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Causes of Haze Assessment

Causes of Haze Assessment. Mark Green Desert Research Institute Marc Pitchford, Chair Ambient Monitoring & Reporting Forum. Causes of Haze Assessment Goals & Objectives. Assess causes of haze for all WRAP Federal Class I Areas on a periodic basis – every five years

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Causes of Haze Assessment

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  1. Causes of Haze Assessment Mark Green Desert Research Institute Marc Pitchford, Chair Ambient Monitoring & Reporting Forum

  2. Causes of Haze Assessment Goals & Objectives • Assess causes of haze for all WRAP Federal Class I Areas on a periodic basis – every five years • Encourage broad-based stakeholder participation throughout the assessment process • Enhance the utility and accessibility of the results for • SIP & TIP development, • Regional air quality model evaluation & interpretation, • Identification of monitoring gaps, • Improved methodology for setting natural haze levels, & • Tracking effectiveness of emission control programs

  3. Causes of Haze AssessmentApproach • Data analysis methods are selected to respond to a series of questions concerning the causes of haze • Will require numerous methods applied to ambient monitoring data, but not regional air quality models • As they become available, AMRF reviews draft responses to each question & posts final responses to a web site • Results are designed for computer searches, with internal links and directories for an easily navigated virtual report

  4. WRAP/AMRF Causes of Haze Questions Each Analysis Method Addresses 1 or More of the Questions Contractor Data Analyses Separate Review & Posting for Each Analysis & Question WRAP/AMRF Review Draft Results WRAP/AMRF Post Final Results on Web Causes of Haze Assessment Process

  5. Each Question is Addressed at Each Class I Areas

  6. Each Analysis Method Addresses One or More Questions

  7. Causes of Haze AssessmentQuestions • What aerosol components are responsible for haze? • What are the major components for best, worst & average days & how do they compare? • How variable are they episodically, seasonally, interannually? • What site characteristics best group sites with similar patterns of major components? • How do the relative concentration of the major components compare with the relative emission rates nearby & regionally?

  8. Causes of Haze AssessmentQuestions - continued • What is meteorology’s role in the causes of haze? • How do meteorological conditions differ for best, worst and typical haze conditions? • What empirical relationships are their between meteorological conditions and haziness? • How well can haze conditions be predicted solely using meteorological factors? • What site characteristics best group sites with similar relationships between meteorological conditions and haze? • How well can interannual variations in haze be accounted for by variations in meteorological conditions?

  9. Causes of Haze AssessmentQuestions - continued • What are the emission sources responsible for haze? • What geographic areas are associated with transported air that arrives at sites on best, typical & worst haze days? • Are the emission characteristics of the transport areas consistent with the aerosol components responsible for haze? • What do the aerosol characteristics on best, typical and worst days indicate about the sources? • What does the spatial & temporal pattern analysis indicate about the locations and time periods associated with sources responsible for haze?

  10. Causes of Haze AssessmentQuestions - continued • What are the emission sources responsible for haze? - continued - • What evidence is there for urban impacts on haze & what is the magnitude & frequency when evident? • What connections can be made between sample periods with unusual species concentrations & activity of highly sporadic sources (e.g. major fires & dust storms)? • What can be inferred about impacts from sources in other states, other RPOs & other countries? • What refinements to default natural haze levels can be made using ambient monitoring and emission data?

  11. Causes of Haze AssessmentQuestions - continued • Are there detectable &/or statistically significant multi-year trends in the causes of haze? • Are the aerosol components responsible for haze changing? • Where changes are seen, are they the result of meteorological or emissions changes? • Where emissions are known to have changed, are there corresponding changes in haze levels?

  12. Assessment Approach • Start with basics, sequentially increase complexity • Most effort for 35 sites with 7 or more years data • Reduced set of analyses for remaining 44 sites with <3 years of data • Descriptive analyses, trajectory analyses, episode analysis, cluster analysis, factor analysis, receptor modeling, statistical tests

  13. Period of record for IMPROVE /protocol sites in WRAP region • 119 of 156 visibility protected Class I areas in WRAP region • 78 have IMPROVE sampler in or nearby Class I area • 3 Class I areas (Brand Canyon, Saguaro, and Yellowstone) have 2 IMPROVE monitoring sites • 37 of sites with relatively long-term data, starting between 1988 and 1994 • 28 sites >10 years data, 9 sites 7-9 years data • Remaining sites started between 1999 and 2002 ,0-3 years data

  14. Prepare emissions density maps • Help in interpreting the aerosol component data; • Determine relationship of sources to the Class I areas; • Interpreting results of backtrajectory analysis; • To examine relationships between mesoscale meteorological transport and efforts of the sources upon Class I areas

  15. Describe monitoring sites • Their representation of the Class I area and nearby Class I areas; • Relationship to terrain features, bodies of water, etc.; • Proximity to major point sources, cities, etc. Information from the emissions compilation described above will be quite useful.

  16. Assess meteorological setting of sites • Expected mesoscale flow patterns of interest (sea/land breeze, mountain/valley winds, convergence zones,etc.); • Orographic precipitation patterns (i.e. favored for precipitation, or in rain-shadow); • Inversion layers; • Potential for transport from cities and other significant sources/source areas.

  17. Aerosol data analysis • Descriptive statistics and interpretation for aerosol data- individual components and reconstructed extinction • Document, interpret component spatial and seasonal patterns- Best 20%, middle 60%, worst 20% reconstructed extinction days and seasonal patterns by site • Compile, describe spatial and seasonal patterns of aerosol components frequency distributions. • Interpret aerosol component data in light of emissions sources, monitoring site settings, backtrajectories • Cluster analysis to group sites with similar patterns in aerosol component contributions to haze

  18. Backtrajectory analysis • Gather backtrajectory endpoint data • Compute and map backtrajectory summary statistics residence time by season, best 20% and worst 20% reconstructed extinction and aerosol components for all sites with 5 years or more of data. • Prepare conditional probability maps for high and low extinction and aerosol components. • Interpret maps using emissions density, location information, site setting information • Mesoscale meteorological analysis needed for many sites –backtrajectories will be misleading

  19. Phase 1 conceptual model and virtual report • Develop preliminary conceptual models regarding the sources of haze at every Class I area in the WRAP region; • Note uncertainties and limitations of the conceptual models; • Suggest methodologies to refine conceptual models in next phase of study • Make information available over Internet as “virtual report”

  20. Subsequent phases • Compile additional meteorological, gaseous, aerosol, emissions, and source profile data as needed to complete remaining tasks • Episode analysis -Use combination of backtrajectory, synoptic, mesoscale meteorological analysis, aerosol and emissions data to conceptually understand regional or sub-regional episodes of high aerosol component concentrations

  21. In-depth meteorological analysis • Mesoscale flow patterns affecting sites • Cluster analysis to group days with similar patterns and examine aerosol components for each cluster • Interannual variability of meteorological patterns • Diurnal variations in flow patterns, comparison with diurnal variation in optical data.

  22. Emissions changes and receptor modeling • Evaluation of changes in emissions since 1988 and relationship to aerosol component concentration changes • Source profile analysis- compile source profiles- note changes over time since 1988 • Establish chemical abundances against which enrichment factors can be evaluated • Use carbon fractions from TOR analysis –can contributions of different carbon sources be distinguished?

  23. Emissions changes and receptor modeling -continued • Apply Chemical MassBalance (CMB) model • Apply Positive Matrix Factorization (PMF) at sites with sufficient periods of record of aerosol data • Apply UnMix model to aerosol data for each site with sufficient data

  24. Trends and comprehensive assessment • Statistical significance tests to determine significance of trends in component concentrations • Interpret trends in light of trends in emissions and interannual variability of meteorological patterns- Trend due to emissions or meteorological changes? • Comprehensive assessment of causes of haze- all Class I areas-formulation of refined conceptual models applicable to all WRAP Class I areas • Web-based virtual report

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