1. Weight of Evidence Checklist Review AoH Work Group Call June 7, 2006 Joe Adlhoch - Air Resource Specialists, Inc.

2. Class I Area Profile → WOE Checklist

3. Class I Area Profile on the WRAP Technical Support System (TSS) http://vista.cira.colostate.edu/tss/

4. Draft WOE Checklist (Step 1) Summary of available information  General Class I area information (location, size, topography, discussion of importance, etc.)  Overview summary of basic data sets: Visibility monitoring Emission inventories Modeling results  Will vary according to state (e.g., no CMAQ modeling done for AK; some states have international borders)  Style will be customized by each state

5. Draft WOE Checklist (Step 2) Analysis of visibility conditions  What are current (baseline, 2000-04) visibility conditions? What is the relative importance of each species?  What does the RHR glide path look like? What are estimated natural visibility conditions? What does the model predict for 2018?

6. Baseline Conditions at Sawtooth, ID 20% Worst Vis. Days SpeciesContribution SulfateMedium NitrateLow OrganicsHigh ECMedium CMLow SoilLow

7. Regional Haze Rule Glide Path for Sawtooth Model results for the 2018 base case do not predict Sawtooth’s visibility (in terms of deciview) will be on or below the glide path

8. Draft WOE Checklist (Step 3) Analysis of visibility conditions by individual species  What do individual species glide paths (measured in extinction) look like? Need to define natural conditions appropriately (following examples assume “annual average” natural conditions, not 20% worst) Which species show predicted 2018 values at or below the glide path?

9. Species Glide Paths for Sawtooth symbol represents 2018 model prediction POM, the most significant contributor, does not follow the glide path (CM is shown for reference only)

10. Draft WOE Checklist (Step 4) Review monitoring uncertainties and model performance for each species  What level of monitoring uncertainties are associated with each species? Lab uncertainties (can be calculated from IMPROVE data set Other uncertainties (flow rate problems, clogged filters) may be difficult to quantify  How well does the model predict the monitoring data? Good model performance is most important for highest contributing species What does performance look like seasonally and over all?

11. IMPROVE (top) vs. Model (bottom) Seasonal variations in major species is reasonably similar

12. 2002 Model Performance, Worst Days Carbon somewhat low but reasonable Sulfate, nitrate and soil similar CM shows very poor performance

13. Draft WOE Checklist (Step 5) Integrate information about each species: monitoring, modeling, and emissions data  Do changes in emissions agree with model predictions for 2018? How do we know what source region of emissions to compare? Weight emissions by back trajectory residence times to estimate what emissions have the potential to impact a given Class I area  Do weighted emissions described above support attribution results derived from PSAT and PMF?

14. POM Glide Slope with Weighted Emissions Baseline Extinction with Lab Uncertainty Predicted 2018 Extinction Weighted Emissions

15. POM Glide Slope with Weighted Emissions

16. Calculating Weighted Emissions Potential for a Class I Area X= EmissionsResidence TimesWeighted Emissions Potential Use annual average emissions Use residence times based on 3 – 5 years of 8-day back trajectories (20% worst days or all days) Weight the residence times by 1/distance from Class I area (approximates dispersion and deposition) Very low residence time values have been ignored Results do not take into account chemical reactions (or biogenic VOC emissions for secondary particulate formation)

17. Sawtooth: Primary Organic Aerosol Total POA emissions X residence time = weighted emissions potential Weighted emissions potential represents most probable source region emissions which contribute to POM at the selected monitoring site.

18. Estimating Relative Impacts of Emissions Source Regions The goal is to give states a tool to investigate emissions source regions likely to impact their Class I areas  Review weighted emissions by source region (states)  Review total emissions within 2, 4, and 8 grid cells of the site Ultimately compare results with PSAT and/or PMF analyses

19. Strength of POA Source Regions: Weighted

20. Draft WOE Checklist (Step 6) Investigate specific questions that arise in steps 2 – 6  Review historical trends (if sufficient data exists)  Review distributions of IMPROVE mass, and expected changes predicted by the model  Review natural, episodic events for their potential impact  Do the results so far make sense? If not, deeper investigation of data sets may be required  Are there reasonable explanations for species that show and don’t show progress along the glide path?  Consider the other factors mandated by the RHR to determine reasonable progress

21. Draft WOE Checklist (Step 7) Repeat steps 2 – 6 with emissions and model results from various control strategies  How do specific control strategies affect the outcome?

22. Draft WOE Checklist (Step 8) Review available attribution information and determine which states need to consult about which Class I areas  PSAT will be available for sulfate and nitrate (and possible some portion of organics)  PMF will be available for all species (?), but may be used primarily for carbon and dust  Emissions weighted by residence times will be available for all species (pending certain sensitivity tests and caveats)