Formaldehyde evolution in US wildfire plumes during the Fire Influence on Regional to Global Environments and Air Quality experiment (FIREX-AQ)

Fried, Alan; Weibring, Petter; Richter, Dirk; Selimovic, Vanessa

Citeable URL: https://scholar.colorado.edu/concern/articles/qf85nc75r

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 Fire Influence on Regional to Global Environments and Air Quality experiment (FIREX-AQ) field campaign. In 9 of the 12 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) seems to control 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. The production and loss rates of dilution-normalized HCHO seem to decrease with plume age. 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 and to VOC emissions.

Full List of Authors

Jin Liao^1,2, Glenn M. Wolfe¹, Reem A. Hannun^1,3, Jason M. St. Clair^1,3, Thomas F. Hanisco¹, Jessica B. Gilman⁴, Aaron Lamplugh^4,5, 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. Ryerson^4,a, Jeff Peischl^4,5, Ilann Bourgeois^4,5, Carsten Warneke⁴, Matthew M. Coggon^4,5, Georgios I. Gkatzelis^4,5,b, Kanako Sekimoto¹¹, Alan Fried¹², Dirk Richter¹², Petter Weibring¹², Eric C. Apel⁹, Rebecca S. Hornbrook⁹, Steven S. Brown⁴, Caroline C. Womack^4,5, Michael A. Robinson^4,5, Rebecca A. Washenfelder⁴, Patrick R. Veres⁴, and J. Andrew Neuman^4,5
- ¹Atmospheric Chemistry and Dynamics Laboratory, NASA Goddard Space Flight Center, Greenbelt, MD, USA
- ²Goddard Earth Science Technology and Research (GESTAR) II, University of Maryland Baltimore County, Baltimore, 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, Tallahassee, FL, USA
- ¹¹Yokohama City University, Yokohama, Japan
- ¹²Institute of Arctic and Alpine Research (INSTAAR), University of Colorado, Boulder, CO, USA
- ^anow at: Scientific Aviation, Boulder, CO, USA
- ^bnow at: Forschungszentrum Jülich GmbH, Jülich, Nordrhein-Westfalen, Germany

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