Biomass burning emits vapors and aerosols into the atmosphere that can rapidly evolve as smoke plumes travel downwind and dilute, affecting climate- and health-relevant properties of the smoke. To date, theory has been unable to explain observed variability in smoke evolution. Here, we use observational data from the Biomass Burning Observation Project (BBOP) field campaign and show that initial smoke organic aerosol mass concentrations can help predict changes in smoke aerosol aging markers, number concentration, and number mean diameter between 40-262 nm. Because initial field measurements of plumes are generally > 10 min downwind, smaller plumes will have already undergone substantial dilution relative to larger plumes and have lower concentrations of smoke species at these observations closest to the fire. The extent to which dilution has occurred prior to the first observation is not a directly measurable quantity. We show that initial observed plume concentrations can serve as a rough indicator of the extent of dilution prior to the first measurement, which impacts photochemistry, aerosol evaporation, and coagulation. Cores of plumes have higher concentrations than edges. By segregating the observed plumes into cores and edges, we find evidence that particle aging, evaporation, and coagulation occurred before the first measurement. We further find that on the plume edges, the organic aerosol is more oxygenated, while a marker for primary biomass burning aerosol emissions has decreased in relative abundance compared to the plume cores. Finally, we attempt to decouple the roles of the initial concentrations and physical age since emission by performing multivariate linear regression of various aerosol properties (composition, size) on these two factors.


Civil, Architectural and Environmental Engineering


This research has been supported by the National Oceanic and Atmospheric Administration Climate Program Office (grant nos. NA17OAR4310001, NA17OAR4310003, and NA17OAR4310010), the National Science Foundation (grant nos. AGS-1559607 and AGS-1950327), and the US Department of Energy Office of Science (grant nos. DE-SC0019000, DE-SC0012704, DE-SC0014287, and DE-SC0020259).

International Standard Serial Number (ISSN)

1680-7324; 1680-7316

Document Type

Article - Journal

Document Version

Final Version

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© 2021 The Authors, All rights reserved.

Creative Commons Licensing

Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 License.

Publication Date

05 May 2021