Dust emission modeling for the western border region of Mexico and the USA

The border area between northwestern Mexico and the southwestern USA is composed of arid and semi-arid regions that are highly vulnerable to wind erosion. As a result, dust resuspension events take place that result in episodes of high concentrations of fine particulate matter in the atmosphere. In winter, air quality standards on both sides of the border are often exceeded. However, accurate estimates of the emission of windblown dust are rare, particularly for Mexico. In this study, emissions of particulate matter from mineral origin (dust) with an aerodynamic diameter less than 2.5 and 10 mu m (PM2.5 and PM10, respectively) were estimated for the border area for a short winter episode (January 4-12, 2006). For this purpose, a mesoscale meteorological model and a wind erosion model were used. The wind erosion model had a horizontal spatial resolution of 4 km x 4 km and a temporal resolution of 1 h. A georeferenced database of surface conditions obtained from satellite data was used in conjunction with soil parameter digital maps to generate the inputs required by the wind erosion model. The PM10 emissions for the entire domain and episode were estimated at similar to 643 g km(-2) h(-1) and the PM2.5 emissions were estimated at similar to 47 g km(-2) h(-1). The wind erosion model was subject to three sensitivity tests based on perturbation of the input surface parameters. The model output was more sensitive to changes in soil parameters (soil density and plastic pressure) than to changes in land surface data (leaf area index and fraction of vegetation cover).