title: Enhanced Volatile Organic Compounds emissions and organic aerosol mass increase the oligomer content of atmospheric aerosols.
abstract: Secondary organic aerosol (SOA) accounts for a dominant fraction of the submicron atmospheric particle mass, but knowledge of the formation, composition and climate effects of SOA is incomplete and limits our understanding of overall aerosol effects in the atmosphere. Organic oligomers were discovered as dominant components in SOA over a decade ago in laboratory experiments and have since been proposed to play a dominant role in many aerosol processes. However, it remains unclear whether oligomers are relevant under ambient atmospheric conditions because they are often not clearly observed in field samples. Here we resolve this long-standing discrepancy by showing that elevated SOA mass is one of the key drivers of oligomer formation in the ambient atmosphere and laboratory experiments. We show for the first time that a specific organic compound class in aerosols, oligomers, is strongly correlated with cloud condensation nuclei (CCN) activities of SOA particles. These findings might have important implications for future climate scenarios where increased temperatures cause higher biogenic volatile organic compound (VOC) emissions, which in turn lead to higher SOA mass formation and significant changes in SOA composition. Such processes would need to be considered in climate models for a realistic representation of future aerosol-climate-biosphere feedbacks.
authors.affiliation: Department of Chemistry, University of Cambridge, Cambridge, CB2 1EW, UK.|Department of Chemistry and Environmental Research Institute, University College Cork, Cork, Ireland.
authors.forename: Ivan
authors.initials: I
authors.lastname: Kourtchev
authors.affiliation: Department of Chemistry, University of Cambridge, Cambridge, CB2 1EW, UK.
authors.forename: Chiara
authors.initials: C
authors.lastname: Giorio
authors.affiliation: Department of Physics, University of Helsinki, P.O. Box 64, 00014, University of Helsinki, Helsinki, Finland.
authors.forename: Antti
authors.initials: A
authors.lastname: Manninen
authors.affiliation: Department of Chemistry and Environmental Research Institute, University College Cork, Cork, Ireland.
authors.forename: Eoin
authors.initials: E
authors.lastname: Wilson
authors.affiliation: Department of Chemistry, University of Cambridge, Cambridge, CB2 1EW, UK.
authors.forename: Brendan
authors.initials: B
authors.lastname: Mahon
authors.affiliation: Department of Physics, University of Helsinki, P.O. Box 64, 00014, University of Helsinki, Helsinki, Finland.|Department of Forest Sciences, P.O. Box 27, FI-00014 University of Helsinki, Finland.|Hyytiälä Forestry Field Station, Hyytiäläntie 124, Korkeakoski, 35500, Finland.
authors.forename: Juho
authors.initials: J
authors.lastname: Aalto
authors.affiliation: Department of Physics, University of Helsinki, P.O. Box 64, 00014, University of Helsinki, Helsinki, Finland.
authors.forename: Maija
authors.initials: M
authors.lastname: Kajos
authors.affiliation: Department of Chemistry and Environmental Research Institute, University College Cork, Cork, Ireland.|Leibniz Institute for Tropospheric Research (TROPOS), Permoserstr. 15, 04318 Leipzig, Germany.
authors.forename: Dean
authors.initials: D
authors.lastname: Venables
authors.affiliation: Department of Physics, University of Helsinki, P.O. Box 64, 00014, University of Helsinki, Helsinki, Finland.
authors.forename: Taina
authors.initials: T
authors.lastname: Ruuskanen
authors.affiliation: Department of Physics, University of Helsinki, P.O. Box 64, 00014, University of Helsinki, Helsinki, Finland.|Hyytiälä Forestry Field Station, Hyytiäläntie 124, Korkeakoski, 35500, Finland.
authors.forename: Janne
authors.initials: J
authors.lastname: Levula
authors.affiliation: Department of Physics, University of Helsinki, P.O. Box 64, 00014, University of Helsinki, Helsinki, Finland.|Hyytiälä Forestry Field Station, Hyytiäläntie 124, Korkeakoski, 35500, Finland.
authors.forename: Matti
authors.initials: M
authors.lastname: Loponen
authors.affiliation: Department of Chemistry, University of Cambridge, Cambridge, CB2 1EW, UK.
authors.forename: Sarah
authors.initials: S
authors.lastname: Connors
authors.affiliation: Department of Chemistry, University of Cambridge, Cambridge, CB2 1EW, UK.|Centre for Atmospheric Informatics and Emissions Technology, Cranfield University, Cranfield MK43 0AL, UK.
authors.forename: Neil
authors.initials: N
authors.lastname: Harris
authors.affiliation: Institut für Energie- und Klimaforschung (IEK-8), Forschungszentrum Jülich GmbH.
authors.forename: Defeng
authors.initials: D
authors.lastname: Zhao
authors.affiliation: Institut für Energie- und Klimaforschung (IEK-8), Forschungszentrum Jülich GmbH.
authors.forename: Astrid
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authors.affiliation: Institut für Energie- und Klimaforschung (IEK-8), Forschungszentrum Jülich GmbH.
authors.forename: Thomas
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authors.lastname: Mentel
authors.affiliation: Department of Earth and Planetary Sciences and Energy Research, Weizmann Institute, Rehovot 76100, Israel.
authors.forename: Yinon
authors.initials: Y
authors.lastname: Rudich
authors.affiliation: Department of Chemistry, Atmospheric Science, University of Gothenburg, 412 96 Göteborg, Sweden.
authors.forename: Mattias
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authors.lastname: Hallquist
authors.affiliation: LISA, CNRS UMR 7583, Universités Paris-Est-Créteil et Paris-Diderot, Institut Pierre Simon Laplace, 61 Avenue du Général de Gaulle, 94010, Créteil, France.
authors.forename: Jean-Francois
authors.initials: JF
authors.lastname: Doussin
authors.affiliation: Department of Analytical Chemistry, Ghent University, Krijgslaan 281, S12, 9000 Ghent, Belgium.|Department of Pharmaceutical Sciences, University of Antwerp, Universiteitsplein 1, 2610 Antwerp, Belgium.
authors.forename: Willy
authors.initials: W
authors.lastname: Maenhaut
authors.affiliation: Department of Forest Sciences, P.O. Box 27, FI-00014 University of Helsinki, Finland.
authors.forename: Jaana
authors.initials: J
authors.lastname: Bäck
authors.affiliation: Department of Physics, University of Helsinki, P.O. Box 64, 00014, University of Helsinki, Helsinki, Finland.
authors.forename: Tuukka
authors.initials: T
authors.lastname: Petäjä
authors.affiliation: Department of Chemistry and Environmental Research Institute, University College Cork, Cork, Ireland.
authors.forename: John
authors.initials: J
authors.lastname: Wenger
authors.affiliation: Department of Physics, University of Helsinki, P.O. Box 64, 00014, University of Helsinki, Helsinki, Finland.
authors.forename: Markku
authors.initials: M
authors.lastname: Kulmala
authors.affiliation: Department of Chemistry, University of Cambridge, Cambridge, CB2 1EW, UK.
authors.forename: Markus
authors.initials: M
authors.lastname: Kalberer