A synthesis of cloud condensation nuclei counter (CCNC) measurements within the EUCAARI network

Autor: Ulrich Pöschl, Eija Asmi, Gregory Roberts, P. P. Aalto, Alfred Wiedensohler, Birgitta Svenningsson, Göran Frank, David Brus, B. Sierau, Liqing Hao, Nicholas Good, Cerina Wittbom, Athanasios Nenes, Nikos Mihalopoulos, Colin D. O'Dowd, Veli-Matti Kerminen, Z. Jurányi, Tuukka Petäjä, Meinrat O. Andreae, Erik Swietlicki, Stephen M. King, Urs Baltensperger, Adam Kristensson, Sachin S. Gunthe, A. Jaatinen, S. T. Martin, Jurgita Ovadnevaite, A. Kortelainen, Markku Kulmala, Diana Rose, Ulrike Lohmann, Gordon McFiggans, Mikhail Paramonov, Aikaterini Bougiatioti, M. Irwin, Ernest Weingartner, Heikki Lihavainen, J. D. Whitehead, Martin Gysel
Přispěvatelé: Aerosol-Cloud-Climate -Interactions (ACCI), Department of Physics, Faculty of Science and Forestry
Jazyk: angličtina
Rok vydání: 2015
Předmět:
Zdroj: Atmospheric Chemistry and Physics, Vol 15, Iss 21, Pp 12211-12229 (2015)
Atmospheric Chemistry and Physics, 15 (21)
Atmospheric Chemistry and Physics
ISSN: 1680-7324
1680-7316
Popis: Article
Cloud condensation nuclei counter (CCNC) measurements performed at 14 locations around the world within the European Integrated project on Aerosol Cloud Climate and Air Quality interactions (EUCAARI) framework have been analysed and discussed with respect to the cloud condensation nuclei (CCN) activation and hygroscopic properties of the atmospheric aerosol. The annual mean ratio of activated cloud condensation nuclei (NCCN) to the total number concentration of particles (NCN), known as the activated fraction A, shows a similar functional dependence on supersaturation S at many locations – exceptions to this being certain marine locations, a free troposphere site and background sites in south-west Germany and northern Finland. The use of total number concentration of particles above 50 and 100 nm diameter when calculating the activated fractions (A50 and A100, respectively) renders a much more stable dependence of A on S; A50 and A100 also reveal the effect of the size distribution on CCN activation. With respect to chemical composition, it was found that the hygroscopicity of aerosol particles as a function of size differs among locations. The hygroscopicity parameter κ decreased with an increasing size at a continental site in south-west Germany and fluctuated without any particular size dependence across the observed size range in the remote tropical North Atlantic and rural central Hungary. At all other locations κ increased with size. In fact, in Hyytiälä, Vavihill, Jungfraujoch and Pallas the difference in hygroscopicity between Aitken and accumulation mode aerosol was statistically significant at the 5 % significance level. In a boreal environment the assumption of a size-independent κ can lead to a potentially substantial overestimation of NCCN at S levels above 0.6 %. The same is true for other locations where κ was found to increase with size. While detailed information about aerosol hygroscopicity can significantly improve the prediction of NCCN, total aerosol number concentration and aerosol size distribution remain more important parameters. The seasonal and diurnal patterns of CCN activation and hygroscopic properties vary among three long-term locations, highlighting the spatial and temporal variability of potential aerosol–cloud interactions in various environments.
published version
http://purl.org/eprint/status/PeerReviewed
Databáze: OpenAIRE
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