EGU General Assembly 2020
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

Global variability of aerosol optical properties retrieved from the network of GAW near-surface observatories

Alessandro Bigi1, Martine Collaud Coen2, Elisabeth J. Andrews3,4, Clémence Rose5, Cathrine Lund Myhre6, Markus Fiebig6, Michael Schulz7, John A. Ogren4, Jonas Gliss7, Augustin Mortier7, Alfred Wiedensohler8, Marco Pandolfi9, Tuukka Petäja10, Sang-Woo Kim11, Wenche Aas6, Jean-Philippe Putaud12, Olga Mayol-Bracero13, Melita Keywood14, Lorenzo Labrador15, and Paolo Laj10,16,17
Alessandro Bigi et al.
  • 1Università degli Studi di Modena e Reggio Emilia, Dipartimento di Ingegneria "Enzo Ferrari", Modena, Italy (
  • 2Federal Office of Meteorology and Climatology, MeteoSwiss, Payerne, Switzerland
  • 3Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, Colorado, USA
  • 4NOAA/Earth Systems Research Laboratory, Boulder, CO, USA
  • 5Université Clermont-Auvergne, CNRS, LaMP, OPGC, Clermont-Ferrand, France
  • 6NILU, Norwegian Institute for Air Research, Kjeller, Norway
  • 7Norwegian Meteorological Institute, Oslo, Norway
  • 8Institute for Tropospheric Research, Leipzig, Germany
  • 9Institute of Environmental Assessment and Water Research (IDAEA), Spanish Research Council (CSIC), Barcelona, Spain
  • 10Institute for Atmospheric and Earth System Research, University of Helsinki, Helsinki, Finland
  • 11School of Earth and Environmental Sciences, Seoul National University, Seoul, Korea
  • 12European Commission, Joint Research Centre (JRC), Ispra, Italy
  • 13University of Puerto Rico, Rio Piedras Campus, San Juan, Puerto Rico
  • 14CSIRO Oceans and Atmosphere, PMB1 Aspendale VIC, Australia
  • 15World Meteorological Organisation, Global Atmosphere Watch Secretariat, Geneva, Switzerland
  • 16Univ. Grenoble-Alpes, CNRS, IRD, Grenoble-INP, IGE, 38000 Grenoble, France
  • 17Institute of Atmospheric Sciences and Climate, National Research Council of Italy, Bologna, Italy

Atmospheric aerosols are known to play a key role in Earth’s radiative budget, although the quantification of their climate forcing is still highly uncertain. In order to improve the scientific understanding of their climatic effect, in-situ ground-based aerosol properties observations are needed by the research community. Such data would also allow the global assessment of the effect of environmental policies over both the short and the long term.

To develop a robust and consistent view over time of the worldwide variability of aerosol properties, data resulting from a fully-characterized value chain, including uncertainty estimation, is needed.

The present work is part of a wider project, having among its goals the investigation of the variability of climate-relevant aerosol properties observed at all sites connected to the Global Atmospheric Watch network, whose data are publicly available from the World Data Centre for Aerosols and follow the aforementioned specifications.

This work focuses on aerosol optical proprieties, i.e. the aerosol light scattering coefficient (σsp), the aerosol light absorption coefficient (σap), single scattering albedo (ωo) and both scattering and absorption Ångström exponents (åsp and åap).

The analysis includes 108 yearly datasets collected either during 2016 or 2017 at different sites: 53 for absorption and 55 for scattering coefficient datasets, respectively. For 29 of these sites it was also possible to compute single scattering albedo.

The spatial variability in extensive and intensive optical properties was analysed in terms of each site’s geographical location (either polar, continental, coastal or mountain) and its footprint (from pristine to urban, representing increasing levels of anthropogenic influence).

The results highlight the impact of anthropogenic emissions and biomass burning on absolute levels and annual variability. The effect of sea spray or long range transport of dust is also evident for several sites, along with the influence of regional emissions. The largest seasonality in aerosol loading was observed at mountain sites under mixed footprint conditions, while the lowest seasonality occurred at urban sites. Urban sites also exhibited the highest σsp and σap values. The lowest levels in σsp and σap were observed at some polar sites, along with few coastal and mountain sites, despite their typically mixed footprint.


The authors acknowledge WMO-GAW World Data Centre on Aerosol for providing data available at

How to cite: Bigi, A., Collaud Coen, M., Andrews, E. J., Rose, C., Lund Myhre, C., Fiebig, M., Schulz, M., Ogren, J. A., Gliss, J., Mortier, A., Wiedensohler, A., Pandolfi, M., Petäja, T., Kim, S.-W., Aas, W., Putaud, J.-P., Mayol-Bracero, O., Keywood, M., Labrador, L., and Laj, P.: Global variability of aerosol optical properties retrieved from the network of GAW near-surface observatories, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-3568,, 2020.


Display file

Comments on the display

AC: Author Comment | CC: Community Comment | Report abuse

displays version 1 – uploaded on 02 May 2020, no comments