A225-0007
Spatially resolved oxidation chemistry of reactive organic compounds in wildfire plumes

Wednesday, 16 December 2020
Poster
Joel A Thornton1, Brett B Palm1, Qiaoyun Peng2, Carley Fredrickson1, Ben Lee1, Zachary Decker3, Lauren Garofalo4, Matson A Pothier4, Sonia M Kreidenweis5, Delphine Farmer4, Rudra Pokhrel6, Shane M Murphy7, Wade Permar8, Lu Hu9, Teresa Lynn Campos10, Samuel R Hall11, Kirk Ullmann12, Frank M Flocke13, Emily V Fischer5, Michael A Robinson14, Alessandro Franchin15, Katherine Lynne Hayden16, Ann Middlebrook17 and Steven S Brown18, (1)University of Washington Seattle Campus, Department of Atmospheric Sciences, Seattle, WA, United States, (2)University of Washington Seattle Campus, Department of Atmospheric Sciences, Seattle, CA, United States, (3)NOAA Chemical Sciences Division, Boulder, CO, United States, (4)Department of Chemistry, Colorado State University, Fort Collins, CO, United States, (5)Colorado State University, Atmospheric Science, Fort Collins, CO, United States, (6)University of Wyoming, Laramie, United States, (7)University of Wyoming, Laramie, WY, United States, (8)University of Montana, Chemistry and Biochemistry, Missoula, MT, United States, (9)Univ of MN-Soil, Water, & Clim, St. Paul, MN, United States, (10)Natl Ctr Atmospheric Research, Boulder, CO, United States, (11)NCAR, Denver, CO, United States, (12)National Center for Atmospheric Research (NCAR), Atmospheric Chemistry Observations and Modeling Laboratory, Boulder, CO, United States, (13)NCAR, Boulder, CO, United States, (14)CIRES and NOAA ESRL, Chemical Sciences Laboratory, Boulder, CO, United States, (15)NOAA Earth System Research Laboratory, Chemical Sciences Division, Boulder, CO, United States, (16)Environment and Climate Change Canada, Air Quality Research Division, Toronto, ON, Canada, (17)NOAA Boulder, Boulder, CO, United States, (18)NOAA Earth System Research Laboratory, Chemical Sciences Laboratory, Boulder, CO, United States
Abstract:
The emissions and evolution of wildfire smoke was investigated with a variety of high time-resolution measurements during two recent flight-based measurement campaigns, aboard the NSF/NCAR C-130 during WE-CAN in 2018 and aboard the NOAA Twin Otter during FIREX-AQ in 2019. Using measurements of a variety of oxidized organic compounds as well as nitrous acid (HONO, often the dominant oxidant source) from an iodide-adduct chemical ionization mass spectrometer (I-CIMS), we illustrate the spatial heterogeneity of oxidation chemistry that can be found in daytime wildfire plumes. In general, the dilution-corrected concentrations of highly reactive organic compounds such as phenol and catechol react away fastest on the edges and top of plumes, where oxidation products are likewise enhanced. This is likely due to higher oxidant concentrations on plume edges/top due to enhanced photolysis of oxidant sources such as HONO in more dilute smoke. We use the measurements of such reactive compounds to estimate oxidant concentrations and gradients within plumes. By comparing with measurements from other high time-resolution instruments, we investigate how the spatially variable oxidant concentrations affect physico-chemical processes such as secondary aerosol formation and brown carbon evolution. Measurements of plume evolution during nighttime from the FIREX-AQ campaign are used to illustrate the contrasting spatially resolved plume evolution that occurs in the absence of OH radicals. Lastly, we investigate how this spatially resolved chemistry could impact the interpretation of plume evolution when using spatially resolved measurements versus transect-averaged measurements to compare against models.
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