EXAMINING THE SENSITIVITY OF SURFACE ROUGHNESS CORRECTION IN DUST EMISSION MEASUREMENTS AT WHITE SANDS NATIONAL PARK, NM USING A NEW LANDFORM LOOKUP TABLE APPROACH

Uncertainties in field-based dust emissivity measurements negatively impact dust budgets estimated from regional dust emission models. White Sands National Park (WSNP), located in central New Mexico, hosts a notable dust emission hotspot and serves as a prime example for which modeling uncertainties may significantly affect our ability to forecast emission potentials to the atmosphere. We evaluate a new landform-based lookup table approach in this study to enable systematic corrections to surface roughness, a significant source of uncertainty when characterizing dust emissivity. We used a dataset collected at WSNP to evaluate the sensitivity of surface roughness and to quantify uncertainty in dust emissivity as a result of variations in this parameter. Prior studies have characterized dust emission potential on a variety of landforms at WSNP using the Portable In-Situ Wind Erosion Laboratory (PI-SWERL), which resulted in an estimated annual dust flux of 277 tons/km²/yr from sand sheets alone, demonstrating the significance of sand sheets as notable emitters in the region. However, accepted methodologies for assigning the surface roughness coefficient (α) lack quantitative constraints. Recent work has refined this approach using an alternative method of quantifying α from photogrammetric reconstructions of field surfaces from within WSNP. These measurements of α were compiled into a site-specific lookup table which was used to reassign the α values from previous studies by visual comparison to field photographs of PI-SWERL sites. This approach provided a comparable and reproducible dataset that contains adjusted α values used for direct comparison of the two methods. Statistical comparisons of resulting dust emissivity between landforms for which α was adjusted indicate that geometric means for sand sheets were significantly impacted at high shear velocities (≥0.70 m/s), while the other landforms showed insignificant changes. The impact of surface roughness adjustments resulted in an increased annual dust flux budget by nearly 20% for sand sheets alone. Our analysis of the sensitivity in assigning α quantifies a potentially significant source of methodologic error, which will ultimately increase the accuracy of future dust emission studies when site-specific landform lookup table can be developed.