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Examining single-source secondary impacts estimated from brute-force, decoupled direct method, and advanced plume treatment approaches
Citation:
Kelly, J., K. Baker, S. Napelenok, AND S. Roselle. Examining single-source secondary impacts estimated from brute-force, decoupled direct method, and advanced plume treatment approaches. ATMOSPHERIC ENVIRONMENT. Elsevier Science Ltd, New York, NY, 111:10-19, (2015).
Impact/Purpose:
The National Exposure Research Laboratory’s Atmospheric Modeling Division (AMAD) conducts research in support of EPA’s mission to protect human health and the environment. AMAD’s research program is engaged in developing and evaluating predictive atmospheric models on all spatial and temporal scales for forecasting the Nation’s air quality and for assessing changes in air quality and air pollutant exposures, as affected by changes in ecosystem management and regulatory decisions. AMAD is responsible for providing a sound scientific and technical basis for regulatory policies based on air quality models to improve ambient air quality. The models developed by AMAD are being used by EPA, NOAA, and the air pollution community in understanding and forecasting not only the magnitude of the air pollution problem, but also in developing emission control policies and regulations for air quality improvements.
Description:
In regulatory assessments, there is a need for reliable estimates of the impacts of precursor emissions from individual sources on secondary PM2.5 (particulate matter with aerodynamic diameter less than 2.5 microns) and ozone. Three potential methods for estimating these impacts using Eulerian grid photochemical models are the brute-force (B-F) method, the decoupled direct method (DDM), and advanced plume treatment (APT). Here, we systematically inter-compare and assess the B-F, DDM, and APT approaches using hypothetical sources in a consistent modeling platform for a wide range of source conditions (i.e., emissions amount and composition, location, and stack parameters). Overall, there is consistency in the impacts of NOx and VOC sources on ozone and SO2 sources on PM2.5 sulfate calculated by these methods. The consistency is evident in the similar magnitudes, spatial patterns, and strong correlations among the impacts. Some disagreement among methods is evident in the PM2.5 nitrate impacts associated with NH3 and NOx sources. Numerical instabilities in DDM sensitivity calculations appear to compromise the nitrate impact estimates for that approach. The B-F and APT nitrate impacts also appear to have been affected by numerical errors to a lesser degree than DDM, with the errors being more prominent for APT than B-F. Primary PM2.5 impacts calculated with the B-F and DDM approaches for primary PM2.5 sources agreed closely, but sometimes differed from impacts calculated with APT. Our results suggest that primary pollutant impacts are more sensitive to differences in near-source mixing and transport between the Eulerian grid and plume-in-grid approaches than are secondary pollutant impacts.
URLs/Downloads:
REVISED KELLY_SINGLESOURCE_FINAL.PDF (PDF, NA pp, 876.575 KB, about PDF)Atmospheric Environment
