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 b Models-3/CMAQ system One-Atmosphere perspectiveOne-Atmosphere perspective b Multi-Scale Applications of Models-3/CMAQ Western U.S. ApplicationWestern U.S. Application Annual Nationwide U.S. ApplicationAnnual Nationwide U.S. Application Eastern U.S. ApplicationEastern U.S. Application Hemispheric/Continental Modeling InitiativeHemispheric/Continental Modeling Initiative

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

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

Acid Rain (NO 3 - deposition) Water Quality (Nitrogen deposition, Lake Acidification) NO x Visibility (Fine PM) (NOx + VOC + hv) --> Ozone (NO 3 -, NH 4 + ) PM NO x -Related Air Quality Issues

Acid Rain ( SO 4 2- deposition) SO x (Fine PM) Visibility (SO 4 2-, NH 4 + ) PM SO x -Related Air Quality Issues Water Quality (Lake acidification, Toxics deposition)

Air Toxics Ozone Acid Rain Visibility PM 2.5 WaterQuality. OH. OH role in pollutants formation : One-Atmosphere NOx + VOC + OH + hv ---> O 3 SOx [or NOx] + NH 3 + OH ---> (NH 4 ) 2 SO 4 [or NH 4 NO 3 ] SO 2 + OH ---> H 2 SO 4 NO 2 + OH ---> HNO 3 VOC + OH ---> Orgainic PM OH Air Toxics (POPs, Hg (II), etc.) Fine PM (Nitrate, Sulfate, Organic PM) NOx + SOx + OH (Lake Acidification, Eutrophication)

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

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

Impact of 50% NOx emission reduction O 3 decrease HOx decrease

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

Western U.S. Application b Objectives : New M3/CMAQ Domain New Episode (July 1996) b Model Setup : Episodic O 3 modeling Meteorology : MM5 Emissions : Tier-2 regridded 36km/12km, 12 layers Compare against observations and UAM-V

Annual Nationwide U.S. Application b Objectives : Annual CMAQ Run Nationwide CMAQ Domain b Model Setup : Annual PM and O 3 (1996) 36-km, 8 vertical layers Meteorology : MM5 Emissions Processing: SMOKE Model Evaluation: Compared against observed data (IMPROVE & CASTNET) & REMSAD

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

National 1996 CMAQ Modeling: O 3 (July Max) Visibility (1996 avg.)

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

CMAQ Sensitivity Studies b CB4 vs. RADM2 Is RADM2 a better mechanism than CB4 for PM modeling?Is RADM2 a better mechanism than CB4 for PM modeling? Run CMAQ w/ both CB4 and RADM2 for January and July, 1996Run CMAQ w/ both CB4 and RADM2 for January and July, 1996 b NH 3 sensitivity Are NH 3 emissions the culprit of nitrate PM over- prediction?Are NH 3 emissions the culprit of nitrate PM over- prediction? Run CMAQ w/ 50% reduction of NH 3 emissions for January and July, 1996Run CMAQ w/ 50% reduction of NH 3 emissions for January and July, 1996 b Boundary conditions sensitivity Run CMAQ w/ 10 ppb O3 increase along the western boundary for January and July, 1996Run CMAQ w/ 10 ppb O3 increase along the western boundary for January and July, 1996

PM 2.5 (January Avg.) RADM2 Original CB4

PM_SO 4 (Jan. Avg.) Orig. CB4 RADM2 Fixed CB4

NH 3 Sensitivity Modeling Nitrate PM : (January Avg.) Base 50% NH 3 reduction Base 50% NH 3 reduction

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

Eastern U.S. Application b Objectives : SIP and urban applications Emission growth & control Nested MM5 runs b Features : O 3 and PM, July 95 OTAG-like 36/12-km domain, nested with 4-km (NE, LM, AT, TX) SMOKE : Emissions processing

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

Background : b O 3 and PM are not only key air pollutants, but also major climate- forcing substances; b Reduction of non-CO 2 substances (e.g., O 3 and PM, especially black carbon) could be a viable alternative to CO 2 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); b Black carbon could be the second largest heating component after CO 2 contributing to global warming; Control of fossil-fuel black carbon could be the most effective method of slowing glabal warming (Jacobson, Nature, 2001); Climate Change/Air Pollution Modeling Initiative

(Hansen et al., PNAS2001) Climate Change/Air Pollution Modeling Initiative O 3 ( ) Black (0.8) Carbon

Background (continued): b 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. b For example, recent modeling studies showed that by 2020 Asian emissions could contribute as much as 2 ~ 6 ppb of O 3 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 O 3 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, –! Climate Change/Air Pollution Modeling Initiative

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

Objectives : b 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. b To explore the impacts of intercontinental transport of O 3 and PM as well as their implications for domestic and regional air quality and global climate change b To design integrated emissions control strategies to benefit global climate and regional and local air quality simultaneously Climate Change/Air Pollution Modeling Initiative

Work Plan : Phase I : Short-Term (~6 months) b 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 b Develop a conceptual model and modeling protocol under the guidance of an expert advisory panel 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 Climate Change/Air Pollution Modeling Initiative

Thank you The End