Geomorphology of the Chihuahuan Desert based on potential dust emissions

Abstract

The Chihuahuan Desert of central northern Mexico and southern Arizona, New Mexico and Texas, USA, is a regionally significant dust 'hot-spot' in North America. Typical of other such hot-spots, this desert consists of a mosaic of geomorphological settings, each of which has a varying propensity for dust emission. Recently, a classification system of dust emission potential based on surface geomorphic characteristics that establishes a common framework for describing the land surface has been proposed. The classification is readily applicable to different dust source regions and designed to facilitate comparison of the relative potential dust contributions and emissivity of varying geomorphological environments in such regions.The map here (1:3,500,000) was compiled by applying the new classification to a base map of polygons from existing soil and landform maps that were produced by national government agencies. Within the study area, 11 of the 17 possible geomorphic classes were present, the most extensive being unarmoured, unincised high relief alluvial surfaces, which covered 43% of the area.As an example of how empirical dust source point data can be used with the classification, the satelliteobserved origins of dust plumes for 26 major wind erosion events from 2001 to 2009 were overlain on the map. Despite a total area of only 4%, ephemeral lakes were the source of 48% of the observed plumes. This map and the relationships derived from it provide the basis for developing equivalent maps in other dusty regions, and mark a step toward improving the representation and documentation of the strength of dust sources in numerical mineral aerosol models.

Preferential dust sources: A geomorphological classification designed for use in global dust-cycle models

“…However, each regional study tends to use different methods of data collection and compilation, different classification schemes and different mapping resolutions. These differences can be further compounded if the area of interest extends across national boundaries [e.g., Baddock et al , 2011]. This poses problems in reconciling the different data sets into a single, global data set that would be suitable for dust‐cycle modeling.…”

“…Each polygon in the base map was then assigned to one of the 17 different geomorphic sub‐classes described in Table 2 and adjacent polygons with the same geomorphic characteristics were merged with the result that the smallest polygon increased in size to 2 km 2 . Where available and appropriate, metadata provided with the base maps were used to assist with classification of land surfaces (for example wet lakes [1a]) but assignment of geomorphic characteristics was primarily achieved using the NASA Geocover mosaic created from Landsat ETM+ (at 14.5 m spatial resolution [ Tucker et al , 2004]), the authors' field knowledge, dedicated ground‐truthing sorties and published literature [ Baddock et al , 2011]. The boundaries of the geomorphic classes were fine‐tuned using these data sources which helped to improve the positional accuracy; this was especially important in areas of complicated geomorphology and where sub‐types within the scheme (e.g., lake sub‐types) were in close proximity to one another.…”

Estimating the global abundance of ground level presence of particulate matter (PM2.5)

“…Close to the Mexico/Texas border we see the elevated PM 2.5 abundance associated with the Chihuahuan Desert and the Big Bend Desert (G). Dust storms in this area often impact El Paso in Texas and Ciudad Juarez in Mexico (Rivera et al, 2010(Rivera et al, , 2009Baddock et al, 2011). The Ohio River Valley (H) encompasses several states and is home to numerous coal-fired power plants, chemical plants and industrial facilities, leading to high levels of ambient particulates (Khosah et al, 2000;Anderson et al, 2004;Yatavelli et al, 2006;Kim et al, 2007).…”

Unseen Dust Emission and Global Dust Abundance: Documenting Dust Emission from the Mojave Desert (USA) by Daily Remote Camera Imagery and Wind‐Erosion Measurements

“…Our results are relevant to the interannual relations between dust emission and climatic conditions that control regional patterns of wetness (lake inundation and flooding frequencies, for instance) and drought (Baddock et al, , ; Bryant, ; Bryant & Rainey, ; Bryant et al, ; Bullard et al, ; McTainsh et al, ; Wagner et al, ). Along these lines, Zender and Kwon () examined temporal relations between climate anomalies and atmospheric dust loading from 14 global dust‐source areas.…”