31 May 2021

31 May 2021

Review status: a revised version of this preprint is currently under review for the journal ACP.

Formaldehyde evolution in U.S. wildfire plumes during FIREX-AQ

Jin Liao1,2, Glenn M. Wolfe1, Reem A. Hannun1,3, Jason M. St. Clair1,3, Thomas F. Hanisco1, Jessica B. Gilman4, Aaron Lamplugh4,5, Vanessa Selimovic6, Glenn S. Diskin7, John B. Nowak7, Hannah S. Halliday8, Joshua P. DiGangi7, Samuel R. Hall9, Kirk Ullmann9, Christopher D. Holmes10, Charles H. Fite10, Anxhelo Agastra10, Thomas B. Ryerson4,a, Jeff Peischl4,5, Ilann Bourgeois4,5, Carsten Warneke4, Matthew M. Coggon4,5, Georgios I. Gkatzelis4,5,b, Kanako Sekimoto11, Alan Fried12, Dirk Richter12, Petter Weibring12, Eric C. Apel9, Rebecca S. Hornbrook9, Steven S. Brown4, Caroline C. Womack4,5, Michael A. Robinson4,5, Rebecca A. Washenfelder4, Patrick R. Veres4, and J. Andrew Neuman4,5 Jin Liao et al.
  • 1Atmospheric Chemistry and Dynamics Laboratory, NASA Goddard Space Flight Center, Greenbelt, MD, USA
  • 2Universities Space Research Association, Columbia, MD, USA
  • 3Joint Center for Earth Systems Technology, University of Maryland Baltimore County, Baltimore, MD, USA
  • 4NOAA Chemical Science Laboratory (CSL), Boulder, CO, USA
  • 5Cooperative Institute for Research in Environmental Science (CIRES), University of Colorado, Boulder, CO, USA
  • 6Department of Chemistry, University of Montana, Missoula, MT, USA
  • 7NASA Langley Research Center, Hampton, VA, USA
  • 8Environmental Protection Agency, Durham, NC, USA
  • 9Atmospheric Chemistry Observations & Modeling Laboratory, National Center for Atmospheric Research, Boulder, CO, USA
  • 10Earth, Ocean and Atmospheric Science, Florida State University, FL, USA
  • 11Yokohama City University, Japan
  • 12Institute of Arctic and Alpine Research (INSTAAR), University of Colorado, Colorado, USA
  • anow at: Scientific Aviation, Boulder, Colorado, USA
  • bnow at: Forschungszentrum Jülich GmbH, Julich, Nordrhein-Westfalen, DE, Germany

Abstract. Formaldehyde (HCHO) is one of the most abundant non-methane volatile organic compounds (VOCs) emitted by fires. HCHO also undergoes chemical production and loss as a fire plume ages, and it can be an important oxidant precursor. In this study, we disentangle the processes controlling HCHO by examining its evolution in wildfire plumes sampled by the NASA DC-8 during the FIREX-AQ field campaign. In nine of the twelve analyzed plumes, dilution-normalized HCHO increases with physical age (range 1–6 h). The balance of HCHO loss (mainly via photolysis) and production (via OH-initiated VOC oxidation) controls the sign and magnitude of this trend. Plume-average OH concentrations, calculated from VOC decays, range from −0.5 (±0.5) × 106 to 5.3 (±0.7) × 106 cm−3. Plume-to-plume variability in dilution-normalized secondary HCHO production correlates with OH abundance rather than normalized OH reactivity, suggesting that OH is the main driver of fire-to-fire variability in HCHO secondary production. Analysis suggests an effective HCHO yield of 0.33 (±0.05) per VOC molecule oxidized for the 12 wildfire plumes. This finding can help connect space-based HCHO observations to the oxidizing capacity of the atmosphere.

Jin Liao et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on acp-2021-389', Anonymous Referee #1, 25 Jun 2021
  • RC2: 'Comment on acp-2021-389', Anonymous Referee #2, 02 Jul 2021

Jin Liao et al.


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Short summary
Formaldehyde is an important oxidant precursor and affects the formation of O3 and other secondary pollutants in wildfire plumes. We disentangle the processes controlling HCHO evolution from a variety of wildfire plumes sampled by NASA DC-8 during FIREX-AQ field campaign. We find that OH abundance rather than normalized OH reactivity is the main driver of fire-to-fire variability in HCHO secondary production and estimate an effective HCHO yield per VOC molecule oxidized in wildfire plumes.