A234-02
Chemical transformation of wildfire smoke at the transition from day to night.
Wednesday, 16 December 2020: 07:04
Virtual
Zachary Decker1,2, Michael A Robinson3, Carley Fredrickson4, Brett B. Palm5, Georgios Gkatzelis3, Matthew Mitchell Coggon3, Kelley Barsanti6, Ilann Bourgeois7,8, Frank M Flocke9, Alessandro Franchin10, Alan Fried11, Jessica Gilman12, Samuel R Hall13, Katherine Lynne Hayden14, Christopher D Holmes15, Aaron Lamplugh3, Avi Lavi16, Ann Middlebrook17, Denise Montzka10, Richard Moore18, J A Neuman19,20, Jeff Peischl3, Dirk Richter21, Claire E Robinson18, Andrew W Rollins22, Thomas B Ryerson2, Rebecca Schwantes23, Kenneth Lee Thornhill II18, Geoffrey S Tyndall9, Paul Van Rooy6, Patrick R Veres24, James Walega21, Carsten Warneke3, Rebecca A Washenfelder25, Petter Weibring21, Andrew John Weinheimer26, Elizabeth Brooke Wiggins18, Edward Winstead18, Kevin Sanchez27, Caroline Womack8,28, Joel A Thornton29 and Steven S Brown17, (1)CIRES/ NOAA ESRL, Chemical Sciences Laboratory, Boulder, CO, United States, (2)NOAA Earth System Research Laboratory, Boulder, CO, United States, (3)CIRES and NOAA ESRL, Chemical Sciences Laboratory, Boulder, CO, United States, (4)University of Washington Seattle Campus, Department of Atmospheric Sciences, Seattle, WA, United States, (5)University of Washington, Atmospheric Sciences, Seattle, WA, United States, (6)University of California Riverside, Riverside, CA, United States, (7)NOAA ESRL Chemical Science Division, Boulder, CO, United States, (8)Cooperative Institute for Research in Environmental Sciences, Boulder, CO, United States, (9)NCAR, Boulder, CO, United States, (10)National Center for Atmospheric Research, Boulder, CO, United States, (11)University of Colorado at Boulder, INSTAAR, Boulder, CO, United States, (12)NOAA Earth System Research Laboratory, Chemical Sciences Laboratory, Boulder, CO, United States, (13)NCAR, Denver, CO, United States, (14)Environment and Climate Change Canada, Air Quality Research Division, Toronto, ON, Canada, (15)Florida State University, Tallahassee, FL, United States, (16)South Coast Air Quality Management District, Diamond Bar, United States, (17)NOAA Boulder, Boulder, CO, United States, (18)NASA Langley Research Center, Hampton, VA, United States, (19)Cooperative Institute for Research in Environmental Sciences (CIRES), NOAA ESRL, Chemical Sciences Laboratory, Boulder, CO, United States, (20)NOAA ESRL, Boulder, CO, United States, (21)University of Colorado at Boulder, Institute of Arctic and Alpine Research, Boulder, CO, United States, (22)NOAA Earth System Research Laboratory, Chemical Sciences Division, Boulder, CO, United States, (23)Cooperative Institute for Research in Environmental Sciences (CIRES) University of Colorado and NOAA ESRL Chemical Sciences Laboratory, Boulder, CO, United States, (24)NOAA Earth System Research Lab, Boulder, CO, United States, (25)NOAA ESRL, Chemical Sciences Laboratory, Boulder, CO, United States, (26)NCAR, Atmospheric Chemistry Observations and Modeling Laboratory, Boulder, CO, United States, (27)NASA Langley Research Center, Hampton, United States, (28)CIRES and NOAA Chemical Sciences Laboratory, Boulder, CO, United States, (29)University of Washington, Department of Atmospheric Sciences, Seattle, WA, United States
Abstract:
Biomass burning emissions from both wildfires and agricultural burning include a suite of highly reactive volatile organic compounds (VOCs). Oxidation of biomass burning VOCs occurs by reactions with oxidants OH, O3, and NO3. At night or in opaque plumes smoke is oxidized mainly by O3 and NO3. In contrast, during the daytime when light penetrates the plumes smoke is oxidized mainly by O3 and OH. This work focuses on the transition between daytime and nighttime oxidation which has been historically understudied. We present wildfire smoke observations made during FIREX-AQ (Fire Influence on Regional to Global Environments and Air Quality) aboard the NASA DC-8 and NOAA Twin Otter aircrafts. FIREX-AQ was a large campaign involving multiple aircraft, ground, satellite, and mobile platforms that took place in the United States in the summer of 2019 to study both wildfire and agricultural burning emissions and chemistry. We analyzed smoke intercepted during mid-day, sunset, and nighttime that resembled this transition region. We use positive matrix factorization (PMF) of I- chemical ionization mass spectrometer datasets from both aircraft as well as an explicit chemical model analysis constrained by aircraft observations to understand the chemical evolution from emission through the night. We find a four factor PMF solution differentiates fresh emissions from secondary and aged smoke. These factors identified several characteristics of plume chemistry, including diel variation and differences between the plume center and plume edges that correlate with differences in light exposure controlled by absorption and scattering by aerosols. We use our box model to understand the distribution of VOC loss by each oxidant as smoke in the transition regime ages overnight. Phenolics are mainly oxidized by O3 with roughly equal oxidation by OH and NO3 while furans and furfurals are mainly oxidized by O3 or OH depending on the NOx and O3 conditions of the smoke.
