Regional Modeling Update and Issues

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Regional ModelingUpdate and Issues
Luis F. Woodhouse, Ph.D.

• May 6, 2003

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Emissions and Meteorology
Regional Modeling
Microscale Modeling
Integrated Results
Risk Assessment
Mapping and Visualization
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Outline

• Review of last meeting
• Regional modeling update
• Model evaluation
• Comparison with previous studies
• Integrating microscale and regional modeling
• Future analysis
• Future statewide modeling considerations

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Review of Last Meeting (September 12, 2002)

• Previous studies
• UAM and CAMx with Carbon Bond IV
• Select toxics
• Small domain
• Present study
• CALGRID and CMAQ with SAPRC99
• Over 30 toxics
• Large domain
• Note CAMx not used since its implementation
  mechanism software is not publicly available

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Toxics

• 1,3-butadiene
• Formaldehyde
• Acetaldehyde
• Acrolein
• Benzene
• Carbon tetrachloride
• Chloroform
• Dichloromethane
• 1,2-Dichloroethane
• o-Dichlorobenzene
• p-Dichlorobenzene
• Ethylene oxide
• Styrene

• Toluene
• Vinyl Chloride
• Xylenes
• Hexavalent Chromium
• Diesel PM10
• PM10 Arsenic
• PM10 Beryllium
• PM10 Cadmium
• PM10 Lead
• PM10 Manganese
• PM10 Mercury
• PM10 Nickel
• PM10 Zinc

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Ventura
San Bernardino
Los Angeles
Riverside
Orange
San Diego
93,264 km2 87 x 67 grids (4 km x 4 km)
Mexico
Regional Modeling Domain
Regional Modeling Domain
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Model Inputs

• Emissions
• SCOS97 adjusted to 1998
• seasonal inventories (weekday/weekend)
• latest profiles, surrogates, and EMFAC2000 (with
  DTIM4)
• Meteorology
• CALMET diagnostic model using data from over 200
  sites
• MM5 prognostic model
• Boundary conditions
• same for each month, based on SCOS97

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Regional Modeling Update

• CALGRID
• January 1 to December 31, 1998
• CMAQ
• January, April, August and November 1998

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Model Performance

• Verify models ability to reproduce measured
  concentrations
• Ozone Performance standards are well established
• Toxics No established performance standards

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Model PerformanceConclusions

• Iterative process is needed to improve ozone
  performance
• In general, model predicted annual average toxics
  concentrations are comparable with observations
  for most species
• Results comparable with previous studies

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Ozone Model Evaluation

• Compared daily ratios of model-predicted to
  measured maximum ozone concentrations
• CALGRID closer to observations
• CMAQ over predicts

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Ozone Model Evaluation (cont.)

• Calculated daily average gross errors
• Measure models overall ability to reproduce
  observed hourly ozone at each site above a
  specified threshold concentration
• Iterative process

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Toxic VOCs Model Evaluation

• Annual average concentrations
• In general, model predictions are comparable with
  the measured annual concentrations for most
  toxics VOC species
• Some species are significantly under predicted by
  both models carbon
  tetrachloride, chloroform, ethylene chloride,
  styrene

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Annual Averages of Toxic VOCs
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Annual Averages of Toxic VOCs
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Annual Averages ofInert Toxics

• Diesel PM10
• Model predictions are comparable to observed
  elemental carbon results
• Hexavalent Chromium
• Model predictions are below detection limit
• PM10 components
• Performance depends on species

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Annual Average of Inert Toxics

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DIES in ug/m3 compared to elemental carbon
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Annual Average of Inert Toxics



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DIES in ug/m3 compared to elemental carbon
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CALGRID (1998)
Diesel PM10
Benzene
ppb
µg/m3
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Comparison withPrevious Studies

• MATES II
• April 1998 to March 1999 field study
• Models
• UAM and recently CAMx
• Carbon Bond IV reaction mechanism
• Our results are comparable

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Comparison with MATES IIBenzene
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Comparison with MATES II Diesel PM10 vs.
Elemental Carbon
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Comparison with MATES II Formaldehyde
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Integrating Microscale and Regional Modeling
Results

• Microscale modeling estimates near source impacts
  (meters)
• Regional modeling estimates impacts from sources
  in a large area (km)
• Issue
• double-counting

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Barrio Logan Modeling Results
DIESEL PM10
ISCST3 CALINE CALGRID
BARRIO CHULA EL
-----------BARRIO LOGAN-------------- LOGAN
VISTA CAJON
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Barrio Logan Modeling Results (cont.)
BENZENE
ISCST3 CALINE CALGRID
BARRIO CHULA EL
-----------BARRIO LOGAN-------------- LOGAN
VISTA CAJON
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Barrio Logan Modeling Results (cont.)
HEXAVALENT CHROMIUM
NA
ISCST3 CALINE CALGRID
BARRIO CHULA EL
---------BARRIO LOGAN-------------- LOGAN
VISTA CAJON
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Sensitivity Simulations Double Counting

• In Barrio Logan, local emissions contribute less
  than 1 of the annual average concentration of
  most toxic species.
• In Wilmington, local emissions contribute
  15-90 of the annual average concentrations
• Benzene (47)
• Diesel exhaust (40)
• 1,3-butadiene (16)

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simulations for all 1998 were done in each case
with CALGRID
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Sensitivity SimulationsBarrio Logan

• Changing boundary conditions has very small
  impact on annual average toxic concentrations
• Choosing different averaging periods
• 12-month average toxic concentrations can be
  significantly different from 4-month average
  concentrations
• 4-month average cumulative risk is about 10
  higher than the 12-month average cumulative risk

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Future Analysis

• Improve estimates of background toxic
  concentrations
• Omit all toxics emissions in a cell
• Omit toxic emissions from selected categories in
  a cell
• Evaluate procedures for estimating contributions
  of secondary species
• Evaluate deposition effect
• Run CALGRID using MM5 winds
• Conduct spatial analysis

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Future Statewide Modeling Considerations

• Air quality model selection
• CALGRID, CMAQ, CAMx, other
• Atmospheric reaction mechanism
• Run time (e.g., CALGRID with SAPRC99 and 4 km x 4
  km grids, at least 6 months)
• Period simulated
• Every day in a year or selected episodes

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Future Statewide Modeling Considerations (cont.)

• Input preparation
• Emissions
• Meteorology (CALMET, MM5)
• Other considerations
• Baseline year
• Multiple year simulation
• Storage requirements

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