Drought affects the occurrence and intensity of aeolian dust events in many ecoregions. This study investigated the effects of "drought legacy" (the cumulative temporal persistence of drought's consequences on the earth system) on dust generation, a topic which had not previously been evaluated. We investigated the potential dust/drought legacy relationship in the USA's Southern Great Plains and Chihuahuan Desert ecoregions over 14 years, including the 2011-2012 extreme drought, at spatial distances up to 100 km around dust point sources and for up to 5 years' drought history. At every temporal and spatial scale, drought levels associated with dust initiation points in the two ecoregions were significantly different. Chihuahuan Desert dust sources concentrated in areas of severe to extreme drought, while those in the Southern Great Plains, which experiences greater land use, spanned wider ranges of drought conditions. At short temporal scales of drought (1 week and 1 year), dust initiation in the Chihuahuan Desert was associated strongly with severe to exceptional drought conditions at all spatial extents, while Southern Great Plains dust sources were linked to lower drought intensities. For longer drought histories (the past 2 and 5 years), Chihuahuan Desert dust sources were connected with moderate to severe drought, while Southern Great Plains dust sources were linked to moderate drought, at all spatial extents. Drought's legacies, extending over multiple years and kilometer scales, are shown to have roles in subsequent dust events at regional scales, though they can be regionally modulated by land use practices and ecosystem characteristics.

Ephemeral lakebeds, common features in semiarid and arid regions, are often potent sources of atmospheric dust. One such ephemeral lake in southwestern New Mexico, USA, Lordsburg Playa, is transected by Interstate 10 (I-10), a major transportation artery crossing the southern US. Since construction of I-10 in the 1960s, at least 45 people have perished in motor vehicle crashes at Lordsburg Playa caused by dust-associated loss of visibility. The rate of visibility reductions from dust and traffic crash deaths has increased as climate change has resulted in persistent drought in this region. We used ground-based measurements creating dust emissions from increasing levels of shear stress via a Portable In-Situ Wind ERosion Laboratory (PI-SWERL) to test natural and disturbed surfaces. These tests assessed the potential dust emissivities of different sediment surfaces and landscape positions along with the effects of surface disturbance by anthropogenic activities. We also investigated the evolution of the playa and surrounding landscapes using 35 years of remotely sensed images from the Landsat 5 and Landsat 8 satellites and a shorter time period for the higher spatial resolution images from the Sentinel-2 satellite using spectral unmixing to separate the relative contributions of bare soil, water, and vegetation endmembers from the spectral reflectance of individual pixels. Interferometric techniques were applied to data obtained from Synthetic Aperture Radar instrumentation aboard the Sentinel-1 satellite to develop digital elevation maps for the playa and surrounding landscapes. Finally, we used process-based models to simulate wind erosion, resulting PM10 emissions (SWEEP), and plume transport (AERMOD) from a dust source immediately adjacent to and often upwind of the highway. We found that natural surfaces in the playa basin were highly variable with respect to their potential dust emissivities. Beach deposits along the eastern and particularly western margins of the lakebed were the most highly emissive, followed by soils in the Animas Creek Delta south of the lakebed which were in turn much more emissive than the indurate sediments of the lakebed floor and similar buried lakebed sediments. Further, disturbance of the soil surface in the delta sediments resulted in order of magnitude increase in dust emissions. Analysis of the remote sensing images revealed annual and seasonal differences in the proportion of the bare soil, vegetation, and water endmembers present on the playa lakebed and surrounding landscapes. The bare soil endmember was greatest during the spring and in years with less than average rainfall. In many cases, these drought-affected years aligned temporally with the increased frequency of dust events and fatalities from motor vehicle crashes. The summer monsoon season generally resulted in an increase of the water endmember in the lakebed and in increases of the vegetation endmember on the delta sediments and uplands surrounding the playa. Years with more water surface coverage in the lakebed and greater vegetation coverage tended to have less frequent dust events. Modelling using SWEEP to simulate wind erosion and dust entrainment and AERMOD to simulate transport and dispersal of the resulting dust plume agreed well with visual images obtained with cameras adjacent to the modelled source area and a nearby New Mexico Department of Transportation meteorological tower.

Lordsburg Playa, a dry lakebed in the Chihuahuan Desert of southwestern New Mexico (USA), is crossed by Interstate Highway 10 (I-10). Dust from the playa threatens highway safety and has caused dozens of fatal accidents. Two numerical models-the U.S. Department of Agriculture's Single-Event Wind Erosion Evaluation Program (SWEEP) and the American Meteorological Society and U.S. Environmental Protection Agency Regulatory Model (AERMOD)-were used to simulate and predict the generation and dispersion of windblown soil, dust, and PM10 from playa hotspots and estimate PM10 concentrations downwind. SWEEP simulates soil loss and particulate matter emissions from the playa surface, and AERMOD predicts the concentration of transported dust. The modeling was informed by field and laboratory data on Lordsburg Playa's properties, soil and land use/land cover databases, and weather data from meteorological stations. The integrated models predicted that dust plumes originating on the playa-including a large, highly emissive area away from the highway and a smaller, less emissive site directly upwind of the interstate-can lead to hourly average PM10 concentrations of tens, to hundreds of thousands, of micrograms per cubic meter. Modeling results were consistent with observations from webcam photos and visibility records from the meteorological sites. Lordsburg Playa sediment contains metals, as will its dust, but human exposures will be short-term and infrequent. This study was the first to successfully combine the SWEEP wind erosion model and the AERMOD air dispersion model to evaluate PM10 dispersion by wind erosion in a playa environment. With this information, land managers will be able to understand the potential levels of dust and PM10 exposure along the highway, and better manage human health and safety during conditions of blowing dust and sand at Lordsburg Playa.

Driven by erodible soil, hydrological stresses, land use/land cover (LULC) changes, and meteorological parameters, windblown dust events initiated from Lordsburg Playa, New Mexico, United States, threaten public safety and health through low visibility and exposure to dust emissions. Combining optical and radar satellite imagery products can provide invaluable benefits in characterizing surface properties of desert playas—a potent landform for wind erosion. The optical images provide a long-term data record, while radar images can observe land surface irrespective of clouds, darkness, and precipitation. As a home for optical and radar imagery, powerful algorithms, cloud computing infrastructure, and application programming interface applications, Google Earth Engine (GEE) is an invaluable resource facilitating acquisition, processing, and analysis. In this study, the fractional abundance of soil, vegetation, and water endmembers were determined from pixel mixtures using the linear spectral unmixing model in GEE for Lordsburg Playa. For this approach, Landsat 5 and 8 images at 30 m spatial resolution and Sentinel-2 images at 10–20 m spatial resolution were used. Employing the Interferometric Synthetic Aperture Radar (InSAR) techniques, the playa’s land surface changes and possible sinks for sediment loading from the surrounding catchment area were identified. In this data recipe, a pair of Sentinel-1 images bracketing a monsoon day with high rainfall and a pair of images representing spring (dry, windy) and monsoon seasons were used. The combination of optical and radar images significantly improved the effort to identify long-term changes in the playa and locations within the playa susceptible to hydrological stresses and LULC changes. The linear spectral unmixing algorithm addressed the limitation of Landsat and Sentinel-2 images related to their moderate spatial resolutions. The application of GEE facilitated the study by minimizing the time required for acquisition, processing, and analysis of images, and storage required for the big satellite data.

Recent observations reveal that dust storms are increasing in the western USA, posing imminent risks to public health, safety, and the economy. Much of the observational evidence has been obtained from ground-based platforms and the visual interpretation of satellite imagery from limited regions. Comprehensive satellite-based observations of long-term aerosol records are still lacking. In an effort to develop such a satellite aerosol dataset, we compared and evaluated the Aerosol Optical Depth (AOD) from Deep Blue (DB) and Dark Target (DT) product collection 6.1 with the Aerosol Robotic Network (AERONET) program in the western USA. We examined the seasonal and monthly average number of Moderate Resolution Imaging Spectroradiometer (MODIS) Aqua DB AOD retrievals per 0.1∘ × 0.1∘ from January 2003 to December 2017 across the region’s different topographic, climatic, and land cover conditions. The number of retrievals in the southwest United States was on average greater than 37 days per 90 days for all seasons except summer. Springtime saw the highest number of AOD retrievals across the southwest, consistent with the peak season for synoptic-scale dust events. The majority of Arizona, New Mexico, and western Texas showed the lowest number of retrievals during the monsoon season. The majority of collocating domains of AOD from the Aqua sensor showed a better correlation with AERONET AOD than AOD from Terra, and the correlation coefficients exhibited large regional variability across the study area. The correlation coefficient between the couplings Aqua DB AOD-AERONET AOD and Terra DB AOD-AERONET AOD ranges from 0.1 to 0.94 and 0.001 to 0.94, respectively. In the majority of the sites that exhibited less than a 0.6 correlation coefficient and few matched data points at the nearest single pixel, the correlations gradually improved when the spatial domain increased to a 50 km × 50 km box averaging domain. In general, the majority of the stations revealed significant correlation between MODIS and AERONET AOD at all spatiotemporal aggregating domains, although MODIS generally overestimated AOD compared to AERONET. However, the correlation coefficient in the southwest United States was the lowest and in stations from a higher latitude was the highest. The difference in the brightness of the land surface and the latitudinal differences in the aerosol inputs from the forest fires and solar zenith angles are some of the factors that manifested the latitudinal correlation differences.

Ephemeral lakes (playas) at the termination of drainages are a common feature of drylands. When dry, playa sediments can be highly wind-erodible, becoming potent local and regional sources of dust and PM 10 , airborne particles with diameters less than 10 µm, causing potentially sudden loss of visibility to travelers on downwind roadways. Lordsburg Playa, in southwestern New Mexico, USA is bisected by Interstate Highway 10. Dust storms emanating from the playa have been responsible for numerous visibility-related road closures (including 39 road closures between 2012- 2019) causing major economic losses, as well as hundreds of dust-related vehicle crashes, causing 41 lost lives in the last 53 years. We investigated the critical wind friction velocity thresholds and the dust emissivities of surfaces representing areas typical of Lordsburg Playa’s stream deltas, shorelines, and ephemerally flooded lakebed using a Portable In-Situ Wind ERosion Laboratory (PI-SWERL). Mean threshold friction velocities for PM 10 entrainment ranged from less than 0.30 m s -1 for areas in the delta and shoreline to greater than 0.55 m s -1 for ephemerally flooded areas of the lakebed. Similarly, we quantified mean PM 10 vertical flux rates ranging from less than 500 µ g m -2 s -1 for ephemerally flooded areas of lakebed to nearly 25,000 µg m -2 s -1 for disturbed delta surfaces. The apparently unlimited PM 10 supply of the relatively coarse sediments along the western shoreline however is problematic and indicates that this may be the source area for longer-term visibility limiting dust events and should be a focus area for dust mitigation efforts.

Earth and Space Science Open Archive posterOpen AccessYou are viewing the latest version by default [v1]Investigating the Surface Properties and Evolution of a Desert Playa Using Optical and Radar Satellite Imagery ProductsAuthors Iyasu Eibedingil iD Daniel Tong iD Thomas Gill iDSee all authors Iyasu EibedingiliDCorresponding AuthorUniversity of Texas at El PasoiDhttps://orcid.org/0000-0003-2649-5374view email addressThe email was not providedcopy email addressDaniel TongiDGeorge Mason University Foundation Inc.iDhttps://orcid.org/0000-0002-4255-4568view email addressThe email was not providedcopy email addressThomas GilliDUniversity of Texas at El PasoiDhttps://orcid.org/0000-0001-9011-4105view email addressThe email was not providedcopy email address