Analysis of the Effects of Global Changes upon US Air Quality and North American Background Ozone
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This dissertation develops an analysis of changes in United States air quality in response to changes in climate and in global and local biogenic and anthropogenic emissions. Results from a global climate model driven with the A1B emission scenario from the IPCC were downscaled using a regional climate model. Downscaled meteorology was used to calculate current and future biogenic and wildfire emissions with MEGAN and the FSB-BlueSky framework, respectively. Current global emissions were estimated by POET and EDGAR emission inventories and adjusted to 2050 using the IPCC A1B emission scenario. Regional anthropogenic emissions were obtained from the EPA NEI 2002 emission inventory and projected to 2050 using the MARKAL model. Global emissions for black and organic carbon were obtained from Bond et al (2004). Air quality simulations using the Community Multi-scale Air Quality Model (CMAQv4.7) were developed for two nested domains with 220 km and 36 km horizontal grid cell resolution for a semi-hemispheric domain and a continental US domain. The simulation results suggest that O3 will increase between 2 to 12 ppb across the United States, with the highest increases in the South, Central and Midwest regions of the US. These increased levels occur due to increases in temperature, enhanced biogenic emissions and changes in land use and these increases are only partially offset by ozone reductions associated with reduced US emissions. Simulations show localized increases of PM2.5 between 2 and 4 μg/m3 in the Northeast, Southeast and South regions, mostly from enhanced biogenic emissions and changes in land use, while the Northwest and Central regions experienced reductions in PM2.5 due to future regional emissions reduction and increases in precipitation. Simulations show an increase in regional ozone up to 10 ppb and between 5 and 80 µg/m3 of PM2.5 as a result of current and future wildfires. Global change will have an overall negative effect upon North American background ozone which is projected to increase from 20 to 40 ppb in the current decade to 25 to 45 ppb in the future.