In:
Atmospheric Chemistry and Physics, Copernicus GmbH, Vol. 21, No. 24 ( 2021-12-17), p. 18319-18331
Kurzfassung:
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.
Materialart:
Online-Ressource
ISSN:
1680-7324
DOI:
10.5194/acp-21-18319-2021
DOI:
10.5194/acp-21-18319-2021-supplement
Sprache:
Englisch
Verlag:
Copernicus GmbH
Publikationsdatum:
2021
ZDB Id:
2092549-9
ZDB Id:
2069847-1
