title: Enhanced light absorption by mixed source black and brown carbon particles in UK winter.
abstract: 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.
authors.affiliation: Earth and Environmental Sciences Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA.|Cooperative Institute for Research in the Environmental Sciences and Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309, USA.
authors.forename: Shang
authors.initials: S
authors.lastname: Liu
authors.affiliation: Earth and Environmental Sciences Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA.
authors.forename: Allison C
authors.initials: AC
authors.lastname: Aiken
authors.affiliation: Earth and Environmental Sciences Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA.|Department of Civil and Environmental Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, USA.
authors.forename: Kyle
authors.initials: K
authors.lastname: Gorkowski
authors.affiliation: Earth and Environmental Sciences Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA.
authors.forename: Manvendra K
authors.initials: MK
authors.lastname: Dubey
authors.affiliation: Department of Civil and Environmental Engineering, University of California, Davis, California 95616, USA.
authors.forename: Christopher D
authors.initials: CD
authors.lastname: Cappa
authors.affiliation: Aerodyne Research, Inc. Billerica, Massachusetts 01821, USA.
authors.forename: Leah R
authors.initials: LR
authors.lastname: Williams
authors.affiliation: Aerodyne Research, Inc. Billerica, Massachusetts 01821, USA.
authors.forename: Scott C
authors.initials: SC
authors.lastname: Herndon
authors.affiliation: Aerodyne Research, Inc. Billerica, Massachusetts 01821, USA.
authors.forename: Paola
authors.initials: P
authors.lastname: Massoli
authors.affiliation: Aerodyne Research, Inc. Billerica, Massachusetts 01821, USA.
authors.forename: Edward C
authors.initials: EC
authors.lastname: Fortner
authors.affiliation: Aerodyne Research, Inc. Billerica, Massachusetts 01821, USA.|Department of Chemical Engineering, University of Texas at Austin, Austin, Texas 78712, USA.
authors.forename: Puneet S
authors.initials: PS
authors.lastname: Chhabra
authors.affiliation: Aerodyne Research, Inc. Billerica, Massachusetts 01821, USA.
authors.forename: William A
authors.initials: WA
authors.lastname: Brooks
authors.affiliation: Aerodyne Research, Inc. Billerica, Massachusetts 01821, USA.|Department of Chemistry, Boston College, Boston, Massachusetts 02467, USA.
authors.forename: Timothy B
authors.initials: TB
authors.lastname: Onasch
authors.affiliation: Aerodyne Research, Inc. Billerica, Massachusetts 01821, USA.
authors.forename: John T
authors.initials: JT
authors.lastname: Jayne
authors.affiliation: Aerodyne Research, Inc. Billerica, Massachusetts 01821, USA.
authors.forename: Douglas R
authors.initials: DR
authors.lastname: Worsnop
authors.affiliation: Physics Department and Atmospheric Sciences Program, Michigan Technological University, Houghton, Michigan 49931, USA.
authors.forename: Swarup
authors.initials: S
authors.lastname: China
authors.affiliation: Physics Department and Atmospheric Sciences Program, Michigan Technological University, Houghton, Michigan 49931, USA.
authors.forename: Noopur
authors.initials: N
authors.lastname: Sharma
authors.affiliation: Physics Department and Atmospheric Sciences Program, Michigan Technological University, Houghton, Michigan 49931, USA.
authors.forename: Claudio
authors.identifier: http://orcid.org/0000-0002-2398-0721
authors.initials: C
authors.lastname: Mazzoleni
authors.affiliation: School of Chemical and Biomolecular Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332, USA.
authors.forename: Lu
authors.initials: L
authors.lastname: Xu
authors.affiliation: School of Chemical and Biomolecular Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332, USA.|School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, Georgia 30332, USA.
authors.forename: Nga L
authors.initials: NL
authors.lastname: Ng
authors.affiliation: School of Earth, Atmospheric and Environmental Science, University of Manchester, Manchester M13 9PL, UK.
authors.forename: Dantong
authors.initials: D
authors.lastname: Liu
authors.affiliation: School of Earth, Atmospheric and Environmental Science, University of Manchester, Manchester M13 9PL, UK.|National Centre for Atmospheric Science, University of Manchester, Manchester M13 9PL, UK.
authors.forename: James D
authors.initials: JD
authors.lastname: Allan
authors.affiliation: Wolfson Atmospheric Chemistry Laboratory and National Centre for Atmospheric Science, University of York, York YO10 5DD, UK.
authors.forename: James D
authors.initials: JD
authors.lastname: Lee
authors.affiliation: National Centre for Atmospheric Science, Department of Chemistry, University of Leicester, Leicester LE1 7RH, UK.
authors.forename: Zoë L
authors.initials: ZL
authors.lastname: Fleming
authors.affiliation: Department of Atmospheric Sciences, University of Washington, Seattle, Washington 98195, USA.|Institute for Meteorology and Climate Research, Karlsruhe Institute of Technology, Eggenstein-Leopoldshafen 76344, Germany.
authors.forename: Claudia
authors.identifier: http://orcid.org/0000-0002-3291-9295
authors.initials: C
authors.lastname: Mohr
authors.affiliation: Laboratory of Atmospheric Chemistry, Paul Scherrer Institute, Villigen 5232, Switzerland.|Lucerne School of Engineering and Architecture, Bioenergy Research, Lucerne University of Applied Sciences and Arts, Horw 6048, Switzerland.
authors.forename: Peter
authors.initials: P
authors.lastname: Zotter
authors.affiliation: Department of Chemistry and Biochemistry and Oeschger Centre for Climate Change Research, University of Bern, Bern 3012, Switzerland.
authors.forename: Sönke
authors.initials: S
authors.lastname: Szidat
authors.affiliation: Laboratory of Atmospheric Chemistry, Paul Scherrer Institute, Villigen 5232, Switzerland.
authors.forename: André S H
authors.initials: ASH
authors.lastname: Prévôt