Modeling Compliance with the 8-Hour Standard

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Modeling Compliance with the 8-Hour Standard

• Jay Olaguer
• Houston Advanced Research Center
• 10/06/04

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Texas Environmental Research Consortium

• TERC is a consortium of stakeholders
• Local government agencies (City of Houston, HGB
  and DFW counties)
• Environmentalists (ED, GHASP)
• Business and Industry (GHP, Dallas C of C).
• TERCs mission
• Fund research to improve ozone science and air
  modeling in East Texas
• 5 million from TX Legislature for 2004-2005
• Collaboration with TCEQ in identifying research

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Basic Problem

• How to model attainment of 8-hr standard?
• Transport yields background up to 80 ppb
• Current AQ models used for SIPs are barely
  sufficient for 1-hr, let alone 8-hr
• Selection of appropriate episode(s) not
  straightforward (Full ozone season?)
• Need much more observational data to evaluate
  model performance

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Meteorology

• 1-hr Standard 8-hr Standard
• Boundary Layer Free Troposphere
• (0-3 km) (3-16 km)
• Horizontal Flow Vertical Motion

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Transport

• 1-hr Standard 8-hr Standard
• Daytime Night-time
• Urban-to-Regional Regional-to-Continental

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Chemistry

• 1-hr Standard 8-hr Standard
• Highly Reactive Moderately Reactive
• VOCs (e.g., ethylene) VOCs (e.g.,
  n-butane)
• Rapid Ozone Long-Lived Products
• Formation (e.g., PAN, acetone)

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8-Hr Conceptual Model

• Explain high background ozone in E. TX
• Explain local 8-hour exceedances in HGBPA, DFW,
  NE TX EAC areas.
• Information sources surface monitors, previous
  conceptual models, trajectory analyses, forecast
  modeling (NCAR)
• Statistical and physical model analysis to get a
  mental picture of causal mechanism

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Transport from Out-of-State

• Examine transport impact of out-of-state sources
  on E. Texas regions
• Apportion source region/type contributions for
  various meteorological episodes
• Aug 1999 DFW episode
• Sep 1999 Austin/San Antonio episode
• Aug/Sep 2000 HGB episode
• Sensitivity to height of air column in model

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Best Practice for Modeling 8-Hr Ozone in Context
of TexAQS II

• Real-time trajectory and grid modeling for
  forecasting/adaptive observation planning
• Testing of modeling innovations
• Observational data assimilation
• Expanded chemical mechanism
• Source attribution methods
• Development of regional model for 8-hour SIP
  applications

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Summer 2005 Tetroon Campaign

• Constant altitude balloons to track air flow
• Tower and/or chase aircraft chemical measurements
  (ozone, VOCs, NOy)
• Research Focus
• Nocturnal meteorology and transport
• Nocturnal chemistry
• Export of pollution from Houston to E. Texas

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Summary

• Meteorology
• Conceptual model development
• Testing model innovations during TexAQS II
• Transport
• Regional modeling and source apportionment
• Tetroon campaign to track regional air flow
• Chemistry
• Chemical measurements on tower/aircraft
• Expanded model chemical mechanism