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This study focuses on the development of wildland smoke marker emissions maps for the conterminous United States. It examines the relationship between smoke marker emissions and vegetation type, and explores the use of source profiles in accurately apportioning wildfire smoke. The study also analyzes the impact of fires on air pollution and the health effects associated with smoke. The findings provide valuable information for understanding and managing wildfires.
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Development of Wildland Smoke Marker Emissions Maps for the Conterminous United States Leigh Patterson 06/15/09 M.S. Defense
Acknowledgements • Advisor: Dr. Jeff Collett • Committee: Drs. Kreidenweis, Schichtel, and Rocca • FLAME Partners: Cyle Wold, Dr. Wei Min Hao, Dr. Bill Malm • Sample Analysis: Amy Sullivan, Mandy Holden • Funding: Joint Fire Science Program, National Park Service, American Meteorological Society • Friends and family
Outline • Introduction & motivation • Fire Lab at Missoula Experiment (FLAME) • Relationship between smoke marker emissions and vegetation type • Fuel Characteristic Classification System • Smoke marker emissions maps • Biomass burning carbon apportionment
Fire Impacts • Radiative budget • OC – reflective • EC – absorptive • Visibility • Regulated by Clean Air Act • Wildfires – natural • Prescribed fires – manmade • Health effects • Ultra-fine particles provoke alveolar inflammation (Seaton 1995) • During a fire episode in California, 117 hospital admissions for smoke reactions (Shusterman et. al., 1993)
Effects of fires on air pollution Total TC – IMPROVE measurements TC enhancement TC, µg m-3 Park et. al, 2007 Debell et. al., 2006
What are smoke markers? • Chemical compounds used to fingerprint smoke • K+ • Produced from loss of potassium in plant matter (Arianoutsou and Margaris, 1981) • Anhydrosugars • Includes levoglucosan, mannosan, and galactosan • Produced from combustion of cellulose and hemicellulose • Marker criteria: unique, constant, inert, and measurable (Khalil and Rasmussen, 2003)
Why do we need accurate source profiles? • MM-CMB models use profiles to apportion wildfire smoke • CMB models attempt to apportion 100% of the PM to various sources • If one source is incorrectly apportioned, the apportionment of other sources will be misestimated • Correct geographic profiles are most important to determine wildfire smoke contribution (Sheesley et. al., 2007)
Why do we need accurate source profiles? • MM-CMB models use profiles to apportion wildfire smoke • CMB models attempt to apportion 100% of the PM to various sources • If one source is incorrectly apportioned, the apportionment of other sources will be misestimated • Correct geographic profiles are most important to determine wildfire smoke contribution (Sheesley et. al., 2007)
FLAME Study • Burned over 33 fuels in over 100 burns in two campaigns in a burn chamber in Missoula, MT • Mostly single component burns • Measured physical, optical and chemical properties Picture courtesy of Gavin McMeeking
Vegetation Relationship Levoglucosan/OC Cellulose dry mass Sullivan et. al., 2008 Hoch, 2007
Vegetation composition & anhydrosugar relationship Levoglucosan & Cellulose Mannosan/Galactosan & Hemicellulose
Vegetation source profiles FLAME groups Non-FLAME groups • Separate vegetation groups • Source profile = median profile of each group • Averages have outlier problems • Problem: The FLAME study does not sample all different types of vegetation in the U.S. • Identify source profiles in lit • Take median of each study • Average the medians to calculate final source profile
Fuel Characteristic Classification System • Fully descriptive fuelbed model • Defines 113 fuelbeds across U.S. • Assigns characteristics for six strata in each fuelbed • Maps fuelbeds across conterminous U.S. with 1 km resolution Ottmar et. al., 2007
Emissioni = Emissioni = Emissions Algorithm Emissionsi = • Bj = fuel loading • CEj = combustion efficiency • eij = emissions factor (source profile) • Canopy (3 stories): • Hardwood branches • Softwood branches • Hardwood leaves • Softwood needles • Shrubs • Shrub branches • Shrub leaves • Non-woody vegetation • Grasses • Litter • Duff
Source Profiles • Litter: 5 different categories are multiplied with weightings • Duffs are assigned same source profile as litters
Duff: Calculated vs. Measured • Calculated levoglucosan yields match measured • Mannosan and galactosan are underestimated • K+ is grossly overestimated • Burn conditions • Correction factor of 2.65 is applied
Can a national source profile apply? Levoglucosan/OC Mannosan/OC
Source Apportionment • Samples from IMPROVE site in Rocky Mountain National Park • Weekly: 06/28/05 – 08/16/05 • Attempts to apportion carbon resulted in overestimation of biomass burning carbon concentrations Carbon concentrations and biomass burning carbon concentration courtesy of Amanda Holden
Simple Fire Model • Fires identified by MODIS thermal anomalies • Seven 48 hour HYSPLIT back trajectories were calculated • Source profiles of fires within 2 degrees latitude and 2 degrees longitude of a trajectory were averaged • No accounting for fire size, distance to sampler, or dispersion
New Source Apportionment • Estimates using levoglucosan source profile improved • K+ and galactosan source profiles yield reasonable results • Mannosan too high • Uncertainty can be assessed
New Source Apportionment • Estimates using levoglucosan source profile improved • K+ and galactosan source profiles yield reasonable results • Mannosan too high • Uncertainty can be assessed
Vegetation composition & anhydrosugar relationship Differences in means of different vegetation types Source profiles Vegetation Fuelbed Fuelbed profile maps Source apportionment In summary
Grouping vegetation types • Sullivan et. al. – 6 groups • Grasses • Leaves • Needles • Branches • Straws • Duffs Shrub Leaves Hardwood Leaves Shrub Branches Softwood Branches
Physical Fuel Loadings • Canopy: • Split into hardwoods and softwoods • Hardwoods: 84% wood, 16% leaves (Wiedenmyer et. al., 2006) • Softwoods: 79% wood, 21% needles (Wiedenmyer et. al., 2006) • Shrub: • 39% wood, 61% leaves (Wiedenmyer et. al., 2006)
Smoke Contribution • Canopy: • Combustion efficiencies: 30% for wood, 90% for leaves/needles (Wiedenmyer et. al., 2006) • Hardwoods: 64% wood, 36% leaves • Softwoods: 56% wood, 44% needles • Shrub: • Combustion efficiency: 30% for wood, e(-.013*TCP) for leaves(Wiedenmyer et. al., 2006) • For 50% shrub coverage: 27% wood, 73% leaves
Combustion efficiencies • Canopy: Total trees available to fire depends on fire characteristics. Combustion efficiency: 0.9 for leaves, 0.3 for wood (Wiedenmyer et. al. 2006) • Shrub: 0.3 for wood, CE = exp(-0.013*TCP) for leaves (Wiedenmyer et. al. 2006) • Non-woody vegetation: 0.98 (Wiedenmyer et. al. ,2006) • Litter-lichen-moss: 1 (Reinhardt et. al. 2003) • Ground fuels: CE = (26.1 – 0.225 * DM + 0.0417 * DEPTH)/DEPTH (Brown et. al. 1985)
Source Profiles Sheesley et. al. 2007