Long-term trends in spring season land surface roughness and its relationship to vegetation cover chance across the southwestern united states

Authors: DHITAL, SAROJ - New Mexico State University; Webb, Nicholas - Nick; CHAPPELL, ADRIAN - Cardiff University; McCord, Sarah; TYREE, GAYLE - Us Geological Survey (USGS); NAUMAN, TRAVIS - Natural Resources Conservation Service (NRCS, USDA); DUNIWAY, MICHAEL - Us Geological Survey; LEGRAND, SANDRA - Us Army Engineer Research And Dvelopment Center; LETCHER, THEODORE - Us Army Engineer Research And Dvelopment Center; SKILES, MCKENZIE - University Of Utah; NAPLE, PATRICK - University Of Utah; CHANEY, NATHANIEL - Duke University; CAI, JIAXUAN - Duke University

Submitted to: International Conference on Aeolian Research
Publication Type: Abstract Only
Publication Acceptance Date: 5/1/2023
Publication Date: 7/14/2023
Citation: Dhital, S., Webb, N.P., Chappell, A., McCord, S.E., Tyree, G., Nauman, T., Duniway, M., LeGrand, S., Letcher, T., Skiles, M., Naple, P., Chaney, N., Cai, J. 2023. Long-term trends in spring season land surface roughness and its relationship to vegetation cover chance across the southwestern united states. International Conference on Aeolian Research. Abstract.

Interpretive Summary: Increasing spring (March-May) dust activity across the southwestern United States is a risk factor for human health, the natural ecosystem, and water resources in the Colorado River Basin. These risks could increase with the combined effects of climate change and current land use practices across the southwest. In this study, we applied a recently developed remote sensing technique and investigated the long-term and decadal change in land surface roughness and vegetation cover across the southwest using 20 years of datasets from the Moderate Resolution Imaging Spectroradiometer and Rangeland Analysis Platform. Our results enable the identification of regions with changes in springtime land surface roughness and its links to vegetation change during the past two decades.

Technical Abstract: Increasing springtime (March-May) dust activity across the southwestern United States is a risk factor for human health, ecosystems, and water resources in the Colorado River Basin. These risks could increase as climate change and land uses interactively accelerate land cover change within dust source areas. Understanding the influence of climate and land cover change on springtime dust emission and deposition requires a spatiotemporal assessment of land surface roughness. We analyzed recent trends in land surface roughness and vegetation cover and their relationships to assess the amount and drivers of change in land cover within southwest US dust source areas. We used an established albedo-based roughness model to calculate us*/Uh using 20 years (2001-2020) of MODIS daily albedo and vegetation functional group cover datasets from the Rangeland Analysis Platform (both rescaled to 4 km) to calculate decadal and long-term trends using the Mann-Kendall trend test. We then examined correlations between surface roughness and vegetation cover to elucidate the contributions of annual and perennial herbaceous and woody vegetation change to roughness trends. Our results identify where springtime surface roughness is changing and where those trends are linked to vegetation change. The trends in surface roughness and vegetation cover provide insights needed to predict future vegetation dynamics and active dust sources. The study highlights how the albedo-based roughness model can be used to monitor land surface roughness change and identify how ecosystem changes contribute to change in surface roughness, which provides a direct link to dust mitigation and land management practices.