A cross-comparison of threshold friction velocities for PM10 emissions between a traditional portable straight-line wind tunnel and PI-SWERL

Abstract

Experiments in large wind tunnels have made vital contributions to our knowledge of aeolian processes. However, the size of these instruments makes them impractical for field application. To facilitate field measurements on the dust emission potential of soils, the Portable In-Situ Wind Erosion Lab (PI-SWERL) was developed. Previous research shows that the PI-SWERL can be used to quantify dust emission potentials and (threshold) friction velocities. Studies that compare the PI-SWERL to traditional wind tunnels mainly focus on the dust emission potential at various friction velocities. In the present study, we quantified the threshold friction velocity for PM 10 emission using a PI-SWERL and compare it to results obtained with a straight-line wind tunnel: the Portable Wind and Rainfall Simulator of the University of Basel (PWRS). Tests were performed on two types of substrate: fine sand (NS1) and loamy sand (DS1). For NS1, a threshold friction velocity of 0.33 m s − 1 was identified from both the PI-SWERL and the PWRS data. For DS1, identified threshold friction velocities showed differences: 0.25 m s − 1 by the PI-SWERL and 0.39 m s − 1 by the PWRS. The position of the DustTrak II monitor's inlet tube and variations of the fan's speed by different operators could explain the difference in identified thresholds. Although different threshold friction velocities were obtained for one of the substrates, we believe that comparable results can be achieved by adjusting the experimental design in future research. Therefore, the PI-SWERL can be successfully used to quantify thresholds, facilitating dust emission studies in more remote regions.

Emission of Fine Dust from Open Storage of Industrial Materials Exposed to Wind Erosion

“…The probabilistic approach, as alternative to the empirical algorithms already proposed by the technical and scientific literature [9][10][11][12][13][14][15][16][17]; -…”

The Influence of Drying on the Aeolian Transport of River‐Sourced Sand

“…Van Leeuwen et al. (2021) compared u * t measured with the PI‐SWERL and a straight‐line wind tunnel on fine sand and loamy sand; they determined nearly exact correspondence between methods for the fine sand surface, which is similar in texture to the sandy surfaces we studied, but not the loamy sand which consisted of more small dust‐sized particles.…”

“…Etyemezian et al (2007) developed the PI-SWERL to measure dust emission potential of soil surfaces, specifically the vertical flux of PM10 dust emitted from the surface as a function of shear stress or u * . Many researchers have since demonstrated that the dust flux and associated threshold values of u * can be estimated from the time series of u * and PM10 concentration data acquired during an individual PI-SWERL measurement test (Etyemezian et al, 2019;Fick et al, 2020;Sankey et al, 2012;Sweeney et al, 2008Sweeney et al, , 2011Sweeney et al, , 2019van Leeuwen et al, 2021;von Holdt et al, 2019). We used the PI-SWERL instrument instead of a portable in-line wind tunnel for logistical reasons: the non-invasive nature of the PI-SWERL owing to its small size, quiet operation, and the ability to transport the instrument directly to each measurement location without a vehicle satisfied Grand Canyon National Park's monitoring and research permitting requirements to use the available tool that imparts the minimum impact on the wilderness qualities of the park.…”