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| Titel |
Field measurements of hygroscopic properties and state of mixing of nucleation mode particles |
| VerfasserIn |
M. Väkevä, M. Kulmala  , F. Stratmann, K. Hämeri |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1680-7316
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 2, no. 1 ; Nr. 2, no. 1 (2002-02-27), S.55-66 |
| Datensatznummer |
250000371
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| Publikation (Nr.) |
 copernicus.org/acp-2-55-2002.pdf |
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| Zusammenfassung |
| An Ultrafine Tandem Differential Mobility Analyser
(UF-TDMA) has been used in several field campaigns over the last few years. The
investigations were focused on the origin and properties of nucleation event aerosols, which are observed frequently in
various environments. This paper gives a summary of the results of 10 nm and
20 nm particle hygroscopic properties from different measurement sites: an urban site, an urban
background site and a forest site in Finland and a coastal site in western Ireland. The data can be classified in four hygroscopic
growth classes: hydrofobic, less-hygroscopic, more-hygroscopic and sea-salt. Similar classification has been earlier presented for
Aitken and accumulation mode particles. In urban air, the summertime 10 nm particles showed varying less-hygroscopic
growth behaviour, while winter time 10 nm and 20 nm particles were externally mixed with two different
hygroscopic growth modes. The forest measurements revealed diurnal behaviour of hygroscopic growth, with high growth factors at day
time and lower during night. The urban background particles had growth behaviour similar to the urban and forest measurement sites
depending on the origin of the observed particles. The coastal measurements were strongly affected by air mass history. Both
10 nm and 20 nm particles were hygroscopic in marine background air. The
10 nm particles produced during clean nucleation burst periods were hydrofobic. Diurnal variation
and higher growth factors of 10 nm particles were observed in air affected by other source regions. External mixing was
occasionally observed at all the sites, but incidents with more than two growth modes were extremely rare. |
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