AAAR 37th Annual Conference October 14 - October 18, 2019 Oregon Convention Center Portland, Oregon, USA
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Emission and Evolution of Submicron Aerosol Composition in Wildfire Smoke in the Western United States
LAUREN GAROFALO, Ezra Levin, Matson A. Pothier, Sonia Kreidenweis, Delphine K. Farmer, Colorado State University
Abstract Number: 505 Working Group: Biomass Combustion: Emissions, Chemistry, Air Quality, Climate, and Human Health
Abstract The number and intensity of wildfires in the western United States is increasing, and the relative impact of emissions from wildfire on regional and global atmospheric composition is becoming more significant. However, aerosol emissions from wildfire are poorly understood and difficult to quantify due to variability in environmental and fire conditions that impact particle emissions. Measurements of particles from wildfire inherently occur downwind of the fire, and can be influenced by chemistry and dilution effects in the near field where smoke is less than 2 hours old. This dilution and chemistry continues as a wildfire plume evolves and is transported. Here, we investigate the emissions, evolution, and chemistry of aerosol from wildfires in the near field with data from the Western Wildfire Experiment for Cloud Chemistry, Aerosol Absorption, and Nitrogen (WE-CAN). We describe the chemical composition of submicron, non-refractory aerosols in the dynamic environment of wildfire smoke plumes as measured by high-resolution time-of-flight aerosol mass spectrometry (HR-TOF-AMS; Aerodyne, Inc). We also discuss black carbon (BC) as measured by single particle soot photometry (SP2; Droplet Measurement Technologies). Organic aerosol (OA), inorganic aerosol, and BC emissions vary due to fuels and fire conditions, which can differ not only across different fires, but also within a single wildfire. These primary emissions evolve as the plume is simultaneously diluted by background air leading to dilution-driven evaporation and photochemical aging. Specifically, we will discuss the emission and evolution of inorganic species (NH4+, SO42-, Cl-, NO3-) in submicron aerosol in wildfire smoke plumes. Characterizing aerosol emissions from wildfires and how chemical oxidation and physical dilution compete in the smoke plume is crucial to understanding the effects of particle emissions from wildfire on air quality and climate.