TemplateTemplate

Evaluation of an Advanced Reactive Puff Model using

Aircraft-based PlumeMeasurements

Krish Vijayaraghavan, Prakash Karamchandani, Bart Brashers, Shu-Yun Chen, Greg Yarwood, Sue

Kemball-CookENVIRON International Corporation, Novato, CA

Biswanath Chowdhury - Sage Management, Princeton, NJ

Eladio Knipping - EPRI, Washington, DC

9th Annual CMAS Conference, October 11-13, 2010

Chapel Hill, North Carolina

2

Outline

• Model Description

• Objective

• Model Inputs and Application

• Aircraft Traverses and Model Receptors

• Performance Evaluation

• Conclusions and Recommendations

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

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.

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

Model Inputs and Application• Simulation performed for 8 September 2005• Hourly emissions of SO2 and NOx 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

Aircraft Traverses and Model Receptors

8

Comparison with Aircraft Measurements

9

Comparison with Aircraft Measurements

10

Comparison with Aircraft Measurements

11

Comparison with Aircraft Measurements

12

Performance Statistics Ozone

13

Performance Statistics NOx

14

Performance Statistics NOy

15

Performance Statistics SO2

16

SCICHEM Evaluation in a Prior Application

Source: Karamchandani et al. 2000. Environ. Sci. Technol., 34, 870-880.

Comparison with helicoptermeasurements of Cumberland

power plant plume

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?

Acknowledgments

This work was conducted under EPRI sponsorship

Questions?