Causes of Haze Assessment

Dave DuBois

Desert Research Institute

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 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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Washington

Montana North Dakota

South Dakota

Wyoming

IdahoOregon

Nevada Utah

California

Colorado

Arizona

New Mexico

Minnesota

Iowa

Nebraska

Kansas Missouri

Oklahoma

Texas

Arkansas

Louisiana

500 0 500 Kilometers

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CENRAP states#S IMPROVE sites

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Alaska

Washington

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Hawaii

Causes of Haze Study Sites

Grand Canyon

Mount Rainier

Lost Wood

etc.

Question 1a

Question 1b

Question 1c

Question 1d

Question 2a

etc.

Each Question is Addressed at Each Class I Areas

Method 1

Method 2

Method 3

etc.

Question 1a

Question 1b

Question 1c

Question 1d

Question 2a

etc.

Each Analysis Method Addresses One or More 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 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 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 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 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

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 <3 years of data Descriptive analyses, trajectory analyses, episode

analysis, cluster analysis, factor analysis, receptor modeling, statistical tests

2 Meteorology & Haze

Descriptive Trajectory Episode Cluster Factor Receptor Modeling

Statistical Tests

2a. Meteorology for best, middle, worst days

Climatology of haze – mesoscale, synoptic scale factors

Residence time, conditional probability

Meteorology

2b. Empirical relationships between meteorology and haze

Wind speed/direction, RH, precipitation and haze

Similar Days (wind fields, trajectories)

Wind fields

-2c. Exp lain best & worst days by meteorological factors

Extinction rose Frequency of clusters

2d. Site characteristics & relationship between meteorology & haze

Site meteorology

Meteorological based site clustering

2e. Interannual variation in haze & meteorology

Year-to-year Residence time variation

Year-to-year variation in met. cluster frequency

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)

Federal Wildland Fire Occurrence Records 1970-2000

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

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.

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 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

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”

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

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

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

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

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