reference : Sources of carbonaceous aerosols over the United States and implications for natural visibility

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/reference/a1a1caa5-a3b6-4dd1-aef3-396aebc8cfed
Bibliographic fields
reftype Journal Article
Abstract We use a global three-dimensional model (GEOS-CHEM) to better quantify the sources of elemental carbon (EC) and organic carbon (OC) aerosols in the United States through simulation of year-round observations for 1998 at a network of 45 sites (Interagency Monitoring of Protected Visual Environments (IMPROVE)). Simulation with our best a priori understanding of sources, including global satellite data to constrain fire emissions, captures most of the variance in the observations (R super 2 = 0.84 for EC, 0.67 for OC) with a low bias of 15 percent for EC and 26 percent for OC. Multiple linear regression to fit the IMPROVE data yields best estimates of 1998 U.S. sources of 0.60 Tg year super -1 EC and 0.52 Tg year super -1 OC from fossil fuel; 0.07 Tg year super -1 EC and 0.89 Tg year super -1 OC from biofuel; 0.08 Tg year super -1 EC and 0.60 Tg year super -1 OC from wildfires; and 1.10 Tg year super -1 OC from vegetation. We find that fires in Mexico and Canada contributed 40-70 percent of annual mean natural EC in the United States for 1998 and 20-30 percent of annual mean natural OC. Transpacific transport from Asian pollution sources amounted to less than 10 percent of the natural EC and less than 2 percent of the natural OC; in contrast to ozone, we find that intercontinental transport of anthropogenic carbonaceous aerosols does not enhance significantly the natural background. IMPROVE observations and model simulations for the summer of 1995 show that Canadian fire emissions can produce large events of elevated EC and OC in the southeastern United States. Our best estimates of mean natural concentrations of EC and OC in the United States, using a model simulation with climatological monthly mean fire emissions, are 2-3 times higher than the default values recommended by the U.S. Environmental Protection Agency for visibility calculations, except for OC in the eastern United States (16 percent lower).
Author Park, R.J., D.J. Jacob, M. Chin, and R.V. Martin
DOI 10.1029/2002JD003190
ISSN 0148-0227
Issue D12
Journal Journal of Geophysical Research
Pages 4355
Title Sources of carbonaceous aerosols over the United States and implications for natural visibility
Volume 108
Year 2003
Bibliographic identifiers
.reference_type 0
_record_number 18909
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