Causes of Haze Assessment

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Causes of Haze Assessment

• Dave DuBois
• Desert Research Institute

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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

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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

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Causes of Haze Study Sites
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Each Question is Addressed at Each Class I Areas
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Each Analysis Method Addresses One or More
Questions
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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?

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Causes of Haze AssessmentQuestions - continued

• What is meteorologys 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?

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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?

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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?

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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?

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Assessment Approach

• Start with basics, sequentially increase
  complexity
• Most thorough effort for 35 WRAP sites with 7 or
  more years data and 4 long-term CENRAP sites
• Reduced set of analyses for remaining 44 WRAP
  sites and 20 CENRAP sites with lt3 years of data
• Descriptive analyses, trajectory analyses,
  episode analysis, cluster analysis, factor
  analysis, receptor modeling, statistical tests

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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
• For CENRAP, need to include emissions east of
  CENRAP (Midwest RPO, VISTAS)

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Federal Wildland Fire Occurrence Records 1970-2000
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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.

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Assess meteorological setting of sites

• Expected mesoscale flow patterns of interest
  (sea/land breeze, mountain/valley winds,
  convergence zones, nocturnal jets, 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.

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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

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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

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Phase 1 conceptual model and virtual report

• Develop preliminary conceptual models regarding
  the sources of haze at every Class I area in the
  WRAP and CENRAP regions 14 additional sites in
  CENRAP
• 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

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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

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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.

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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?

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Emissions changes and receptor modeling -continued

• Apply Chemical Mass Balance (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

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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 14 additional CENRAP
  areas-formulation of refined conceptual models
  applicable to all areas
• Web-based virtual report