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Enhanced light absorption by mixed source black and brown carbon particles in UK winter

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posted on 02.10.2019, 14:40 by S Liu, AC Aiken, K Gorkowski, MK Dubey, CD Cappa, LR Williams, SC Herndon, P Massoli, EC Fortner, PS Chhabra, WA Brooks, TB Onasch, JT Jayne, DR Worsnop, S China, N Sharma, C Mazzoleni, L Xu, NL Ng, D Liu, JD Allan, JD Lee, ZL Fleming, C Mohr, P Zotter, S Szidat, ASH Prévôt
Black carbon (BC) and light-absorbing organic carbon (brown carbon, BrC) play key roles in warming the atmosphere, but the magnitude of their effects remains highly uncertain. Theoretical modelling and laboratory experiments demonstrate that coatings on BC can enhance BC’s light absorption, therefore many climate models simply assume enhanced BC absorption by a factor of ∼1.5. However, recent field observations show negligible absorption enhancement, implying models may overestimate BC’s warming. Here we report direct evidence of substantial field-measured BC absorption enhancement, with the magnitude strongly depending on BC coating amount. Increases in BC coating result from a combination of changing sources and photochemical aging processes. When the influence of BrC is accounted for, observationally constrained model calculations of the BC absorption enhancement can be reconciled with the observations. We conclude that the influence of coatings on BC absorption should be treated as a source and regionally specific parameter in climate models.


This research was supported by the US Department of Energy Office of Science Atmospheric System Research (ASR) program grant F265 to LANL (PI M.K.D.). A.C.A. acknowledges Director’s postdoctoral funding from LANL’s LDRD program. C.D.C. was supported by US DOE Award No. DE-SC0008937. The Aerodyne and Georgia Institute of Technology participants were supported by US DOE Award No. DE-SC0006002. The electron microscopy analysis was supported by US DOE grant No. DE-SC0010019. The authors are grateful to the UK Met Office for the use of their NAME dispersion model. We would like to thank David Green of Kings’ College London for his assistance in setting up the Detling site. Detling site logistics were supported by the NERC ClearfLo project (Grant ref. NE/H00324X/1).



Nature Communications, 2015, volume 6, Article number: 8435

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/Organisation/COLLEGE OF SCIENCE AND ENGINEERING/Department of Chemistry


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