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| Titel |
New particle formation and growth at a remote, sub-tropical coastal location |
| VerfasserIn |
R. L. Modini, Z. D. Ristovski, G. R. Johnson, C. He, N. Surawski, L. Morawska, T. Suni, M. Kulmala  |
| 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 ; 9, no. 19 ; Nr. 9, no. 19 (2009-10-12), S.7607-7621 |
| Datensatznummer |
250007681
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| Publikation (Nr.) |
 copernicus.org/acp-9-7607-2009.pdf |
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| Zusammenfassung |
| A month-long intensive measurement campaign was conducted in March/April
2007 at Agnes Water, a remote coastal site just south of the Great Barrier
Reef on the east coast of Australia. Particle and ion size distributions
were continuously measured during the campaign. Coastal nucleation events
were observed in clean, marine air masses coming from the south-east on
65% of the days. The events usually began at ~10:00 local time and
lasted for 1–4 h. They were characterised by the appearance of a
nucleation mode with a peak diameter of ~10 nm. The freshly nucleated
particles grew within 1–4 h up to sizes of 20–50 nm. The events occurred
when solar intensity was high (~1000 W m−2) and RH was low (~60%).
Interestingly, the events were not related to tide height. The
volatile and hygroscopic properties of freshly nucleated particles
(17–22.5 nm), simultaneously measured with a volatility-hygroscopicity-tandem
differential mobility analyser (VH-TDMA), were used to infer chemical
composition. The majority of the volume of these particles was attributed to
internally mixed sulphate and organic components. After ruling out
coagulation as a source of significant particle growth, we conclude that the
condensation of sulphate and/or organic vapours was most likely responsible
for driving particle growth at sizes greater than 10 nm during the
nucleation events. Although there was a possibility that the precursor
vapours responsible for particle formation and growth had continental
sources, on the balance of available data we would suggest that the
precursors were most likely of marine/coastal origin. Furthermore, a unique
and particularly strong nucleation event was observed during northerly wind.
The event began early one morning (08:00) and lasted almost the entire day
resulting in the production of a large number of ~80 nm particles
(average modal concentration during the event was 3200 cm−3). The Great
Barrier Reef was the most likely source of precursor vapours responsible for
this event. |
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