Results from the CERN pilot CLOUD experiment

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 H2SO4 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).

Schlagwörter

Fachgebiet (DDC)

550 - Geowissenschaften

Projekt

Veranstaltung

Startdatum der Ausstellung

Enddatum der Ausstellung

Startdatum der Konferenz

Enddatum der Konferenz

Datum der letzten Prüfung

ISBN

ISSN

1680-7324
1680-7316

Sprache

Englisch

Während FHNW Zugehörigkeit erstellt

Nein

Publikationsstatus

Veröffentlicht

Begutachtung

Peer-Review der ganzen Publikation

Open Access-Status

Gold

Lizenz

Zitation

DUPLISSY, Jonathan, Martin Bødker ENGHOFF, Karen L. APLIN, Frank ARNOLD, Heinfried AUFMHOFF, Michael AVNGAARD, Urs BALTENSPERGER, Torsten BONDO, Robert BINGHAM, Ken S. CARSLAW, Joachim CURTIUS, A. DAVID, Bent FASTRUP, Stéphanie GAGNÉ, F. HAHN, Richerd Giles HARRISON, Barry KELLETT, Jasper KIRKBY, Markku KULMALA, Lauri LAAKSO, Ari LAAKSONEN, Egil LILLESTØL, Mike LOCKWOOD, Jyrki Mikael MÄKELÄ, Vladimir MAKHMUTOV, N. D. MARSH, Tuomo NIEMINEN, Antti ONNELA, E. PEDERSEN, Jens Olaf Pepke PEDERSEN, Josef POLNY, Udo REICHL, John H. SEINFELD, Mikko SIPILÄ, Yuri STOZHKOV, Frank STRATMANN, Henrik SVENSMARK, Jacob SVENSMARK, Rob VEENHOF, B. VERHEGGEN, Yrjö VIISANEN, Paul E. WAGNER, Günther WEHRLE, Ernest WEINGARTNER, Heike WEX, Mats WILHELMSSON und Paul M. WINKLER, 2010. Results from the CERN pilot CLOUD experiment. Atmospheric Chemistry and Physics. 15 Februar 2010. Bd. 10, Nr. 4, S. 1635–1647. DOI 10.5194/acp-10-1635-2010. Verfügbar unter: https://doi.org/10.26041/fhnw-9680

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