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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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Statewide protocol regional application l.jpg

California Environmental Protection Agency

Air Resources Board

Statewide Protocol:Regional Application

Luis F. Woodhouse

August 27, 2003


Slide2 l.jpg

CHAPIS

Modeling Framework

Emissions and

Meteorology

Microscale

Modeling

Regional

Modeling

Integrated

Results

HARP

Risk

Assessment

Mapping and

Visualization

2


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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


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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


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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


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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

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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


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Ideal case

Uses large modeling domain that includes entire state

Resource intensive and requires long run time

Modeling Domain

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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


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Air Quality Models Selection

  • Sound scientific basis

  • Reflect up-to-date-science

  • Documentation

  • Source code and technical documentation available to the public

10


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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

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Chemical Reaction MechanismSelection

  • Successful peer review

  • Extensively tested

  • Represents recent advances in science

  • Publicly available

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Chemical Reaction Mechanism (cont.)

For statewide annual simulations:

  • Selected SAPRC99 reaction mechanism

  • Added explicit reactions for selected toxics

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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

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Meteorological Model Selection

  • Peer review process

  • Fully documented

  • Reflects recent advances in science

  • Publicly available

15


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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


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Meteorological Models (Cont.)

  • Evaluation of input and output data from meteorological models:

    • Overall pattern for selected periods

    • Predictions vs. observations for selected periods

17


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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


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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

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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)

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Summary

  • Developed criteria for:

    • model selection

    • input preparation

    • input evaluation

    • model output evaluation

  • Optimization of statewide modeling

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