Absorptivity of brown carbon in fresh and photo-chemically aged biomass-burning emissions 1Center for Atmospheric Particle Studies, Carnegie Mellon University, Pittsburgh PA, USA
09 Aug 2013
2Chemical, Biochemical, and Environmental Engineering, University of Maryland Baltimore County, Baltimore MD, USA
3Droplet Measurement Technologies, Boulder CO, USA
4Centre for Atmospheric Science, University of Manchester, Manchester, UK
Received: 23 April 2013 – Published in Atmos. Chem. Phys. Discuss.: 02 May 2013 Abstract. Experiments were conducted to investigate light absorption of organic
aerosol (OA) in fresh and photo-chemically aged biomass-burning emissions.
The experiments considered residential hardwood fuel (oak) and fuels
commonly consumed in wild-land and prescribed fires in the United States
(pocosin pine and gallberry). Photo-chemical aging was performed in an
environmental chamber. We constrained the effective light-absorption
properties of the OA using conservative limiting assumptions, and found that
both primary organic aerosol (POA) in the fresh emissions and secondary
organic aerosol (SOA) produced by photo-chemical aging contain brown carbon,
and absorb light to a significant extent. This work presents the first
direct evidence that SOA produced in aged biomass-burning emissions is
absorptive. For the investigated fuels, SOA is less absorptive than POA in
the long visible, but exhibits stronger wavelength-dependence and is more
absorptive in the short visible and near-UV. Light absorption by SOA in
biomass-burning emissions might be an important contributor to the global
radiative forcing budget.
Revised: 02 July 2013 – Accepted: 03 July 2013 – Published: 09 August 2013
Citation: Saleh, R., Hennigan, C. J., McMeeking, G. R., Chuang, W. K., Robinson, E. S., Coe, H., Donahue, N. M., and Robinson, A. L.: Absorptivity of brown carbon in fresh and photo-chemically aged biomass-burning emissions, Atmos. Chem. Phys., 13, 7683-7693, doi:10.5194/acp-13-7683-2013, 2013.