Relative impact of windblown dust versus anthropogenic fugitive dust in PM2.5 on air quality in North America

Abstract

A new windblown dust emissions module was recently implemented into A Unified Regional Air Quality Modeling System (AURAMS), a Canadian regional air quality model, to investigate the relative impact of windblown dust versus anthropogenic fugitive dust on air quality in North America. In order to apply the windblown dust emissions module to the entire North American continent, a soil grain size distribution map was developed using the outputs of 4 monthly runs of AURAMS for 2002 and available PM2.5 dust content observations. The simulation results using the new soil grain size distribution map showed that inclusion of windblown dust emissions is essential to predict the impact of dust aerosols on air quality in North America, especially in the western United States. The windblown dust emissions varied widely by season, whereas the anthropogenic fugitive dust emissions did not change significantly. In the spring (April), the continental monthly average emissions rate of windblown dust (4.1 × 107 kg/d) was much higher than that of anthropogenic fugitive dust (1.5 × 107 kg/d). The total amount of windblown dust emissions in North America predicted by the model for 2002 was comparable to that of anthropogenic fugitive dust emissions. Even with the inclusion of windblown dust emissions, however, the model still had difficulty simulating dust concentrations. Further improvements are needed, in terms of both limitations of the windblown dust emission module and uncertainties in the anthropogenic fugitive dust emissions inventories, for improved dust modeling. Copyright 2010 by the American Geophysical Union.