A234-05
Evolution of Brown Carbon Aerosol Absorption Downwind of Wildfires in the Western U.S.

Wednesday, 16 December 2020: 07:16
Virtual
Rebecca A Washenfelder1, Lisa Azzarello2, Kat Ball3, Steven S Brown4, Zachary Decker5, Alessandro Franchin6, Carley Fredrickson7, Katherine Lynne Hayden8, Christopher D Holmes9, Ann Middlebrook1, Brett Palm10, Michael A Robinson11, Joel A Thornton12 and Cora Young13, (1)NOAA Boulder, Boulder, CO, United States, (2)York University, Department of Chemistry, Toronto, ON, Canada, (3)University of Maryland, Baltimore County, Baltimore, MD, United States, (4)NOAA Earth System Research Laboratory, Chemical Sciences Laboratory, Boulder, CO, United States, (5)NOAA Chemical Sciences Division, Boulder, CO, United States, (6)NOAA Earth System Research Laboratory, Chemical Sciences Division, Boulder, CO, United States, (7)University of Washington Seattle Campus, Department of Atmospheric Sciences, Seattle, WA, United States, (8)Environment and Climate Change Canada, Air Quality Research Division, Toronto, ON, Canada, (9)Florida State University, Tallahassee, FL, United States, (10)University of Washington Seattle Campus, Atmospheric Sciences, Seattle, United States, (11)CIRES and NOAA ESRL, Chemical Sciences Laboratory, Boulder, CO, United States, (12)University of Washington, Department of Atmospheric Sciences, Seattle, WA, United States, (13)Memorial University of Newfoundland, St John's, NF, Canada
Recorded Presentation
Abstract:
Wildfires are a major source of brown carbon (organic aerosol that absorbs strongly in the ultraviolet and visible spectral regions) in the United States and globally. The lifetime and chemical aging of brown carbon from wildfires are important, but poorly known. We sampled wildfires in the Western U.S. during August 2019 on the NOAA Twin Otter aircraft as part of the Fire Influence on Regional to Global Environments and Air Quality (FIREX-AQ) field campaign. We measured brown carbon absorption using a particle-into-liquid sampler coupled to a liquid waveguide capillary cell. We report the lifetime of brown carbon observed in downwind transects of eleven fire plumes, representing transport times of 0.5 – 10 hours. We do not observe rapid loss of brown carbon for these transects. We examine the chemical aging of brown carbon and the implications for the radiative impact of biomass burning smoke.
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