Environmental Engineering Reference
In-Depth Information
2. Method
The 2004 regional scale simulation was performed using the CMAQ model
version 4.7 (Byun and Schere, 2006) instrumented with the decoupled direct
method in three dimensions (DDM-3D) (Napelenok et al., 2008). Standard model
configuration was used including the inverse donor-cell advection scheme, eddy
diffusion, saprc99 chemical mechanism, and asymmetric convective cloud
module. Regional meteorology was processed using MM5, and emissions were
processed using SMOKE based on the National Emission Inventory (2002 NEI).
Two emissions scenarios were considered and compared: one using a standard
emissions inventory; and one with only “natural” emissions sources. The biogenic
sources included processes such as volatile organic compounds (VOCs) emissions
from plants, nitrogen oxide (NO) emissions from soil, various compounds from
wildfires, etc. Emissions from prescribed non-agricultural burning are also included
in the PRB calculation, because these are used for land management to prevent
more devastating wildfires.
Fig. 1. Regional PM 2.5 concentrations in January and August, 2004 for base case, PRB, and the
influence from the boundary for each region
To account for the influence of long-range transport on background PM 2.5
concentrations, the global chemical transport model, GEOS-Chem version 7-04-
11, was used to provide hourly lateral boundary conditions for the full simulation
 
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