Journal cover Journal topic
Atmospheric Chemistry and Physics An interactive open-access journal of the European Geosciences Union
Atmos. Chem. Phys., 14, 13755-13771, 2014
https://doi.org/10.5194/acp-14-13755-2014
© Author(s) 2014. This work is distributed under
the Creative Commons Attribution 3.0 License.
Research article
22 Dec 2014
Size-dependent wet removal of black carbon in Canadian biomass burning plumes
J. W. Taylor1, J. D. Allan1,2, G. Allen1, H. Coe1, P. I. Williams1,2, M. J. Flynn1, M. Le Breton1, J. B. A. Muller1, C. J. Percival1, D. Oram3, G. Forster3, J. D. Lee4, A. R. Rickard5,*, M. Parrington6,**, and P. I. Palmer6 1Centre for Atmospheric Science, School of Earth, Atmospheric and Environmental Sciences, University of Manchester, Manchester, UK
2National Centre for Atmospheric Science, University of Manchester, Manchester, UK
3National Centre for Atmospheric Science (NCAS), School of Environmental Sciences, University of East Anglia, Norwich, UK
4National Centre for Atmospheric Science (NCAS), Department of Chemistry, University of York, York, UK
5National Centre for Atmospheric Science (NCAS), School of Chemistry, University of Leeds, Leeds, UK
6School of GeoSciences, University of Edinburgh, Edinburgh, UK
*now at: the National Centre for Atmospheric Science (NCAS), Department of Chemistry, University of York, York, UK
**now at: European Centre for Medium-Range Weather Forecasts, Shinfield Park, Reading, RG2 9AX, UK
Abstract. Wet deposition is the dominant mechanism for removing black carbon (BC) from the atmosphere and is key in determining its atmospheric lifetime, vertical gradient and global transport. Despite the importance of BC in the climate system, especially in terms of its ability to modulate the radiative energy budget, there are few quantitative case studies of wet removal in ambient environments. We present a case study of BC wet removal by examining aerosol size distributions and BC coating properties sampled in three Canadian boreal biomass burning plumes, one of which passed through a precipitating cloud. This depleted the majority of the plume's BC mass, and the largest and most coated BC-containing particles were found to be preferentially removed, suggesting that nucleation scavenging was likely the dominant mechanism. Calculated single-scattering albedo (SSA) showed little variation, as a large number of non-BC particles were also present in the precipitation-affected plume. The remaining BC cores were smaller than those observed in previous studies of BC in post-precipitation outflow over Asia, possibly due to the thick coating by hydrophilic compounds associated with the Canadian biomass burning particles. This study provides measurements of BC size, mixing state and removal efficiency to constrain model parameterisations of BC wet removal in biomass burning regions, which will help to reduce uncertainty in radiative forcing calculations.

Citation: Taylor, J. W., Allan, J. D., Allen, G., Coe, H., Williams, P. I., Flynn, M. J., Le Breton, M., Muller, J. B. A., Percival, C. J., Oram, D., Forster, G., Lee, J. D., Rickard, A. R., Parrington, M., and Palmer, P. I.: Size-dependent wet removal of black carbon in Canadian biomass burning plumes, Atmos. Chem. Phys., 14, 13755-13771, https://doi.org/10.5194/acp-14-13755-2014, 2014.
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We present a case study of BC wet removal by examining aerosol properties in three biomass burning plumes, one of which passed through a precipitating cloud. Nucleation scavenging preferentially removed the largest and most coated BC-containing particles. Calculated single-scattering albedo (SSA) showed little variation, as a large number of non-BC particles were also present in the precipitation-affected plume.
We present a case study of BC wet removal by examining aerosol properties in three biomass...
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