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Overview

Perspectives in Designing and Operating a Regional Ammonia Monitoring Network Gary Lear USEPA Clean Air Markets Division. Overview. Ammonia gas isn’t ordinary! Monitoring is expensive! How useful are traditional monitoring networks for measuring ammonia?. Overview. Not examining:

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Overview

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  1. Perspectives in Designing and Operating a Regional Ammonia Monitoring NetworkGary LearUSEPAClean Air Markets Division

  2. Overview • Ammonia gas isn’t ordinary! • Monitoring is expensive! • How useful are traditional monitoring networks for measuring ammonia?

  3. Overview • Not examining: • Organizational or infrastructure needs • Spatial design of campaign-style monitoring • Methodology (Mark Sutton) • Covariance of ammonium particulate concentrations (John Walker)

  4. Objectives of regional monitoring networks • Provide quantifiable estimates of regional concentrations or depositions • Interpolations performed using number of techniques • Concentrations may be used to estimate deposition using inferential models or some other technique • Identify and characterize extent of “hot spots”

  5. Objectives of regional monitoring networks • Identify and characterize conditions in sensitive areas • Estuaries and critical environments • Low buffer capacity soils • Chemically sensitive atmospheres • Particulate nurseries • Understanding atmospheric conditions at existing monitoring stations

  6. Optimize measurement methods • Known accuracy and precision • Identify acceptable risk of: • False negative: Area is identified as not being an area of concern when it is • False positive: Area is identified as being an area of concern when it is not • Reliable • Affordable! • Capital equipment • Labor

  7. Optimize monitoring locations • Minimize uncertainty as function of cost • Predictive variance over grid • Must have understanding of granularity in concentrations • Representative of regional conditions • Measurement locations are spatially correlated at scale of interpolation technique

  8. What density of measurements do we need? • Extremely high spatial variance • Concentrations can vary by factor of 100 on spatial scale of 1 km • Time to call in the modelers?

  9. REMSAD (Regulatory Modeling System for Aerosols and Deposition) • Three dimensional grid-based Eulerian air quality model. • Resample modeled output using monitoring locations from 4 different networks • Interpolated re-sampled data using IDW • Compared re-sampled interpolations to original output

  10. REMSAD 30km Output Interpolated to 10km Grids (2000) Wet NH4+ Dry (NH3+NH4+)

  11. NADP/NTN • ~250 mostly rural and isolated sites

  12. CASTNET • Rural dry deposition network with regional distribution of 84 sites • Rural 82 • Suburban 2 • Urban 0

  13. Speciation Trends Network • Established to characterize the annual and seasonal spatial patterns of aerosols and track the progress of control programs • Rural 7 • Suburban34 • Urban 30

  14. NAMS • The NAMS (1,092 stations) are a subset of the NAMS network with emphasis being given to urban and multi-source areas. In effect, they are key sites under SLAMS, with emphasis on areas of maximum concentrations and high population density. • Rural 158 • Suburban 468 • Urban 459 • Unknown 7

  15. Wet NH4+ REMSAD 2000 Actual NADP 1999-2001

  16. Wet NH4+ REMSAD 2000 Re-Sampled as NADP

  17. Wet NH4+ REMSAD 2000 Re-Sampled as NADP

  18. REMSAD 2000 Wet NH4+ Re-Sampled as CASTNET

  19. REMSAD 2000 Wet NH4+ Re-Sampled as CASTNET

  20. REMSAD 2000 Wet NH4+ Re-Sampled as STN

  21. REMSAD 2000 Wet NH4+ Re-Sampled as STN

  22. Histograms of Differences Between REMSAD and Re-Sampled Wet NH4+ NADP CASTNET Re-Sampled as STN NAMS STN

  23. REMSAD 2000 Dry (NH3+NH4+) Re-Sampled as NADP

  24. REMSAD 2000 Dry (NH3+NH4+) Re-Sampled as NADP

  25. REMSAD 2000 Dry (NH3+NH4+) Re-Sampled as CASTNET

  26. REMSAD 2000 Dry (NH3+NH4+) Re-Sampled as CASTNET

  27. REMSAD 2000 Dry (NH3+NH4+) Re-Sampled as STN

  28. REMSAD 2000 Dry (NH3+NH4+) Re-Sampled as STN

  29. REMSAD 2000 Dry (NH3+NH4+) Re-Sampled as NAMS

  30. REMSAD 2000 Dry (NH3+NH4+) Re-Sampled as NAMS

  31. Histograms of Differences Between REMSAD and Re-Sampled Dry (NH3+NH4+) NADP CASTNET NAMS STN

  32. Summary • Traditional monitoring networks do have a role, but… • are likely to miss areas of highest concentrations • may have a substantial bias in interpolations • Rural monitoring appear to have less bias than urban networks

  33. Future Plans at EPA’sOffice of Atmospheric Protection • Establish pilot high temporal-resolution sites • Denuders • Passive ammonia sampling • Gas Particle Ion Chromatograph? • Geostatistical inferential modeling • Use CMAQ to define spatial structure of pollutant concentrations

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