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Carey Jang, Pat Dolwick, Norm Possiel, Brian Timin, Joe Tikvart U.S. EPA

Multi-Scale Applications of U.S. EPA’s Third-Generation Air Quality Modeling System (Models-3/CMAQ). Carey Jang, Pat Dolwick, Norm Possiel, Brian Timin, Joe Tikvart U.S. EPA Office of Air Quality Planning and Standards (OAQPS) Research Triangle Park, NC , U.S.A. OUTLINE.

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Carey Jang, Pat Dolwick, Norm Possiel, Brian Timin, Joe Tikvart U.S. EPA

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  1. Multi-Scale Applications of U.S. EPA’s Third-Generation Air Quality Modeling System (Models-3/CMAQ) Carey Jang, Pat Dolwick, Norm Possiel, Brian Timin, Joe Tikvart U.S. EPA Office of Air Quality Planning and Standards (OAQPS) Research Triangle Park, NC , U.S.A.

  2. OUTLINE • Models-3/CMAQ system • One-Atmosphere perspective • Multi-Scale Applications of Models-3/CMAQ • Western U.S. Application • Annual Nationwide U.S. Application • Eastern U.S. Application • Hemispheric/Continental Modeling Initiative

  3. Features of Models-3/CMAQ • “Open-Access” Community-Based Models : • User-friendly, Modular, Common modeling framework for scientists and policy-makers. • Advanced Computer Technologies : • High performance hardware and software technologies (Cross-platform, GUI, distributed computing, visualization tools, etc.). • “One-Atmosphere” Modeling : • Multi-pollutant (Ozone, PM, visibility, acid deposition, air toxics, etc.), Multi-scale.

  4. Regulating Air Pollution: One-Atmosphere Approach Mobile Sources Ozone NOx, VOC, Toxics PM (Cars, trucks, airplanes, boats, etc.) Industrial Sources Acid Rain Chemistry Meteorology Visibility NOx, VOC, SOx, Toxics (Power plants, factories, refineries/chemical plants, etc.) Air Toxics Area Sources Atmospheric Deposition NOx, VOC, Toxics (Homes, small business, farming equipment, etc.)

  5. NOx-Related Air Quality Issues (NO3-, NH4+) PM (NOx + VOC + hv) --> Ozone NOx Acid Rain (NO3- deposition) Visibility (Fine PM) Water Quality (Nitrogen deposition, Lake Acidification)

  6. SOx-Related Air Quality Issues (Fine PM) Visibility (SO42-, NH4+) PM SOx Acid Rain (SO42-deposition) Water Quality (Lake acidification, Toxics deposition)

  7. .OH role in pollutants formation : One-Atmosphere PM2.5 SOx [or NOx] + NH3 + OH ---> (NH4)2SO4 [or NH4NO3] VOC + OH ---> Orgainic PM One Atmosphere Ozone Visibility One Atmosphere Fine PM (Nitrate, Sulfate, Organic PM) .OH NOx + VOC + OH + hv ---> O3 Acid Rain Water Quality SO2 + OH ---> H2SO4 NOx + SOx + OH (Lake Acidification, Eutrophication) NO2 + OH ---> HNO3 OH <---> Air Toxics (POPs, Hg(II), etc.) Air Toxics

  8. Example of “One-Atmosphere” Modeling Impact of 50 % NOx Emission Reduction on PM 2.5

  9. Impact of 50% NOx emission reduction Nitrate PM decrease Sulfate PM decrease

  10. Impact of 50% NOx emission reduction O3 decrease HOx decrease

  11. Models-3/CMAQ Applications at OAQPS Purpose:To evaluate Models-3/CMAQ feasibility as a regulatory tool • Western U.S. Application • New domain, episodic O3 • Annual Nationwide U.S. Application • Annual PM & visibility • Eastern U.S. Application • Urban & SIP applications • Hemispheric/continental Modeling Initiative • Linkage of climate change and air pollution

  12. Western U.S. Application • Objectives : • New M3/CMAQ Domain • New Episode (July 1996) • Model Setup : • Episodic O3 modeling • Meteorology : MM5 • Emissions : Tier-2 regridded • 36km/12km, 12 layers • Compare against observations and UAM-V 177 153

  13. Annual Nationwide U.S. Application • Objectives : • Annual CMAQ Run • Nationwide CMAQ Domain • Model Setup : • Annual PM and O3 (1996) • 36-km, 8 vertical layers • Meteorology : MM5 • Emissions Processing: SMOKE • Model Evaluation: Compared against observed data (IMPROVE & CASTNET) & REMSAD

  14. Models-3/CMAQ Simulation: Annual Average PM 2.5 Sulfate PM Organic PM Nitrate PM

  15. National 1996 CMAQ Modeling: Visibility (1996 avg.) O3 (July Max)

  16. National 1996 CMAQ Modeling (January average) Nitrogen Wet Deposition Sulfur Wet Deposition

  17. CMAQ Sensitivity Studies • CB4 vs. RADM2 • Is RADM2 a better mechanism than CB4 for PM modeling? • Run CMAQ w/ both CB4 and RADM2 for January and July, 1996 • NH3 sensitivity • Are NH3 emissions the culprit of nitrate PM over-prediction? • Run CMAQ w/ 50% reduction of NH3 emissions for January and July, 1996 • Boundary conditions sensitivity • Run CMAQ w/ 10 ppb O3 increase along the western boundary for January and July, 1996

  18. PM 2.5 (January Avg.) Original CB4 RADM2

  19. PM_SO4 (Jan. Avg.) Orig. CB4 RADM2 Fixed CB4

  20. NH3 Sensitivity Modeling Nitrate PM : (January Avg.) Base 50% NH3 reduction

  21. CMAQ Sensitivity : Boundary Conditions Effect of a 10 ppb ozone increase along the western boundary

  22. Eastern U.S. Application • Objectives : • SIP and urban applications • Emission growth & control • Nested MM5 runs • Features : • O3 and PM, July 95 • OTAG-like 36/12-km domain, nested with 4-km (NE, LM, AT, TX) • SMOKE : Emissions processing

  23. Climate Change/Air Pollution Modeling Initiative Proposal : • Global and Regional Modeling of Ozone and PM Goal : • Establish linkages between climate change and air pollution

  24. Climate Change/Air Pollution Modeling Initiative Background : • O3 and PM are not only key air pollutants, but also major climate-forcing substances; • Reduction of non-CO2 substances (e.g., O3 and PM, especially black carbon) could be a viable alternative to CO2 reduction to curb global warming. A key strategy suggested was to focus on air pollution to benefit regional and local air quality and global climate simultaneously (Hansen et al., PNAS, 2000); • Black carbon could be the second largest heating component after CO2 contributing to global warming; Control of fossil-fuel black carbon could be the most effective method of slowing glabal warming (Jacobson, Nature, 2001);

  25. Climate Change/Air Pollution Modeling Initiative O3 (0.3+0.1) Black (0.8) Carbon (Hansen et al., PNAS2001)

  26. Climate Change/Air Pollution Modeling Initiative Background (continued): • There is also mounting evidence that criteria pollutants originating from some developing countries, especially those in Asia such as China and India, could impact U.S. domestic air quality as well as contribute to the global background of climate-forcing substances. This intercontinental transport issue is expected to worsen with the rapid growth in emissions in these regions. • For example, recent modeling studies showed that by 2020 Asian emissions could contribute as much as 2 ~ 6 ppb of O3 in the western U.S., offsetting the Clean Air Act efforts up to 25% in that region (Jacob et al., Geophys. Res. Letts., 1999) and increase global mean O3 level up to 10% (Collins et al., Atmos. Env., 2000); Asian and Sahara dust could contribute a significant amount of PM in the western and southeastern U.S. (Husar, http://capita.wustl.edu/CAPITA/). • !

  27. Climate Change/Air Pollution Modeling Initiative (Byun and Uno, 2000)

  28. Climate Change/Air Pollution Modeling Initiative Objectives : • To evaluate available approaches for establishing the linkages between air pollution and climate change and enhancing modeling capacity within EPA to address these linkage issues. • To explore the impacts of intercontinental transport of O3 and PM as well as their implications for domestic and regional air quality and global climate change • To design integrated emissions control strategies to benefit global climate and regional and local air quality simultaneously

  29. Climate Change/Air Pollution Modeling Initiative Work Plan : Phase I : Short-Term (~6 months) • Establish a better scientific foundation in linking climate change and air pollution by leveraging current studies 1. Global Modeling of O3 and PM 2. Global Radiative Forcing of Aerosols 3. Emission Inventories for Climate-Forcing Pollutants • Develop a conceptual model and modeling protocol under the guidance of an expert advisory panel

  30. Climate Change/Air Pollution Modeling Initiative Work Plan : Phase II : Long-Term (1 ½~2 years) Based on Phase I effort, a series of modeling efforts that will be conducted to address the linkages between air pollution and climate change. These efforts may include: – Enhancement of modeling capability and emission inventories to better represent the linkages to global air quality and climate. – Development of nesting capability between global chemistry/climate models and regional air quality models. – Simulation of hemispheric or regional air quality under a variety of scenarios about future global and regional emissions and air quality. – Evaluation of global and regional air quality models using a diverse set of observational data sets, including data from satellites, surface networks, intensive field studies, etc. – Assessment of the potential radiative forcing and climate benefits resulting from planned and alternative non-CO2 control strategies

  31. The End Thank you

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