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Statewide Protocol: Regional Application

California Environmental Protection Agency. Air Resources Board. Statewide Protocol: Regional Application. Luis F. Woodhouse. August 27, 2003. CHAPIS. Modeling Framework. Emissions and Meteorology. Microscale Modeling. Regional Modeling. Integrated Results. HARP. Risk Assessment.

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Statewide Protocol: Regional Application

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  1. California Environmental Protection Agency Air Resources Board Statewide Protocol:Regional Application Luis F. Woodhouse August 27, 2003

  2. CHAPIS Modeling Framework Emissions and Meteorology Microscale Modeling Regional Modeling Integrated Results HARP Risk Assessment Mapping and Visualization 2

  3. Objectives • Simulate year 2000 air quality, including toxics, for all California using regional air quality models. • Will provide background concentrations to be used with local dispersion modeling. 3

  4. Previous Experience • Modeled southern California for year 1998 • Air quality models: CMAQ and CALGRID • Meteorological models: MM5 and CALMET • Developed annual model performance metrics (toxics and other species) • Conducted sensitivity tests to expedite simulation while minimizing error introduced 4

  5. Challenges for Statewide Modeling • Very large modeling domain • Potentially long run time (meteorological and regional models) • Storage and processing of very large input and output files • Evaluation of models input/output data • Apply lessons learned to optimize statewide modeling • Double counting 5

  6. Optimizing Statewide Regional Modeling • Apply lessons learned from previous experience modeling southern California • Shorter time periods to represent year • Use of subdomains to cover entire State • Leveraging from other studies: • SCOS/CCOS/CRPAQS modeling and databases 6

  7. Statewide Protocol:Regional Modeling • Establishes criteria for conducting air quality modeling for toxic air pollutants: • Modeling domain definition • Selection and evaluation of models • Selection of chemical mechanism • Preparation of annual emissions inventory • Initial and boundary conditions • Evaluation of models results 7

  8. Ideal case Uses large modeling domain that includes entire state Resource intensive and requires long run time Modeling Domain 8

  9. For statewide simulation: Use 4 subdomains to cover state (4-km x 4-km grid) Each subdomain modeled independently Less resource intensive and faster run times for each subdomain SCOS subdomain by early 2004 Modeling Domain (cont.) 9

  10. Air Quality Models Selection • Sound scientific basis • Reflect up-to-date-science • Documentation • Source code and technical documentation available to the public 10

  11. Air Quality Models (cont.) For statewide simulation: • State-of-the-science models will be evaluated (such as Models-3/CMAQ, CAMx and CALGRID) • Criteria defined in protocol to evaluate model performance for ozone and toxics 11

  12. Chemical Reaction MechanismSelection • Successful peer review • Extensively tested • Represents recent advances in science • Publicly available 12

  13. Chemical Reaction Mechanism (cont.) For statewide annual simulations: • Selected SAPRC99 reaction mechanism • Added explicit reactions for selected toxics 13

  14. 1,3-butadiene Formaldehyde Acetaldehyde Acrolein Benzene Carbon tetrachloride Chloroform Dichloromethane 1,2-Dichloroethane o-Dichlorobenzene p-Dichlorobenzene Ethylene oxide Perchloroethylene Styrene Toluene Trichloroethylene Vinyl Chloride Xylenes Diesel PM10 Other PM10 species: Arsenic, Beryllium, Cadmium, Hexavalent Chromium, Iron, Lead, Manganese, Mercury, Nickel, Zinc and elemental carbon Toxics 14

  15. Meteorological Model Selection • Peer review process • Fully documented • Reflects recent advances in science • Publicly available 15

  16. Meteorology Models (cont.) • For statewide modeling two meteorological models will be applied: • MM5: A prognostic model that predicts from first principles, mass and energy transfer equations • CALMET: A diagnostic model that uses observational data 16

  17. Meteorological Models (Cont.) • Evaluation of input and output data from meteorological models: • Overall pattern for selected periods • Predictions vs. observations for selected periods 17

  18. Emissions • Point and areawide emissions • Extrapolated from 1999 baseline • Use surrogates to allocate area sources to individual grids • On-road motor vehicle emissions • Latest versions of EMFAC and DTIM4 • require hourly temperature and relative humidity • Biogenic emissions • Weekday and weekend emissions by month 18

  19. Emissions (cont.) • Emissions will be evaluated before use in air quality models • Spatial pattern of emissions • Temporal patterns • Comparison of predicted and observed ratios of HC/NOx and CO/NOx 19

  20. Initial and Boundary Conditions • Protocol suggests default initial and constant boundary conditions • Boundary conditions same as for SCOS-97 • Pristine over ocean (40 ppb O3, 0.001 ppb NOx, and 20 ppbC VOC) • South Coast clean over land (40 ppb O3, 2 ppb NOx, 60 ppbC VOC) 20

  21. Summary • Developed criteria for: • model selection • input preparation • input evaluation • model output evaluation • Optimization of statewide modeling 21

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