Downwind Measurements of Wildfires with Varying Burn Conditions: Flaming vs. Smoldering Emissions
Friday, 19 December 2014
During July and August of 2013 two sampling platforms were utilized to probe the physical and chemical properties of wildfire emissions in the Pacific Northwest area of the U.S. during the Department of Energy (DOE) sponsored Biomass Burning Observation Project (BBOP). Continuous ground measurements were taken at the Mt. Bachelor Observatory (MBO) including non-refractory (NR) PM1 size-resolved chemical composition using a High Resolution Time-of-Flight Aerosol Mass Spectrometer (AMS), aerosol light scattering using a Nephelometer, and gas-phase CO, CO2, O3, NOx, and NOy measurements. A similarly equipped sampling platform was launched aboard the Gulfstream-1 (G-1) aircraft which flew near wildfires to probe near-source emissions. Sixteen well-defined fire plumes observed at MBO were selected for detailed analysis and calculation of the modified combustion efficiency (MCE), a quantitative measure of burning conditions. The analyses include calculation of enhancement ratios relative to CO and CO2, elemental ratios of organic aerosols, and back-trajectory analysis for approximate plume age and fire source location. Strong trends were observed when comparing dilution corrected aerosol parameters vs MCE for all plumes identified. Organic PM, scattering and particle-phase inorganic nitrate enhancements displayed a negative correlation with increasing MCE. Various plumes from the G1 data set were analyzed using the same criteria and consistencies were found. We will explore the potential role that burning conditions have on wildfire emissions and how these may be used for better modeling and more accurate emissions inventories.