WRAP Regional Modeling Assessment for Ozone

John Vimont

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

Chemical Mechanisms

• Original WRAP runs used CB4– Not considered as appropriate as others for

regional modeling

– Tuned toward hi-NOX in urban areas

• WRAP looking at sensitivity of newer chemical mechanisms– SAPRC99 & CB4-2000

SAPRC99 vs. CB4O3; AQS

FE% FB%

SAPRC99 49.0 -48.9

CB4 51.0 -50.9

CB4-2002 49.2 -49.1

cross comparisons

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

How Best To Use WRAP O3?

• Evaluate secondary effects of PM strategies• Evaluate potential source areas for elevated O3

levels• Use as tool for EIS work – already set up as

cumulative analysis tool– Will development increase O3?

• Use as boundary for 1-way nests for urban-scale analyses– Denver’s how much coming from outside area