Source characteristics of hazardous Chihuahuan Desert dust outbreaks

The Chihuahuan Desert region is an important contributor to atmospheric dust loading and transport in North America; however, specific dust sources in this region are poorly characterized. Major dust events frequently are characterized by multiple dust plumes developing nearly simultaneously over a large region. Remote sensing data were used to identify the source locations and associated land cover for the most extreme dust events in the Chihuahuan Desert since 2002. Analysis of infrared channels utilizing brightness temperature differences was used to analyze data from geostationary and polar-orbiting satellites, from which dust sources were determined and located. This methodology was applied to the five dust events in the region that resulted in “hazardous” PM10 levels in Texas per the USEPA’s Air Quality Index. Source locations determined from satellite images were used in conjunction with LANDSAT data and Google Earth™ images to determine the corresponding land-surface features. Agricultural lands, playas, and their edges are pointed out as focus areas for dust emission, at least during the most intense events. The 130 dust plume initiation sites were relatively uniformly spaced over the landscape, not clumped into a few “hotspots,” suggesting the role of spatiotemporally random meteorological factors in determining major points of emission within and between dust storms. These findings provide an initial characterization of Chihuahuan Desert dust source locations and establish a baseline for continued research in determining potential locations for future dust outbreaks in the southwestern U.S. and northwestern Mexico.