| WRAP Dust Assessment
Identification of Source Areas Affecting Dust Concentrations
The goal of the work was to identify the source areas that contribute to elevated dust concentrations during the worst dust days over the period 2001-2003 at Salt Creek and White Mountain Wilderness areas in New Mexico. Since windblown dust emissions inventories are not widely available and are notoriously inaccurate, the USGS wind erosion group (WEG) index classification was used as a surrogate to identify geographic areas that are susceptible to wind erosion and serve as likely sources of windblown dust under appropriate meteorological conditions, i.e. high wind speeds. The WEG index ranges from 1 (Very fine sand, fine sand, sand or coarse sand susceptible to wind erosion) to 8 (Soils not susceptible to wind erosion). The WEG index was transformed to a dust emission potential (DEP) which has the property of having values that range between 0 (no erodible) and 1 (highly erodible). To estimate wind conditions over areas where surface meteorological data were not available, DRI utilized 2-day backwards air mass trajectories (back-trajectories) for Salt Creek and White Mountain, calculated every 3 hours at 500-m starting height using the NOAA HYSPLIT trajectory model (Draxler and Hess, 1997) with the Eta Data Assimilation System (EDAS) meteorological data as inputs. Trajectory points associated with worst dust days that exhibited speeds higher than the threshold value were integrated using the Kernel-type spatial probability density normalized by the total number of trajectory points for all worst dust days. For regions located in New Mexico and surrounding states that are potential sources of windblown dust during the 2001-2003 worst dust days, the products of the DEP index and back-trajectory threshold probability index will be calculated. Because both parameters are normalized (i.e. range from 0 to 1), the product provided an index of windblown dust influence (WDI) (also from 0 to 1). WDI does not provide a direct source attribution for windblown dust, it does highlight the source areas that are likely to exert the greatest influence on the Salt Creek and White Mountain Class I areas. The effect of dilution was qualitatively accounted for by dividing the WDI by the distance between the source area and the receptor.
at Salt Creek and White Mountain Wilderness Areas in New Mexico
Page updated 20 Feb 2006