|Van Pelt, Robert - Scott|
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 9/3/2004
Publication Date: 9/14/2004
Citation: Zobeck, T.M., Van Pelt, R.S. 2004. Correlation of saltation and suspended dust flux[ABSTRACT]. INTERNATIONAL SYMPOSIUM ON SAND AND DUST STORM.
Technical Abstract: Strong atmospheric winds may cause wind erosion and dust emissions on bare, dry, erodible fields. Knowledge of vertical suspended 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 and field studies and theoretical considerations show that the dust (<20 microns) emission rate is proportional to the horizontal saltation flux. These results were generally based on time-integrated measurements of dust flux (for example, a per-storm basis). 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 linkage of wind, saltation, and suspended dust. This presentation will report the results from a field dust sampling project conducted on a fine sandy loam soil in the Southern High Plains of west Texas, a region a significant wind erosion. Measurements of climatic variables and airborne sediment mass and concentration were made during three strong wind events in 2003. The study employed fast-response wind, saltation, and dust sensors including BSNE saltation samplers, SENSIT saltation monitors, Dusttrak aerosol monitors, and standard meteorological equipment. Dust concentration varied with height, sampling location and storm intensity, and was highly correlated with saltation. Specifically, horizontal saltation flux measured with BSNE (time-integrated) samplers showed good correlation with suspended dust measured over the same time period. This study clearly shows that vertical dust flux estimates were very sensitive to dust concentration measurement height and proximity to the dust source. Vertical dust flux values estimated between heights of 2m to 5m were 2 to 5 times those estimated between heights of 5m to 10m. Tower placement in relation to the upwind unerodible boundary produced significant differences in vertical dust flux that varied with storm intensity. During the most intense storm event, the vertical dust flux between heights of 2m to 5m measured at the tower 200m from the unerodible boundary was almost 2.5 times as that measured at the tower 100m from the unerodible boundary. Vertical dust flux was closely related with horizontal sediment flux only when the winds came from the same direction during the entire duration of horizontal sediment flux measurements.