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Biomass burning dominates brown carbon absorption in the rural southeastern United States
Author(s) -
Washenfelder R. A.,
Attwood A. R.,
Brock C. A.,
Guo H.,
Xu L.,
Weber R. J.,
Ng N. L.,
Allen H. M.,
Ayres B. R.,
Baumann K.,
Cohen R. C.,
Draper D. C.,
Duffey K. C.,
Edgerton E.,
Fry J. L.,
Hu W. W.,
Jimenez J. L.,
Palm B. B.,
Romer P.,
Stone E. A.,
Wooldridge P. J.,
Brown S. S.
Publication year - 2015
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1002/2014gl062444
Subject(s) - aerosol , single scattering albedo , extinction (optical mineralogy) , environmental science , absorption (acoustics) , atmospheric sciences , mineralogy , chemistry , meteorology , physics , optics
Abstract Brown carbon aerosol consists of light‐absorbing organic particulate matter with wavelength‐dependent absorption. Aerosol optical extinction, absorption, size distributions, and chemical composition were measured in rural Alabama during summer 2013. The field site was well located to examine sources of brown carbon aerosol, with influence by high biogenic organic aerosol concentrations, pollution from two nearby cities, and biomass burning aerosol. We report the optical closure between measured dry aerosol extinction at 365 nm and calculated extinction from composition and size distribution, showing agreement within experiment uncertainties. We find that aerosol optical extinction is dominated by scattering, with single‐scattering albedo values of 0.94 ± 0.02. Black carbon aerosol accounts for 91 ± 9% of the total carbonaceous aerosol absorption at 365 nm, while organic aerosol accounts for 9 ± 9%. The majority of brown carbon aerosol mass is associated with biomass burning, with smaller contributions from biogenically derived secondary organic aerosol.