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

Authors :
J. Liao
G. M. Wolfe
R. A. Hannun
J. M. St. Clair
T. F. Hanisco
J. B. Gilman
A. Lamplugh
V. Selimovic
G. S. Diskin
J. B. Nowak
H. S. Halliday
J. P. DiGangi
S. R. Hall
K. Ullmann
C. D. Holmes
C. H. Fite
A. Agastra
T. B. Ryerson
J. Peischl
I. Bourgeois
C. Warneke
M. M. Coggon
G. I. Gkatzelis
K. Sekimoto
A. Fried
D. Richter
P. Weibring
E. C. Apel
R. S. Hornbrook
S. S. Brown
C. C. Womack
M. A. Robinson
R. A. Washenfelder
P. R. Veres
J. A. Neuman
Source :
Atmospheric Chemistry and Physics, Vol 21, Pp 18319-18331 (2021)
Publication Year :
2021
Publisher :
Copernicus Publications, 2021.

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.

Subjects

Subjects :
Physics
QC1-999
Chemistry
QD1-999

Details

Language :
English
ISSN :
16807316 and 16807324
Volume :
21
Database :
Directory of Open Access Journals
Journal :
Atmospheric Chemistry and Physics
Publication Type :
Academic Journal
Accession number :
edsdoj.f0100f93a68040c580d00c68c21934e1
Document Type :
article
Full Text :
https://doi.org/10.5194/acp-21-18319-2021