New particle formation and ultrafine charged aerosol climatology at a high altitude site in the Alps (Jungfraujoch, 3580 m a.s.l., Switzerland)

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Authors
Boulon, Julien
Sellegri, Karine
Venzac, Hervé
Picard, David
Wehrle, Günther
Collaud Coen, Martine
Bütikofer, Rolf
Flückiger, Erwin
Baltensperger, Urs
Author (Corporation)
Publication date
05.10.2010
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01A - Journal article
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Parent work
Atmospheric Chemistry and Physics
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Volume
10
Issue / Number
19
Pages / Duration
9333-9349
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Publisher / Publishing institution
Copernicus
Place of publication / Event location
Göttingen
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Abstract
We investigate the formation and growth of charged aerosols clusters at Jungfraujoch, in the Swiss Alps (3580 m a.s.l.), the highest altitude site of the European EUCAARI project intensive campaign. Charged particles and clusters (0.5–1.8 nm) were measured from April 2008 to April 2009 and allowed the detection of nucleation events in this very specific environment (presence of free tropospheric air and clouds). We found that the naturally charged aerosol concentrations, which are dominated by the cluster size class, shows a strong diurnal pattern likely linked to valley breezes transporting surface layer ion precursors, presumably radon. Cosmic rays were found not to be the major ion source at the measurement site. However, at night, when air masses are more representative of free tropospheric conditions, we found that the cluster concentrations are still high. The charged aerosol size distribution and concentration are strongly influenced by the presence of clouds at the station. Clouds should be taken into account when deriving high altitude nucleation statistics. New particle formation occurs on average 17.5% of the measurement period and shows a weak seasonality with a minimum of frequency during winter, but this seasonality is enhanced when the data set is screened for periods when the atmospheric station is out of clouds. The role of ions in the nucleation process was investigated and we found that the ion-mediated nucleation explains 22.3% of the particle formation. The NPF events frequency is correlated with UV radiation but not with calculated H2SO4 concentrations, suggesting that other compounds such as organic vapors are involved in the nucleation and subsequently growth process. In fact, NPF events frequency also surprisingly increases with the condensational sink (CS), suggesting that at Jungfraujoch, the presence of condensing vapours probably coupled with high CS are driving the occurrence of NPF events. A strong link to the air mass path was also pointed out and events were observed to be frequently occurring in Eastern European air masses, which present the highest condensational sink. In these air masses, pre-existing cluster concentrations are more than three time larger than in other air masses during event days, and no new clusters formation is observed, contrarily to what is happening in other air mass types.
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Subject (DDC)
550 - Geowissenschaften
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ISBN
ISSN
1680-7324
1680-7316
Language
English
Created during FHNW affiliation
No
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Publication status
Published
Review
Peer review of the complete publication
Open access category
Gold
License
'https://creativecommons.org/licenses/by/4.0/'
Citation
BOULON, Julien, Karine SELLEGRI, Hervé VENZAC, David PICARD, Ernest WEINGARTNER, Günther WEHRLE, Martine COLLAUD COEN, Rolf BÜTIKOFER, Erwin FLÜCKIGER, Urs BALTENSPERGER und Paolo LAJ, 2010. New particle formation and ultrafine charged aerosol climatology at a high altitude site in the Alps (Jungfraujoch, 3580 m a.s.l., Switzerland). Atmospheric Chemistry and Physics. 5 Oktober 2010. Bd. 10, Nr. 19, S. 9333–9349. DOI 10.5194/acp-10-9333-2010. Verfügbar unter: https://doi.org/10.26041/fhnw-9678