Quantification of black carbon mixing state from traffic: Implications for aerosol optical properties
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Published Version
Supplementary File 1
Date
2016-04-14
Authors
Willis, Megan D.
Healy, Robert M.
Riemer, Nicole
West, Matthew
Wang, Jon M.
Jeong, Cheol-Heon
Wenger, John C.
Evans, Greg J.
Abbatt, Jonathan P. D.
Lee, Alex K. Y.
Journal Title
Journal ISSN
Volume Title
Publisher
European Geosciences Union
Published Version
Abstract
The climatic impacts of black carbon (BC) aerosol, an important absorber of solar radiation in the atmosphere, remain poorly constrained and are intimately related to its particle-scale physical and chemical properties. Using particle-resolved modelling informed by quantitative measurements from a soot-particle aerosol mass spectrometer, we confirm that the mixing state (the distribution of co-emitted aerosol amongst fresh BC-containing particles) at the time of emission significantly affects BC-aerosol optical properties even after a day of atmospheric processing. Both single particle and ensemble aerosol mass spectrometry observations indicate that BC near the point of emission co-exists with hydrocarbon-like organic aerosol (HOA) in two distinct particle types: HOA-rich and BC-rich particles. The average mass fraction of black carbon in HOA-rich and BC-rich particle classes was < 0.1 and 0.8, respectively. Notably, approximately 90 % of BC mass resides in BC-rich particles. This new measurement capability provides quantitative insight into the physical and chemical nature of BC-containing particles and is used to drive a particle-resolved aerosol box model. Significant differences in calculated single scattering albedo (an increase of 0.1) arise from accurate treatment of initial particle mixing state as compared to the assumption of uniform aerosol composition at the point of BC injection into the atmosphere.
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Keywords
Black carbon mixing , Aerosol optical properties
Citation
Willis, M. D., Healy, R. M., Riemer, N., West, M., Wang, J. M., Jeong, C. H., Wenger, J. C., Evans, G. J., Abbatt, J. P. D. and Lee, A. K. Y. (2016) 'Quantification of black carbon mixing state from traffic: implications for aerosol optical properties',Atmospheric Chemistry and Physics, 16, pp.4693-4706. doi: 10.5194/acp-16-4693-2016