Background Air Quality in the United States Under Current and Future Emissions Scenarios Zachariah Adelman, Meridith Fry, J. Jason West Department of Environmental Sciences and Engineering University of North Carolina Pat Dolwick, Carey Jang Office of Air Quality Planning and Standards United States Environmental Protection Agency Presented at the 10 th Annual CMAS Conference October 24-26, 2011 Chapel Hill, NC
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Background Air Quality in the United States Under Current and Future Emissions Scenarios Zachariah Adelman, Meridith Fry, J. Jason West Department of Environmental.
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Background Air Quality in the United States Under Current and Future Emissions Scenarios
Zachariah Adelman, Meridith Fry, J. Jason WestDepartment of Environmental Sciences and EngineeringUniversity of North Carolina
Pat Dolwick, Carey JangOffice of Air Quality Planning and StandardsUnited States Environmental Protection Agency
Presented at the 10th Annual CMAS ConferenceOctober 24-26, 2011 Chapel Hill, NC
10th Annual CMAS Conference 1 Chapel Hill, NC
Motivation and Objectives• Will U.S. background air pollutant concentrations
increase in the future?• Objectives:
– Gather and process latest IPCC inventories for current and future year emissions estimates
– Use MOZART-4 to simulate future air quality resulting from climate change mitigation emissions scenarios
– Estimate background air quality in the U.S. by “zeroing-out” North American anthropogenic emissions
– Downscale global modeling results to produce boundary conditions for regional modeling
Methods and Data• Chemistry-Transport Model: MOZART-4• Meteorology: 2005 GEOS-5 1.9°x2.5°• Emissions Inventory: 2005 and 2030 Representative
Concentration Pathways (RCP)– RCP8.5 – Business as usual emissions– RCP4.5 – Best estimate emissions reduction– RCP2.6 – Maximum emissions reduction
• Zero-out North America (ZONA): – U.S., Canada, Mexico anthropogenic emissions set to zero
• Includes near-shore (< 50km) shipping, aircraft < 3km, and fertilizer
10th Annual CMAS Conference 2 Chapel Hill, NC
Methods and Data• Emissions processing with
custom IDL and NCL scripts– Speciate with RCP to
MOZART-4 conversion factors– Temporalize with RETRO
monthly profiles– Regrid to GEOS-5 grid– Merge natural and
anthropogenic sectors and create MOZART-ready files
1. These results indicate that only the emissions scenario that pursued extremely aggressive climate change mitigation (RCP2.6) lead to reductions in global O3 burden and U.S. background O3 and PM2.5 concentrations.
2. Annual maximum U.S. 8-hr O3 concentrations and frequency of high (> 70 ppb) 8-hr O3 events are predicted to decrease in all simulated future emissions cases, likely due to domestic emission controls
3. Contribution of background to total U.S. O3 concentrations predicted to increase in the future (~2-5% to annual mean and up to 10% to summer mean): combination of rise in transported O3 and drop in domestic O3 production
Future Work
• Probe MOZART process-level output to gain a better understanding of the differences between the RCP results
• Run CMAQ with the downscaled 2005 and 2030 BCs and recalculate U.S. background concentrations