1. WRAP Regional Modeling Assessment for Ozone John Vimont

2. WRAP Modeling Constraints Focus on PM and how it affects visibility Coarse Grids (36 or 12 km) Ozone evaluated as indicator of performance – doesn’t get NAAQS level of scrutiny CMAQ does 1-way nesting – may need finer resolution in urban areas to get effect beyond area

3. Chemical Mechanisms Original WRAP runs used CB4 –Not considered as appropriate as others for regional modeling –Tuned toward hi-NO X in urban areas WRAP looking at sensitivity of newer chemical mechanisms –SAPRC99 & CB4-2000

4. SAPRC99 vs. CB4 O3; AQS FE%FB% SAPRC9949.0-48.9 CB451.0-50.9 CB4-200249.2-49.1 cross comparisons

5. Difference? Very little difference in performance Should break out different geographic areas for further evaluation Fast solver for mechanism drives choice –Being implemented for other mechanisms

6. How Best To Use WRAP O 3 ? Evaluate secondary effects of PM strategies Evaluate potential source areas for elevated O 3 levels Use as tool for EIS work – already set up as cumulative analysis tool –Will development increase O 3 ? Use as boundary for 1-way nests for urban-scale analyses –Denver’s how much coming from outside area