Complexity in the Evolution, Composition, and Spectroscopy of Brown Carbon in Aircraft Measurements of Wildfire Plumes
Abstract
Biomass burning is a major source of light-absorbing organic aerosol (brown carbon), but its composition, chemical evolution, and lifetime are not well known. We measured water-soluble brown carbon absorption from 310 to 500 nm on the National Oceanic and Atmospheric Administration Twin Otter aircraft during flights downwind of western United States wildfires in summer 2019. The sampling strategy was near-Lagrangian and the plume ages spanned 0–5 hr. Trends in brown carbon mass absorption coefficient with plume age varied between flights, and did not show an exponential decay over these short time scales. The measured absorption spectra were smoothly varying, without identifiable contributions from individual chromophores with structured absorption. Using aerosol tracer ions and reference absorption spectra, the calculated contribution of 4-nitrocatechol to total absorption was <22 ± 9% and <11 ± 5%, although spectral fitting showed that it may be as low as <1.1% and <0.6% at 365 and 405 nm, respectively.
Additional Information
© 2022 American Geophysical Union. Issue Online: 05 May 2022; Version of Record online: 05 May 2022; Accepted manuscript online: 11 April 2022; Manuscript accepted: 05 April 2022; Manuscript received: 30 March 2022. We thank Carsten Warneke, Joshua Schwarz, James Crawford, and Jack Dibb for organizing the FIREX-AQ field campaign. We thank the NOAA Aircraft Operations Center for support during the field mission. R. A. Washenfelder thanks Rodney Weber and Linghan Zeng for information about the solubility of BrC in biomass burning plumes, and Amy Sullivan and Nick Wagner for helpful discussions. This project was supported by the NOAA Atmospheric Chemistry, Carbon, and Climate Program (AC4). Z. C. J. Decker was supported by a graduate research award at the University of Colorado CIRES. L. Azzarello was supported by a Mitacs Globalink Research Internship and an NSERC Discovery Grant. The AMS calibration work was supported by NASA grant 17-ACLS17-0014. Data Availability Statement: The aircraft data used in the study are publicly available at https://www-air.larc.nasa.gov/missions/firex-aq/.Attached Files
Published - 2022GL098951.pdf
Accepted Version - 2022GL098951-acc.pdf
Supplemental Material - 2022gl098951-sup-0001-supporting_information_si-s01.pdf
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Additional details
- Alternative title
- Brown carbon from wildfire plumes
- Eprint ID
- 114307
- Resolver ID
- CaltechAUTHORS:20220414-26504000
- National Oceanic and Atmospheric Administration (NOAA)
- University of Colorado
- MITACS
- Natural Sciences and Engineering Research Council of Canada (NSERC)
- 17-ACLS17-0014
- NASA
- Created
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2022-04-18Created from EPrint's datestamp field
- Updated
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2023-10-06Created from EPrint's last_modified field