Fire Plume Rise WRAP (FEJF) Method vs. SMOKE Briggs (SB) Method

1. Mohammad Omary, Gail Tonnesen WRAP Regional Modeling Center University of California Riverside Zac Adelman Carolina Environmental Program University of North Carolina Fire Plume RiseWRAP (FEJF) Method vs. SMOKE Briggs (SB) Method Fire Emissions Joint Forum Meeting, October 17-18, 2006, Spokane, WA

2. Fire Plume Rise Modeling Project Status • Today’s Presentation • Project Objectives • Plume Rise Modeling Methods • Fire Events Modeled • Results • Summary

3. Acknowledgments • Tom Moore and FEJF – project design • Air Sciences - Emissions Inventory

4. Fire Plume Rise Modeling Project Objectives Compare the plume rise and the vertical emissions distribution for fires, using to methods: • The FEJF Approach • The SMOKE-Briggs Approach

5. CMAQ has 19 vertical layers: Layer 1: 0 - 36 m Layer 2-5: 36 - 220 m Layer 6-10: 220 - 753 m Layer 11-14: 753 - 1828 m Layer 15-16: 1828 - 3448 m Layer 17-19: 3448 - 14,662 m Model vertical layer structure

6. Plume Rise Modeling Methods • FEJF Approach • Plume Tophour = (BEhour)2 * (BEsize)2 * Ptopmax • Plume Bottomhour = (BEhour)2 * (BEsize)2 * Pbotmax • Layer1 Fractionhour = 1 – (BEhour * BEsize) BEsize = fire size-dependent buoyancy efficiency Behour = hourly buoyancy efficiency Pbotmax = maximum height of the plume bottom Ptopmax = maximum height of the plume top • BEsize, Ptopmax Pbotmax, and BEhour are provided in the FEJF Phase II fire report (Air Sciences, Inc., 2006).

7. SMOKE-Briggs Approach (SB) • Plume Buoyancy Efficiency, F (m4/s3), as follows. • F = Q * 0.00000258 • Q = Heat Flux (btu/day), • Buoyant Efficiency (BEsize) • BEsize = 0.0703 * ln(acres) + 0.03 • Smoldering Fraction (Sfract) • Sfract = 1 – BE size NOTE: possible bug in implementing smoldering fraction in SMOKE. We expect a larger fraction of emissions in layer 1 in SB.

8. Fire Emissions Productions Simulator (FEPS) was used to determine heat flux: FEPS was developed by Anderson et al. http://www.fs.fed.us/pnw/fera/feps/ User specifies the fire name, location, start date, end date, size, fuel type and other properties. FEPS calculates the hourly emissions and heat release. Uncertainty in specifying fire variables in FEPS might affect heat release estimate. Not available in batch mode so difficult to use FEPS in SB. Heat Flux from FEPS

9. Fire Type State Date Fire Size (Acres) Daily Emissions (tons/day) Heat Flux (btu/day) CO PM2.5 NOx VOC WFU1 CO July 14 850 3382.6 282.08 72.57 159.18 82,530,000,000 RX2 AZ Nov. 07 2577 3988.1 332.58 85.56 187.68 268,320,000,000 WF3 AZ June 30 9860 19804.3 1651.5 424.9 931.97 1,036,600,000,000 RX OR Sep. 24 1000 173.4 14.46 3.72 8.16 300,030,000 WF OR Aug. 03 7885 25,293.8 2,109.3 542.6 1,190.3 2,237,008,255,600 1WFU= wildland fire use 2RX=prescribed fire 3WF=wildfire Fire Events

10. FEJF fire CharacteristicsOregon Prescribed Fire PBOT = Plume BottomPTOP = Plume TopLAY1F = Emissions fraction in Layer 1

11. FEJF fire CharacteristicsOregon Wild Fire

12. Hourly Emissions per Layer Colorado Wild Fire

13. Hourly Emissions DistributionColorado Wild Fire

14. Hourly Emissions per LayerArizona Prescribed Fire

15. Hourly Emissions DistributionArizona Prescribed Fire

16. Hourly Emissions per LayerArizona Wild Fire

17. Hourly Emissions DistributionArizona Wild Fire

18. Hourly Emissions per LayerOregon Prescribed Fire

19. Hourly Emissions DistributionOregon Prescribed Fire

20. Hourly Emissions per LayerOregon Wild Fire

21. Hourly Emissions DistributionOregon Wild Fire

22. Daily Emissions Fractions per Layer CO FEJF: 45% in surface layer, 45% above 2462 m. CO SB: most emission between 200 - 1000 m.

23. Results • The FEJF approach places a large fraction of the emissions in the surface layer, and the plume with the remaining emissions are consistently located at higher layers compared to the SB approach. • The plume bottom in FEJF depend on the fire size. It can be as high as several thousand meters above the first layer. In SB the plume bottom is always above the first layer. • On daily basis, most of the emissions are in the first layer in FEJF, while in SB most of the emissions in the mid to upper layers.

24. The SB approach seems unrealistic since smoldering emissions should be located in the first layer. Since emissions occur during the day time when the boundary layer tends to be well mixed, model results might be insensitive to the vertical location of emissions within the boundary layer. To the extent that the FEJF approach locates emissions above the boundary layer, it might have smaller near field impact and greater long range transport. If fires occur at times when the boundary is shallow or poorly mixed, the FEJF approach might have a greater near field impact and less long range transport. Conclusions

25. Air quality modeling using CMAQ or CAMx is needed to determine of the two approaches would have significantly different air quality impacts, however, the current approach using FEPS is not feasible to model a large number of events. Because the differences in near field versus long range transport might depend on the meteorology conditions, it would be necessary to model a large variety of conditions to determine if the choice of FEPS or SB results in consistently different visibility impacts. SB approach would have greater near field impacts than FEJF if SMOKE is modified to locate a larger smoldering fraction in layer 1. Conclusions (2)