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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

Causes of Haze Assessment

Mark Green

Desert Research Institute

Marc Pitchford, Chair

Ambient Monitoring & Reporting Forum

causes of haze assessment goals objectives
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
causes of haze assessment approach
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


Causes of Haze Questions

Each Analysis Method Addresses 1 or More of the Questions


Data Analyses

Separate Review & Posting for Each Analysis & Question


Review Draft Results


Post Final Results on Web

Causes of Haze Assessment Process

causes of haze assessment questions
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?
causes of haze assessment questions continued
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?
causes of haze assessment questions continued9
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?
causes of haze assessment questions continued10
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?
causes of haze assessment questions continued11
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?
assessment approach
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
period of record for improve protocol sites in wrap region
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
prepare emissions density maps
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
describe monitoring sites
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.
assess meteorological setting of sites
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.
aerosol data analysis
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
backtrajectory analysis
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
phase 1 conceptual model and virtual report
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”
subsequent phases
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
in depth meteorological analysis
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.
emissions changes and receptor modeling
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?
emissions changes and receptor modeling continued
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
trends and comprehensive assessment
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