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

Center for Environmental Research and Technology/Environmental Modeling University of California at Riverside Fire Plume Rise Modeling Project Status Today’s Presentation –Project Objectives –Plume Rise Modeling Methods –Fire Events Modeled –Results –Summary

Center for Environmental Research and Technology/Environmental Modeling University of California at Riverside Acknowledgments Tom Moore and FEJF – project design Air Sciences - Emissions Inventory

Center for Environmental Research and Technology/Environmental Modeling University of California at Riverside Fire Plume Rise Modeling Project Objectives Compare the plume rise and the vertical emissions distribution for fires, using to methods: 1.The FEJF Approach 2.The SMOKE-Briggs Approach

Center for Environmental Research and Technology/Environmental Modeling University of California at Riverside Model vertical layer structure CMAQ has 19 vertical layers: –Layer 1: m –Layer 2-5: m –Layer 6-10: m –Layer 11-14: m –Layer 15-16: m –Layer 17-19: ,662 m

Center for Environmental Research and Technology/Environmental Modeling University of California at Riverside  Plume Top hour = (BE hour ) 2 * (BE size ) 2 * Ptop max  Plume Bottom hour = (BE hour ) 2 * (BE size ) 2 * Pbot max  Layer1 Fraction hour = 1 – (BE hour * BE size ) BE size = fire size-dependent buoyancy efficiency Be hour = hourly buoyancy efficiency Pbot max = maximum height of the plume bottom Ptop max = maximum height of the plume top BE size, Ptop max Pbot max, and BE hour are provided in the FEJF Phase II fire report (Air Sciences, Inc., 2006). 1.FEJF Approach Plume Rise Modeling Methods

Center for Environmental Research and Technology/Environmental Modeling University of California at Riverside Plume Buoyancy Efficiency, F (m 4 /s 3 ), as follows.  F = Q * Q = Heat Flux (btu/day), Buoyant Efficiency (BE size )  BE size = * ln(acres) Smoldering Fraction (S fract )  S fract = 1 – BE size NOTE: possible bug in implementing smoldering fraction in SMOKE. We expect a larger fraction of emissions in layer 1 in SB. 2.SMOKE-Briggs Approach (SB)

Center for Environmental Research and Technology/Environmental Modeling University of California at Riverside Heat Flux from FEPS Fire Emissions Productions Simulator (FEPS) was used to determine heat flux: –FEPS was developed by Anderson et al. –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.

Center for Environmental Research and Technology/Environmental Modeling University of California at Riverside Fire TypeStateDate Fire Size (Acres) Daily Emissions (tons/day) Heat Flux (btu/day) COPM2.5NOxVOC WFU 1 COJuly ,530,000,000 RX 2 AZNov ,320,000,000 WF 3 AZJune ,036,600,000,000 RXORSep ,030,000 WFORAug ,293.82, ,190.32,237,008,255,600 1 WFU= wildland fire use 2 RX=prescribed fire 3 WF=wildfire Fire Events

Center for Environmental Research and Technology/Environmental Modeling University of California at Riverside FEJF fire Characteristics Oregon Prescribed Fire PBOT = Plume Bottom PTOP = Plume Top LAY1F = Emissions fraction in Layer 1

Center for Environmental Research and Technology/Environmental Modeling University of California at Riverside FEJF fire Characteristics Oregon Wild Fire

Center for Environmental Research and Technology/Environmental Modeling University of California at Riverside Hourly Emissions per Layer Colorado Wild Fire

Center for Environmental Research and Technology/Environmental Modeling University of California at Riverside Hourly Emissions Distribution Colorado Wild Fire

Center for Environmental Research and Technology/Environmental Modeling University of California at Riverside Hourly Emissions per Layer Arizona Prescribed Fire

Center for Environmental Research and Technology/Environmental Modeling University of California at Riverside Hourly Emissions Distribution Arizona Prescribed Fire

Center for Environmental Research and Technology/Environmental Modeling University of California at Riverside Hourly Emissions per Layer Arizona Wild Fire

Center for Environmental Research and Technology/Environmental Modeling University of California at Riverside Hourly Emissions Distribution Arizona Wild Fire

Center for Environmental Research and Technology/Environmental Modeling University of California at Riverside Hourly Emissions per Layer Oregon Prescribed Fire

Center for Environmental Research and Technology/Environmental Modeling University of California at Riverside Hourly Emissions Distribution Oregon Prescribed Fire

Center for Environmental Research and Technology/Environmental Modeling University of California at Riverside Hourly Emissions per Layer Oregon Wild Fire

Center for Environmental Research and Technology/Environmental Modeling University of California at Riverside Hourly Emissions Distribution Oregon Wild Fire

Center for Environmental Research and Technology/Environmental Modeling University of California at Riverside Daily Emissions Fractions per Layer CO FEJF: 45% in surface layer, 45% above 2462 m. CO SB: most emission between m.

Center for Environmental Research and Technology/Environmental Modeling University of California at Riverside Results 1.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. 2.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. 3.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.

Center for Environmental Research and Technology/Environmental Modeling University of California at Riverside Conclusions 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.

Center for Environmental Research and Technology/Environmental Modeling University of California at Riverside Conclusions (2) 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.