Implementation of the Particle

1
Implementation of the Particle Precursor
Tagging Methodology (PPTM) for the CMAQ Modeling
System Sulfur Nitrogen Tagging

• 5th Annual CMAS Conference
• Friday Center, UNC-Chapel Hill, NC
• 17 October 2006
• Tom Myers, Sharon Douglas Jay Haney
• ICF International, San Rafael, CA

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Presentation Outline

• Conceptual overview of PPTM
• Implementation of PPTM for sulfur and nitrogen in
  the CMAQ model
• Testing example results
• S tagging application for pulp paper sector

3
Overview of PPTM Concepts

• Emissions (or initial/boundary condition) species
  are tagged in the emissions (or IC/BC) files and
  continuously tracked throughout the simulation
• Tags can be applied to source regions, source
  categories, individual sources, initial
  conditions, and/or boundary conditions
• PPTM quantifies the contribution of tagged
  sources to simulated species concentrations
  deposition
• Base simulation results not affected by tagging

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Overview of PPTM Concepts

• Within the model, tagging is accomplished by the
  addition of duplicate species (e.g., SO2_t1,
  SO2_t2)
• Tagged species have the same properties and are
  subjected to the same processes (e.g., advection,
  chemical transformation, deposition) as the
  actual species
• Mercury (Hg), sulfur (S), and nitrogen (N)
  tagging completed tagging for elemental carbon
  (EC) and organic carbon (OC) under
  development/testing

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Example Uses of PPTM for Sulfur and Nitrogen

• Determine the contribution of SO2 emissions from
  an individual source, group of sources, or source
  category (e.g., electric generating units (EGUs),
  pulp and paper facilities) to sulfate and overall
  PM2.5 concentrations
• Quantify/compare the contribution of NOx
  emissions from transportation sources, area
  sources (e.g., wood burning stoves) offroad
  sources (e.g., IC engines, construction
  equipment) 

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Implementation of PPTM for CMAQ Sulfur Nitrogen

• CMAQ version 4.5
• Tagged S elements include
• SO2, ASO4I, ASO4J, SULF (for internal tracking)
• Tagged N species include
• ANH4I, ANH4J, ANO3I, ANO3J, NO, NO2, NO3, N2O5,
  HNO3, HONO, PNA, PAN, NTR, NH3

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Implementation of PPTM for CMAQ Sulfur Nitrogen

• Key considerations/assumptions
• Linear processes simulated directly
• Potentially non-linear processes calculated for
  total species and apportioned to tags
• Additional terms from some processes saved to
  ensure proper allocation
• Gas-phase chemistry routines have additional
  production loss terms added NO, NO2, NO3, N2O5
  changes apportioned based on NOx totals for each
  tag

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Implementation of PPTM for CMAQ Sulfur Nitrogen

• Key considerations/assumptions
• Other N species calculated with additional
  chemistry terms adjusted so net production/loss
  for sum of tags matches that for the whole
• Simulation calculates the overall species value
  as the sum of all tags tags must be defined to
  add up to the whole

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Implementation of PPTM for CMAQ Sulfur Nitrogen

• CPU requirements increased by approximately 15
  for 3 S tags and 50 for 3 N tags
• Documentation/users guide available from EPA or
  ICF as follows

Douglas, S., T. Myers and Y. Wei. 2006.
Implementation of Sulfur and Nitrogen Tagging in
the Community Multiscale Air Quality (CMAQ)
Model. Prepared for EPA, OAQPS, Research
Triangle Park, NC. ICF International, San
Rafael, California (06-076).
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Example Sulfur Tagging Results
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CMAQ PPTM Contribution to Monthly Average Sulfate

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CMAQ PPTM Contribution to Monthly Average Sulfate

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CMAQ PPTM Contribution to Monthly Average Sulfate

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CMAQ PPTM Site-specific SO4 Contributions
(IMPROVE Sites)

ugm-3
CMAQ simulated monthly average contribution to
sulfate from three example EGU facilities.
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Sulfur Tagging Application for the Pulp Paper
Sector

• Based on CAIR 2010 modeling emission inventory
• 1 month simulation period (July)
• (Annual simulation ongoing)
• Tags applied for 10 pulp paper sources and
  IC/BCs

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CMAQ PPTM Monthly Average Sulfate for July 2010

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CMAQ PPTM Contribution to Monthly Average Sulfate

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CMAQ PPTM Contribution to Monthly Average Sulfate

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CMAQ PPTM Site-specific SO4 Contributions
(IMPROVE Sites)

ugm-3
CMAQ simulated monthly average contribution to
sulfate from regional pulp paper facilities.
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CMAQ PPTM Site-specific SO4 Contributions (Urban
Sites)

ugm-3
CMAQ simulated monthly average contribution to
sulfate from regional pulp paper facilities.
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CMAQ PPTM Site-specific SO4 Contributions (Urban
Sites)

ugm-3
CMAQ simulated monthly average contribution to
sulfate from regional pulp paper facilities.
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Example Nitrogen Tagging Results
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Example CMAQ PPTM Nitrogen Tagging Results Great
Smoky Mtns
NH4
NOx
NO3
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Example CMAQ PPTM Nitrogen Tagging Results Great
Smoky Mtns
NOx
NH4
NO3
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Summary of CMAQ PPTM Status and Next Steps

• PPTM has been successfully implemented in the
  CMAQ model for S, N (and Hg) and quantifies the
  contribution of tagged sources to simulated PM
• Application interpretation of results is
  straightforward (no hidden assumptions)
• Initial test results indicate that numerical
  effects (uncertainties) are small, compared to
  contribution estimates
• Next steps include
• Complete implementation for OC EC
• Add OPTM (for ozone)