height varied with storm intensity. Dust concentrations were similar at different heights during intense storms but seemed to vary more with height during less intense HWE. Evidence for the saltation effects on dust flux varied with soil. Strong evidence for a saltation effect on dust flux was found in the fine sandy loam TX site. Conversely, few saltation particle impacts were observed during HWEs on the silt loam WA site and an aerodynamic analysis based on wind velocity profile regression also suggested little saltation occurred during HWEs.