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| Titel |
Measurements of cloud condensation nuclei (CCN) at the high-alpine site Jungfraujoch during CLACE-6 (2007) |
| VerfasserIn |
Diana Rose, Sachin Gunthe, Zsofia Juranyi, Martin Gysel, Göran Frank, Johannes Schneider, Joachim Curtius, Ulrich Pöschl |
| Konferenz |
EGU General Assembly 2014
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250091107
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| Publikation (Nr.) |
 EGU/EGU2014-5378.pdf |
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| Zusammenfassung |
| As part of the CLACE-6 campaign we performed size-resolved CCN measurements for a
supersaturation range of S=0.079% to 0.66% at the high-alpine research station Jungfraujoch,
Switzerland, in March 2007. The derived effective hygroscopicity parameter κ describing
the influence of particle composition on CCN activity was on average 0.23 – 0.30
for Aitken (50 – 100 nm) and 0.32 – 0.43 for accumulation mode particles (100 –
200 nm). The campaign average value of κ =0.3 is similar to the average value
of κ for other continental locations. When air masses came from southeasterly
directions crossing the Po Valley in Italy, particles were much more hygroscopic
(κ ~ 0.42) due to large sulfate mass fractions. The κ-values obtained at S=0.079%
exhibited a good negative correlation with the organic mass fractions derived from PM1
aerosol mass spectrometer (AMS) measurements. Applying a simple mixing rule
the organic and inorganic mass fractions observed by the AMS could be used to
reproduce the temporal fluctuations of the hygroscopicity of accumulation mode
particles quite well. We show how during a cloud event the aerosol particles were
activated as cloud droplets and then removed from the air by precipitation leaving
behind only a small amount of accumulation mode particles consisting mainly of
weakly CCN-active particles, most likely externally mixed unprocessed soot particles. |
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