1. Modeling Regional Haze in Big Bend National Park with CMAQ Betty Pun, Christian Seigneur & Shiang-Yuh Wu AER, San Ramon Naresh Kumar EPRI, Palo Alto CMAQ Workshop, October 2002

2. BRAVO Study Investigation of the probable causes of visibility degradation in Big Bend National Park, Texas Field study from July to October 1999 Measurements of aerosols and precursors at 40 sites Source modeling conducted with 3-D Eulerian models (CMAQ and REMSAD) and Lagrangian models

3. CMAQ Modeling Domain

4. CMAQ Simulations Two episodes –5-15 October 1999 –10-25 August 1999 Meteorology –Nested MM5 simulations with FDDA conducted by Nelson Seaman, Penn State Emissions –Inventory developed by Hampden Kuhns, DRI –CMAQ inputs prepared with SMOKE by MCNC

5. CMAQ Simulations Initial and Boundary Conditions (IC/BC) –BC developed from IMPROVE network data –IC developed from BRAVO network data –Temporal interpolation conducted for the BC using the results of the coarse grid REMSAD simulation

6. Meteorological Inputs Wind Flow on October 7 at 3 p.m.

7. Emissions of Sea Salt Sodium

8. October Episode, 4-km and 12-km Simulations, Time Series Sulfate (  g/m 3 ) at Big Bend

9. October Episode, 4-km and 12 km Simulations, Regression Analysis Sulfate (  g/m 3 ) at Big Bend 4-km simulation 12-km simulation

10. October Episode, 12-km Simulation Regression Analysis Sulfate (  g/m 3 ), 39 Sites

11. O 3 at 2 p.m. on 11 & 12 October

12. Sulfate at 2 p.m. on 11 & 12 October

13. PM 2.5 at 2 p.m. on 11 & 12 October

14. Chemical Composition at Big Bend 12 October 1999

15. CMAQ Performance First performance evaluation for a regional PM model with a comprehensive database (daily speciated data with good spatial coverage) Performance for October PM simulation is satisfactory, at least for Big Bend National Park Performance for August PM simulation is not satisfactory; sensitivity to boundary conditions is being investigated using REMSAD results to provide better temporal resolution

16. Ongoing Simulations August simulation 100% reduction in SO x emissions from –Mexico –Texas –Other states 50% reduction in NO x, VOC and CO emissions from –Mexico –Texas –Other states Comparison between CMAQ and REMSAD