1. Causes of Haze Assessment Brief Overview and Status Report
WRAP Attribution of Haze Workgroup
March 29, 2004 San Diego

2. COHA Approach
Determine causes of haze at WRAP and CENRAP Class I areas, WRAP Tribal Class I areas and selected CENRAP IMPROVE protocol sites (includes some tribal areas) 5

3. Questions addressed by COHA
What aerosol components are responsible for haze?
What is meteorology’s role in the causes of haze?
What are the emission sources responsible for haze?
Are there detectable &/or statistically significant multi-year trends in the causes of haze?

4. Use weight of evidence approach to form conclusions regarding the causes of the haze
Complete set of descriptive analyses, maps, other graphics for aerosol composition, spatial, temporal variation, emissions, land use, topographic effects, transport patterns, local wind patterns etc
Do episode analyses to determine likely causes of haze for various commonly and uncommonly occurring conditions
Using above resources form conceptual models of causes of haze and assign quantitative number based on frequency of occurrence of conditions

5. Causes of Haze likely to be segregated by compound of interest, e. g
Causes of Haze likely to be segregated by compound of interest, e.g. sulfate and by geographic area- by source type as possible
Example- Sulfate causes 50% of aerosol haze at Area A- 60% of which is generated within the WRAP area, mainly in the states of B,C,D , 20% is transported into the RPO from states to the east of WRAP and mainly in summer, and 20% from other countries (mostly Country F). Based upon emissions inventory, it is estimated that 80% of the sulfate haze is due to source type G.
Nitrate is X % of the haze, 50% of which……..
Carbon, coarse mass- probably more difficult

6. Completed products
Aerosol analysis or POR completed for all sites with one or more years of data
Backtrajectory analysis to all backtrajectories calculated (Finalizing display methods)
“Hazagon” animation maps for

7. Example backtrajectory map- Big Bend 20% worst days

8. Nearly completed
Map galleries- emissions regional & nearby; local terrain, land use, AQ/met stations, etc.

9. Started
Meteorological characterization of sites- 51 sites completed- finished for CO, NM, AZ, UT, SD, ND- expected completion- May 2004
Maps for backtrajectories- monthly and annual residence time, best, worst case days, concentration weighted residence time- expected completion May 2004
Episode analyses- 8 completed

10. Not yet started
Documentation of conceptual models- major effort this summer after supporting information is developed
Receptor modeling
Trends analysis
Detailed meteorological sites as needed
Refinement of conceptual models

11. Future Phases
Evaluation of EDAS wind field used for backtrajectory analysis – when adequate, when misleading- possible use of MM5 or diagnostic wind fields for trajectory analysis for some sites
Mesoscale meteorological analysis – trajectory analysis? Needed for sites in complex/coastal settting affected by mesoscale source areas
Triangulation of backtrajectories for worst case days to better identify source areas
Regression analysis of backtrajectories, aerosol data for quantitative attribution to regions- Trajectory Mass Balance Regression
Refinement of conceptual models

12. Recent additions to COHA contract
Assessments for tribal areas
In-depth assessment of dust impacts

13. Proposed approach for Tribal Causes of Haze Assessment
Full COHA analysis for 5 Tribal Class I areas-
For large number of remaining tribal lands, form groups based upon geographic proximity and similarity for meteorology, emissions, etc.
Determine availability of representative IMPROVE data
Use existing IMPROVE sites/ representative Class I areas to infer regional causes of haze for groups of tribal lands as possible
Recommend additional monitoring locations as needed unrepresented tribal lands

14. Assessment of the Major Causes of Dust-Resultant Haze in the WRAP
Focus on periods when dust was the principal contributor to haze during worst days
Aim to assign individual worst dust days at an IMPROVE site within WRAP to one of a set of source classes
Much effort to focus on methodology development
Use methodology to categorize worst dust days in the WRAP domain over the period 2001 – 2002

15. Preliminary dust source types
Transcontinental Events
Regional Windblown Events
Local Windblown Dust
Wildfire-Related Events
Other Events- e.g. road dust, construction, mining, agriculture, sea-spray
Unknown
Analysis to be completed by end of 2004