1. Template Evaluation of an Advanced Reactive Puff Model using Aircraft-based Plume Measurements Krish Vijayaraghavan, Prakash Karamchandani, Bart Brashers, Shu-Yun Chen, Greg Yarwood, Sue Kemball-Cook ENVIRON International Corporation, Novato, CA Biswanath Chowdhury - Sage Management, Princeton, NJ Eladio Knipping - EPRI, Washington, DC 9 th Annual CMAS Conference, October 11-13, 2010 Chapel Hill, North Carolina

2. 2 Outline Model Description Objective Model Inputs and Application Aircraft Traverses and Model Receptors Performance Evaluation Conclusions and Recommendations

3. Model Description - SCICHEM Second-order Closure Integrated Puff model with Chemistry Three dimensional Lagrangian puff model Plume is represented as a superposition of a series of 3-D Gaussian puffs Uses second-order turbulence closure Dynamic plume-rise calculation based on conservation of energy and momentum Puff-splitting algorithm allows accurate treatment of wind shear Puff merging minimizes number of puffs Efficient adaptive time-step algorithm

4. Model Description - SCICHEM Detailed gas-phase photochemistry based on CB-IV RADM aqueous-phase chemistry scheme Inorganic aerosol thermodynamics (ISORROPIA) Secondary Organic Aerosols (SOA) treatment Sectional PM size distribution with two sections Optional modal PM size distribution SCICHEM can use either routine observations of meteorology and concentrations or modeled 3-D fields.

5. Objective Evaluate SCICHEM using aircraft observations of the plume from the Dolet Hills power plant in NW Louisiana conducted during the Northeast Texas Air Care (NETAC) 2005 Air Quality Study Source: Baylor University Report

6. Model Inputs and Application Simulation performed for 8 September 2005 Hourly emissions of SO 2 and NO x from CAMD Surface and upper-air meteorology from Shreveport, from NOAA Integrated Surface Hourly Observations DVD (ds3505) and the NOAA ESRL radiosonde database Fixed wind direction to best match observed plume direction Constant background chemical environment specified using domain-averages from previous CAMx simulations as well as aircraft data Stack parameters for Dolet Hills Power Plant (in NW Louisiana near the Texas border) –Height = 160 m –Diameter = 7.6 m –Exit Temperature = 70 C –Exit Velocity = 26 m/s

7. Aircraft Traverses and Model Receptors

8. 8 Comparison with Aircraft Measurements

9. 9

10. 10 Comparison with Aircraft Measurements

11. 11 Comparison with Aircraft Measurements

12. 12 Performance Statistics Ozone

13. 13 Performance Statistics NOx

14. 14 Performance Statistics NOy

15. 15 Performance Statistics SO 2

16. 16 SCICHEM Evaluation in a Prior Application Source: Karamchandani et al. 2000. Environ. Sci. Technol., 34, 870-880. Comparison with helicopter measurements of Cumberland power plant plume

17. 17 Conclusions and Recommendations Aircraft observations of plumes provide another dimension to evaluating air quality models SCICHEM was evaluated using aircraft measurements of a power plant plume along the Louisiana/Texas border Model performance statistics are good near the stack and generally reasonable farther away. Model application used readily available data Need to investigate the effects of meteorology and background pollutant concentrations on predicted peak concentrations: can model performance be improved by using 3-D meteorology and concentration fields?

18. Acknowledgments This work was conducted under EPRI sponsorship

19. Questions?