Long-term cloud condensation nuclei number concentration, particle number size distribution and chemical composition measurements at regionally representative observatories

Forskningsoutput: TidskriftsbidragArtikel i vetenskaplig tidskrift

Abstract

Aerosol-cloud interactions (ACI) constitute the single largest uncertainty in anthropogenic radiative forcing. To reduce the uncertainties and gain more confidence in the simulation of ACI, models need to be evaluated against observations, in particular against measurements of cloud condensation nuclei (CCN). Here we present a data set - ready to be used for model validation - of long-term observations of CCN number concentrations, particle number size distributions and chemical composition from 12 sites on 3 continents. Studied environments include coastal background, rural background, alpine sites, remote forests and an urban surrounding. Expectedly, CCN characteristics are highly variable across site categories. However, they also vary within them, most strongly in the coastal background group, where CCN number concentrations can vary by up to a factor of 30 within one season. In terms of particle activation behaviour, most continental stations exhibit very similar activation ratios (relative to particles 20nm) across the range of 0.1 to 1.0% supersaturation. At the coastal sites the transition from particles being CCN inactive to becoming CCN active occurs over a wider range of the supersaturation spectrum. Several stations show strong seasonal cycles of CCN number concentrations and particle number size distributions, e.g. at Barrow (Arctic haze in spring), at the alpine stations (stronger influence of polluted boundary layer air masses in summer), the rain forest (wet and dry season) or Finokalia (wildfire influence in autumn). The rural background and urban sites exhibit relatively little variability throughout the year, while short-term variability can be high especially at the urban site. The average hygroscopicity parameter, calculated from the chemical composition of submicron particles was highest at the coastal site of Mace Head (0.6) and lowest at the rain forest station ATTO (0.2-0.3). We performed closure studies based on -Köhler theory to predict CCN number concentrations. The ratio of predicted to measured CCN concentrations is between 0.87 and 1.4 for five different types of . The temporal variability is also well captured, with Pearson correlation coefficients exceeding 0.87. Information on CCN number concentrations at many locations is important to better characterise ACI and their radiative forcing. But long-term comprehensive aerosol particle characterisations are labour intensive and costly. Hence, we recommend operating migrating-CCNCs to conduct collocated CCN number concentration and particle number size distribution measurements at individual locations throughout one year at least to derive a seasonally resolved hygroscopicity parameter. This way, CCN number concentrations can only be calculated based on continued particle number size distribution information and greater spatial coverage of long-term measurements can be achieved.

Detaljer

Författare
  • Julia Schmale
  • Silvia Henning
  • Stefano Decesari
  • Bas Henzing
  • Helmi Keskinen
  • Karine Sellegri
  • Jurgita Ovadnevaite
  • Mira Pöhlker
  • Joel Brito
  • Aikaterini Bougiatioti
  • Nikos Kalivitis
  • Iasonas Stavroulas
  • Samara Carbone
  • Anne Jefferson
  • Minsu Park
  • Patrick Schlag
  • Yoko Iwamoto
  • Pasi Aalto
  • Mikko Äijälä
  • Nicolas Bukowiecki
  • Mikael Ehn
  • Roman Fröhlich
  • Arnoud Frumau
  • Erik Herrmann
  • Hartmut Herrmann
  • Rupert Holzinger
  • Gerard Kos
  • Markku Kulmala
  • Nikolaos Mihalopoulos
  • Athanasios Nenes
  • Colin O'Dowd
  • Tuukka Petäjä
  • David Picard
  • Christopher Pöhlker
  • Ulrich Pöschl
  • Laurent Poulain
  • Meinrat Andreae
  • Paulo Artaxo
  • Alfred Wiedensohler
  • John Ogren
  • Atsushi Matsuki
  • Seong Soo Yum
  • Frank Stratmann
  • Urs Baltensperger
  • Martin Gysel
Enheter & grupper
Externa organisationer
  • Paul Scherrer Institute
  • Leibniz Institute for Tropospheric Research
  • Institute of Atmospheric Sciences and Climate
  • Netherlands Organisation for Applied Scientific Research
  • University of Helsinki
  • University of Auvergne
  • National University of Ireland Galway
  • Max Planck Institute for Chemistry
  • University of São Paulo
  • University of Crete
  • National Oceanic and Atmospheric Administration (NOAA)
  • Yonsei University
  • Utrecht University
  • Jülich Research Centre
  • Hiroshima University
  • Energy Research Centre of the Netherlands
  • National Observatory of Athens
  • Georgia Institute of Technology
  • Foundation for Research and Technology - Hellas
  • Kanazawa University
Forskningsområden

Ämnesklassifikation (UKÄ) – OBLIGATORISK

  • Meteorologi och atmosfärforskning
Originalspråkengelska
Sidor (från-till)2853-2881
Antal sidor29
TidskriftAtmospheric Chemistry and Physics
Volym18
Utgåva nummer4
StatusPublished - 2018 feb 28
PublikationskategoriForskning
Peer review utfördJa