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- Title
Daytime Oxidized Reactive Nitrogen Partitioning in Western U.S. Wildfire Smoke Plumes.
- Authors
Juncosa Calahorrano, Julieta F.; Lindaas, Jakob; O'Dell, Katelyn; Palm, Brett B.; Peng, Qiaoyun; Flocke, Frank; Pollack, Ilana B.; Garofalo, Lauren A.; Farmer, Delphine K.; Pierce, Jeffrey R.; Collett, Jeffrey L.; Weinheimer, Andrew; Campos, Teresa; Hornbrook, Rebecca S.; Hall, Samuel R.; Ullmann, Kirk; Pothier, Matson A.; Apel, Eric C.; Permar, Wade; Hu, Lu
- Abstract
The Western Wildfire Experiment for Cloud Chemistry, Aerosol Absorption, and Nitrogen (WE‐CAN) deployed the NSF/NCAR C‐130 aircraft in summer 2018 across the western U.S. to sample wildfire smoke during its first days of atmospheric evolution. We present a summary of a subset of reactive oxidized nitrogen species (NOy) in plumes sampled in a pseudo‐Lagrangian fashion. Emissions of nitrogen oxides (NOx = NO + NO2) and nitrous acid (HONO) are rapidly converted to more oxidized forms. Within 4 h, ∼86% of the ΣNOy is in the form of peroxy acyl nitrates (PANs) (∼37%), particulate nitrate (pNO3) (∼27%), and gas‐phase organic nitrates (Org N(g)) (∼23%). The average e‐folding time and distance for NOx are ∼90 min and ∼40 km, respectively. Nearly no enhancements in nitric acid (HNO3) were observed in plumes sampled in a pseudo‐Lagrangian fashion, implying HNO3‐limited ammonium nitrate (NH4NO3) formation, with one notable exception that we highlight as a case study. We also summarize the observed partitioning of NOy in all the smoke samples intercepted during WE‐CAN. In smoke samples intercepted above 3 km above sea level (ASL), the contributions of PANs and pNO3 to ΣNOy increase with altitude. WE‐CAN also sampled smoke from multiple fires mixed with anthropogenic emissions over the California Central Valley. We distinguish samples where anthropogenic NOx emissions appear to lead to an increase in NOx abundances by a factor of four and contribute to additional PAN formation. Key Points: NOx and HONO are rapidly converted to other species. The average e‐folding time (distance) for NOx is ∼90 min (∼40 km)In 4 h, PANs contribute ∼37% of the ΣNOy species in smoke; pNO3 is the second largest (∼27%) contributorIn 4 h, Org N(g) constitute a large portion (∼23%) of the ΣNOy in the plumes sample during WE‐CAN
- Subjects
UNITED States; BIOMASS burning &; the environment; WILDFIRES &; climate; WILDFIRES; SMOKE plumes; NITROGEN &; the environment
- Publication
Journal of Geophysical Research. Atmospheres, 2021, Vol 126, Issue 4, p1
- ISSN
2169-897X
- Publication type
Article
- DOI
10.1029/2020JD033484