Constraining the intensive absorption properties of ambient organic aerosol particles based on pan-European observations

Abstract Organic aerosol particles (OA) can absorb solar radiation with varying efficiencies depending on their chemical composition and physical properties. This light-absorbing fraction of OA, commonly referred to as brown carbon (BrC), is difficult to accurately represent in climate models due to the inherent diversity of its optical properties. This variability arises from differences in emission sources and atmospheric processing, as well as from variations in experimental design and the analytical methods used to quantify BrC absorption. As a result, the climate effect of BrC remains uncertain. Here, we studied the light absorption properties of surface ambient OA using measurements from 17 sites across Europe. Combining multi-wavelength absorption measurements from filter-based photometers with OA mass concentrations and source apportionment derived from ACSM/AMS data, we derive empirical estimates of the OA mass absorption cross section (MAC OA ), its wavelength dependence (AAE OA ), the OA density (⍴ OA ), and the MAC associated with different primary and secondary OA sources. We further develop parameterizations that relate MAC OA , AAE OA and ⍴ OA to the ambient black carbon-to-organic aerosol ratio (eBC/OA) and propose a corresponding parameterization for the imaginary refractive index (k OA ). Given the widespread availability of eBC and OA measurements in global monitoring networks, the framework presented here provides a practical approach for estimating the absorptive properties of surface OA particles under real-world conditions.

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Journal
npj Climate and Atmospheric Science
Published
2026-04-10
DOI
https://doi.org/10.1038/s41612-026-01405-9
Primary Topic
Atmospheric chemistry and aerosols
Type
article
Field-Weighted Citation Impact
0.00

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article

Constraining the intensive absorption properties of ambient organic aerosol particles based on pan-European observations

Hannes Keernik, Stergios Vratolis, Saliou Mbengue, Erik Teinemaa et al.
npj Climate and Atmospheric Science
Atmospheric chemistry and aerosols
article

Constraining the intensive absorption properties of ambient organic aerosol particles based on pan-European observations

Hannes Keernik, Stergios Vratolis, Saliou Mbengue, Erik Teinemaa, Manousos Ioannis Manousakas, Minna Aurela, Maria I. Gini, Hanna E. Manninen, Liine Heikkinen, Karl Espen Yttri, Krista Luoma, J. Ovadnevaite, Iasonas Stavroulas, Marek Maasikmets, Doina Nicoleta Nicolae, Benjamin T. Brem, M. Ehn, Anna Tobler, Olga Zografou, Jarkko V. Niemi, Eleni Liakakou, A. Hyvärinen, Martin Rigler, Jeni Vasilescu, Anna Canals-Angerri, Chunshui Lin, J Garros Rovira, Kimmo Teinilä, Martin Gysel-Beer, Joel de Brito, Harald Flentje, Nikos Mihalopoulos, Noemí Pérez, Nicolas Marchand, X. Querol, Marco Pandolfi, Veronique Riffault, Sujai Banerji, Christoph Hueglin, Tuukka Petäjä, Gang I. Chen, Matic Ivančič, María Cruz Minguillón, Stephen M. Platt, Jaroslav Schwarz, Radek Lhotka, Roy Harrison, Konstantinos Granakis, Olivier Favez, Kaspar R. Daellenbach, Asta Gregorič, Benjamin Chazeau, André S. H. Prévôt, John Backman, Griša Močnik, Matteo Rinaldi, Jean-Eudes Petit, Marta Via, Jesús Yus-Díez, Konstantinos Eleftheriadis, Andrés Alastuey, Wenche Aas, Petra Pokorná, Naděžda Zíková, Petr Vodička, Evangelia Diapouli, Hilkka Timonen
article en

Abstract

Abstract Organic aerosol particles (OA) can absorb solar radiation with varying efficiencies depending on their chemical composition and physical properties. This light-absorbing fraction of OA, commonly referred to as brown carbon (BrC), is difficult to accurately represent in climate models due to the inherent diversity of its optical properties. This variability arises from differences in emission sources and atmospheric processing, as well as from variations in experimental design and the analytical methods used to quantify BrC absorption. As a result, the climate effect of BrC remains uncertain. Here, we studied the light absorption properties of surface ambient OA using measurements from 17 sites across Europe. Combining multi-wavelength absorption measurements from filter-based photometers with OA mass concentrations and source apportionment derived from ACSM/AMS data, we derive empirical estimates of the OA mass absorption cross section (MAC OA ), its wavelength dependence (AAE OA ), the OA density (⍴ OA ), and the MAC associated with different primary and secondary OA sources. We further develop parameterizations that relate MAC OA , AAE OA and ⍴ OA to the ambient black carbon-to-organic aerosol ratio (eBC/OA) and propose a corresponding parameterization for the imaginary refractive index (k OA ). Given the widespread availability of eBC and OA measurements in global monitoring networks, the framework presented here provides a practical approach for estimating the absorptive properties of surface OA particles under real-world conditions.

npj Climate and Atmospheric Science
Finnish Meteorological Institute (FI), Centre National de la Recherche Scientifique (FR), University of Helsinki (FI), Deutscher Wetterdienst (DE), Ollscoil na Gaillimhe – University of Galway (IE), University of Nova Gorica (SI), National Centre of Scientific Research "Demokritos" (GR), Aix-Marseille Université (FR), Commissariat à l'Énergie Atomique et aux Énergies Alternatives (FR), Jožef Stefan Institute (SI), Kjeller Innovasjon (Norway) (NO), Finnish Food Authority (FI), Institute of Atmospheric Sciences and Climate (IT), Czech Academy of Sciences, Global Change Research Institute (CZ), Estonian Environmental Research Center (Estonia) (EE), National Observatory of Athens (GR), Czech Academy of Sciences, Institute of Chemical Process Fundamentals (CZ), Laboratoire des Sciences du Climat et de l'Environnement (FR), Institut national de l'environnement industriel et des risques (FR), National Institute of Research and Development for Optoelectronics (RO), Tampere University (FI), Jolly Aero (Slovenia) (SI), Centrale Méditerranée (FR), Institute of Environmental Assessment and Water Research (ES), Department of Energy and Environment (US), National Research Council (IT), MRC Centre for Environment and Health, Imperial College London (GB), University of Tartu (EE), Swiss Federal Laboratories for Materials Science and Technology (CH), Universitat de Barcelona (ES), University of Birmingham (GB)
Ministerul Cercetării, Inovării şi Digitalizării, European Commission, European Cooperation in Science and Technology, Environmental Protection Agency, Agence Nationale de la Recherche, Academy of Finland, Javna Agencija za Raziskovalno Dejavnost RS, Ministerio de Ciencia e Innovación, Ministerio de Asuntos Económicos y Transformación Digital, Gobierno de España, Conseil Régional Hauts-de-France, Agència de Gestió d'Ajuts Universitaris i de Recerca, Horizon 2020, H2020 Marie Skłodowska-Curie Actions, HORIZON EUROPE European Innovation Council, HORIZON EUROPE European Research Council, Research Ireland
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Atmospheric chemistry and aerosols
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