Thesis
Aerosol and ozone sensitivity analysis with the community multi-scale air quality (CMAQ) model for the Pacific Northwest
Washington State University
Master of Science (MS), Washington State University
2002
Handle:
https://hdl.handle.net/2376/89
Abstract
The CMAQ model was applied to investigate the sensitivity of PM2.5 and ozone to changes in precursor emissions in the Pacific Northwest. The simulation results showed that different regions responded differently to changes in emissions species. For PM2.5 changes with precursor emissions, the responses were explained by the region's total ammonia to sulfate molar ratio. Enumclaw, WA, had a high ratio, its PM2.5 concentrations were highly sensitive to NOx and NH3 emissions, but insensitive to SO2 emissions change. In areas that had low ratios, such as, Carus, OR and the Columbia River Gorge, OR, PM2.5 concentrations were highly sensitive to changes in SO2 emissions, but insensitive to NOx and NH3 changes. The results also demonstrated the coupled chemistry between aerosol and ozone in the atmosphere. High ozone concentrations led to higher atmospheric oxidant production, which in turn, increased aerosol formation. These interactions led to decreases in PM2.5 formation with increased in NOx emission, as ozone was titrated by the increased NO emissions. In terms of ozone sensitivity towards VOC and NOx emissions changes, ozone changed linearly in all areas with combined NOx and VOC (NOx&VOC), anthropogenic VOCs and biogenic VOCs. The sensitivity was stronger in urban regions than rural sites. However, when NOx emission was changed alone, ozone changed non-linearly in urban regions, but linearly in rural sites. The degrees of ozone sensitivity towards NOx or VOC emissions were correlated with base-case H2O2/HNO3 concentration ratio. This ratio appears to be a good indicator for regions that were sensitive to either NOx or VOC emissions changes, where a large ratio suggests a higher degree of ozone response to changes in precursor emissions.
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Details
- Title
- Aerosol and ozone sensitivity analysis with the community multi-scale air quality (CMAQ) model for the Pacific Northwest
- Creators
- Jack Chi-Mou Chen
- Contributors
- Brian K. Lamb (Degree Supervisor)
- Awarding Institution
- Washington State University
- Academic Unit
- Civil and Environmental Engineering, Department of
- Theses and Dissertations
- Master of Science (MS), Washington State University
- Publisher
- Washington State University; Pullman, Wash. :
- Identifiers
- 99900525298001842
- Language
- English
- Resource Type
- Thesis