Results from the CERN pilot CLOUD experiment

Autor(en)

Jonathan Duplissy, Martin Andreas Bødker Enghoff, Karen L. Aplin, F. Arnold, Heinfried Aufmhoff, Michael Hassel Avngaard, Urs Baltensperger, Torsten Bondo, Robert J. Bingham, Ken Carslaw, Joachim Curtius, A. David, B. Fastrup, Stéphanie Gagne, F. Hahn, R.Giles Harrison, Barry Kellett, J. Kirby, Markku Kulmala, Lauri Laakso, Ari Laaksonen, Egil Lillestol, Mike Lockwood, Jyrki Mäkelä, Vladimir S. Makhmutov, Nigel D. Marsh, Tuomo Nieminen, Antti Onnela, E. Pedersen, Jens Olaf Pepke Pedersen, Josef Polny, Ulrike Reichl, John H. Seinfeld, Mikko Sipilä, Yurii Ivanovich Stozhkov, Frank Stratmann, Henrik Svensmark, J. Svensmark, R. Veenhof, Bart Verheggen, Yirö Viisanen, Paul Wagner, G. Wehrle, Ernest Weingartner, Heike Wex, M. Wilhelmsson, Paul Winkler

Abstrakt

During a 4-week run in October–November 2006, a pilot experiment was performed at the CERN Proton Synchrotron in preparation for the Cosmics Leaving OUtdoor Droplets (CLOUD) experiment, whose aim is to study the possible influence of cosmic rays on clouds. The purpose of the pilot experiment was firstly to carry out exploratory measurements of the effect of ionising particle radiation on aerosol formation from trace H2SO4 vapour and secondly to provide technical input for the CLOUD design. A total of 44 nucleation bursts were produced and recorded, with formation rates of particles above the 3 nm detection threshold of between 0.1 and 100 cm−3s−1, and growth rates between 2 and 37 nm h−1. The corresponding H2O concentrations were typically around 106 cm−3 or less. The experimentally-measured formation rates and \htwosofour concentrations are comparable to those found in the atmosphere, supporting the idea that sulphuric acid is involved in the nucleation of atmospheric aerosols. However, sulphuric acid alone is not able to explain the observed rapid growth rates, which suggests the presence of additional trace vapours in the aerosol chamber, whose identity is unknown. By analysing the charged fraction, a few of the aerosol bursts appear to have a contribution from ion-induced nucleation and ion-ion recombination to form neutral clusters. Some indications were also found for the accelerator beam timing and intensity to influence the aerosol particle formation rate at the highest experimental SO2 concentrations of 6 ppb, although none was found at lower concentrations. Overall, the exploratory measurements provide suggestive evidence for ion-induced nucleation or ion-ion recombination as sources of aerosol particles. However in order to quantify the conditions under which ion processes become significant, improvements are needed in controlling the experimental variables and in the reproducibility of the experiments. Finally, concerning technical aspects, the most important lessons for the CLOUD design include the stringent requirement of internal cleanliness of the aerosol chamber, as well as maintenance of extremely stable temperatures (variations below 0.1 °C).

Organisation(en)

Aerosolphysik und Umweltphysik

Externe Organisation(en)

European Organization for Nuclear Research (CERN), Technical University of Denmark (DTU), Rutherford Appleton Laboratory, Max-Planck-Institut für Kernphysik, Paul Scherrer Institute, University of Leeds, Johann Wolfgang Goethe-Universität Frankfurt am Main, University of Helsinki, University of Reading, University of Eastern Finland, University of Bergen (UiB), Tampere University of Technology (TUT), Lebedev Physical Institute, Aarhus University, California Institute of Technology (Caltech), Leibniz-Institut für Troposphärenforschung, Finnish Meteorological Institute

Journal

Atmospheric Chemistry and Physics

Band

10

Seiten

1635-1647

Anzahl der Seiten

13

ISSN

1680-7316

DOI

https://doi.org/10.5194/acp-10-1635-2010

Publikationsdatum

2010

Peer-reviewed

Ja

ÖFOS 2012

104017 Physikalische Chemie, 103008 Experimentalphysik, 105204 Klimatologie

Link zum Portal

https://ucrisportal.univie.ac.at/de/publications/95afcd75-e784-4883-be98-23866f5e1712