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Emissions of Reactive Nitrogen From Western U.S. Wildfires During Summer 2018
Author(s) -
Lindaas Jakob,
Pollack Ilana B.,
Garofalo Lauren A.,
Pothier Matson A.,
Farmer Delphine K.,
Kreidenweis Sonia M.,
Campos Teresa L.,
Flocke Frank,
Weinheimer Andrew J.,
Montzka Denise D.,
Tyndall Geoffrey S.,
Palm Brett B.,
Peng Qiaoyun,
Thornton Joel A.,
Permar Wade,
Wielgasz Catherine,
Hu Lu,
Ottmar Roger D.,
Restaino Joseph C.,
Hudak Andrew T.,
Ku ITing,
Zhou Yong,
Sive Barkley C.,
Sullivan Amy,
Collett Jeffrey L.,
Fischer Emily V.
Publication year - 2021
Publication title -
journal of geophysical research: atmospheres
Language(s) - English
Resource type - Journals
eISSN - 2169-8996
pISSN - 2169-897X
DOI - 10.1029/2020jd032657
Subject(s) - reactive nitrogen , nitrogen , ozone , mixing ratio , atmospheric sciences , volatilisation , combustion , aerosol , smoke , environmental science , atmospheric chemistry , nitrogen oxides , environmental chemistry , chemistry , physics , organic chemistry , engineering , waste management
Reactive nitrogen ( N r ) within smoke plumes plays important roles in the production of ozone, the formation of secondary aerosols, and deposition of fixed N to ecosystems. The Western Wildfire Experiment for Cloud Chemistry, Aerosol Absorption, and Nitrogen (WE‐CAN) field campaign sampled smoke from 23 wildfires throughout the western U.S. during summer 2018 using the NSF/NCAR C‐130 research aircraft. We empirically estimate N r normalized excess mixing ratios and emission factors from fires sampled within 80 min of estimated emission and explore variability in the dominant forms of N r between these fires. We find that reduced N compounds comprise a majority (39%–80%; median = 66%) of total measured reactive nitrogen ( ΣN r ) emissions. The smoke plumes sampled during WE‐CAN feature rapid chemical transformations after emission. As a result, within minutes after emission total measured oxidized nitrogen ( Σ NO y ) and measured total Σ NH x (NH 3 + p NH 4 ) are more robustly correlated with modified combustion efficiency (MCE) than NO x and NH 3 by themselves. The ratio of ΣNH x /ΣNO y displays a negative relationship with MCE, consistent with previous studies. A positive relationship with total measured ΣN r suggests that both burn conditions and fuel N content/volatilization differences contribute to the observed variability in the distribution of reduced and oxidized N r . Additionally, we compare our in situ field estimates of N r EFs to previous lab and field studies. For similar fuel types, we find Σ NH x EFs are of the same magnitude or larger than lab‐based NH 3 EF estimates, and Σ NO y EFs are smaller than lab NO x EFs.