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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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Presentation Transcript
slide2

CHAPIS

Modeling Framework

Emissions and

Meteorology

Microscale

Modeling

Regional

Modeling

Integrated

Results

HARP

Risk

Assessment

Mapping and

Visualization

2

objectives
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

previous experience
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

challenges for statewide modeling
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

optimizing statewide regional modeling
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

statewide protocol regional modeling
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

modeling domain
Ideal case

Uses large modeling domain that includes entire state

Resource intensive and requires long run time

Modeling Domain

8

modeling domain cont
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

air quality models selection
Air Quality Models Selection
  • Sound scientific basis
  • Reflect up-to-date-science
  • Documentation
  • Source code and technical documentation available to the public

10

air quality models cont
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

chemical reaction mechanism selection
Chemical Reaction MechanismSelection
  • Successful peer review
  • Extensively tested
  • Represents recent advances in science
  • Publicly available

12

chemical reaction mechanism cont
Chemical Reaction Mechanism (cont.)

For statewide annual simulations:

  • Selected SAPRC99 reaction mechanism
  • Added explicit reactions for selected toxics

13

toxics
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

meteorological model selection
Meteorological Model Selection
  • Peer review process
  • Fully documented
  • Reflects recent advances in science
  • Publicly available

15

meteorology models cont
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

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

17

emissions
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

emissions cont
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

slide20

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

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

21

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