24 Mar 2022
24 Mar 2022
Status: this preprint is currently under review for the journal ACP.

Comparison of particle number size distribution trends in ground measurements and climate models

Ville Leinonen1, Harri Kokkola2, Taina Yli-Juuti1, Tero Mielonen2, Thomas Kühn1,2, Tuomo Nieminen3, Simo Heikkinen1, Tuuli Miinalainen1, Tommi Bergman4,5, Ken Carslaw6, Stefano Decesari7, Markus Fiebig8, Tareq Hussein9,10, Niku Kivekäs11, Markku Kulmala9, Ari Leskinen2,1, Andreas Massling12, Nikos Mihalopoulos13, Jane P. Mulcahy14, Steffen M. Noe15, Twan van Noije5, Fiona M. O'Connor14, Colin O'Dowd16, Dirk Olivie17, Jakob B. Pernov12,a, Tuukka Petäjä9, Øyvind Seland17, Michael Schulz17, Catherine E. Scott6, Henrik Skov12, Erik Swietlicki18, Thomas Tuch19, Alfred Wiedensohler19, Annele Virtanen1, and Santtu Mikkonen1,20 Ville Leinonen et al.
  • 1Department of Applied Physics, University of Eastern Finland, Kuopio, Finland
  • 2Finnish Meteorological Institute, Kuopio, Finland
  • 3Institute for Atmospheric and Earth System Research, University of Helsinki, Helsinki, Finland
  • 4Climate System Research, Finnish Meteorological Institute, Helsinki, Finland
  • 5Royal Netherlands Meteorological Institute, De Bilt, Netherlands
  • 6Institute for Climate and Atmospheric Science, School of Earth and Environment, University of Leeds, Leeds, UK
  • 7Institute of Atmospheric and Climate Sciences (ISAC) of the National Research Council of Italy (CNR), Bologna, Italy
  • 8Department of Atmospheric and Climate Research, NILU-Norwegian Institute for Air Research, Kjeller, Norway
  • 9Institute for Atmospheric and Earth System Research/Physics, Faculty of Science, University of Helsinki, Helsinki, Finland
  • 10Department of Physics, the University of Jordan, Amman 11942, Jordan
  • 11Finnish Meteorological Institute, Helsinki, Finland
  • 12Department of Environmental Science, iClimate, Aarhus University, Denmark
  • 13Environmental Chemical Processes Laboratory (ECPL), Chemistry Department, University of Crete, Heraklion, Crete, Greece
  • 14Met Office Hadley Centre, Exeter, United Kingdom
  • 15Institute of Forestry and Engineering, Estonian University of Life Sciences, Tartu, Estonia
  • 16School of Natural Sciences and Ryan Institutes Centre for Climate and Air Pollution Studies, National University of Ireland Galway, Galway, Ireland
  • 17Norwegian Meteorological Institute, Oslo, Norway
  • 18Division of Nuclear Physics, Physics Department, Lund University, Lund, Sweden
  • 19Leibniz Institute for Tropospheric Research, Leipzig, Germany
  • 20Department of Environmental and Biological Sciences, University of Eastern Finland, Kuopio, Finland
  • anow at: Extreme Environments Research Laboratory, École Polytechnique fédérale de Lausanne, 1951 Sion, Switzerland

Abstract. Despite a large number of studies, the effect of aerosols has the largest uncertainty in global climate model radiative forcing estimates. There have been studies of aerosol optical properties in climate models, but the effects of particle number size distribution need a more thorough inspection. We investigated the trends and seasonality of particle number concentrations in different sizes in total of for 21 measurement sites in Europe and Arctic. For 13 of those, with longer measurement time series, we compared the field observations with the results from five climate models, namely EC-Earth3, ECHAM-M7, ECHAM-SALSA, NorESM1.2, and UKESM1. This is the first extensive comparison of detailed aerosol size distribution trends between in-situ observations from Europe and five earth system models (ESM). We found that the trends of particle number concentrations were mostly consistent and decreasing in both, measurements and models. However, for many sites, climate models showed weaker decreasing trends than the measurements. Seasonal variability in measured number concentrations, quantified by the ratio between maximum and minimum monthly number concentration, were typically stronger in northern measurement sites compared to other locations. Models had large differences in their seasonal representation, and they can be roughly divided into two categories. For EC-Earth and NorESM, the seasonal cycle was relatively similar for all sites, for others, the pattern of seasonality varied between northern and southern sites. In addition, the variability in concentrations across sites varied between models, some having relatively similar concentrations for all sites, whereas others showing clear differences in concentrations between remote and urban sites. To conclude, although anthropogenic mass emissions are harmonized in models, trends in different sized particles vary among the model due to assumptions in emission sizes and differences in how models treat size dependent aerosol processes. The inter-model variability was largest in the accumulation mode, i.e. sizes which have implications for aerosol-cloud interactions.

Ville Leinonen et al.

Status: open (extended)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on acp-2022-225', Anonymous Referee #1, 03 May 2022 reply

Ville Leinonen et al.

Ville Leinonen et al.


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Short summary
We provide the first extensive comparison of detailed aerosol size distribution trends between in-situ observations from Europe and five different earth system models. We investigated commonly used aerosol modes (nucleation, Aitken, and accumulation) separately and were able to show the differences between measured and modeled trends and especially their seasonal patterns. This provides an important addition to earlier aerosol-cloud interaction model evaluation studies.