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| Titel |
New particle formation in air mass transported between two measurement sites in Northern Finland |
| VerfasserIn |
M. Komppula, S.-L. Sihto, H. Korhonen, H. Lihavainen, V.-M. Kerminen, M. Kulmala  , Y. Viisanen |
| 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 ; 6, no. 10 ; Nr. 6, no. 10 (2006-07-10), S.2811-2824 |
| Datensatznummer |
250004000
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| Publikation (Nr.) |
 copernicus.org/acp-6-2811-2006.pdf |
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| Zusammenfassung |
| This study covers four years of aerosol number size distribution data from
Pallas and Värriö sites 250 km apart from each other in Northern
Finland and compares new particle formation events between these sites. In
air masses of eastern origin almost all events were observed to start
earlier at the eastern station Värriö, whereas in air masses of
western origin most of the events were observed to start earlier at the
western station Pallas. This demonstrates that particle formation in a
certain air mass type depends not only on the diurnal variation of the
parameters causing the phenomenon (such as photochemistry) but also on some
properties carried by the air mass itself. The correlation in growth rates
between the two sites was relatively good, which suggests that the amount of
condensable vapour causing the growth must have been at about the same level
in both sites. The condensation sink was frequently much higher at the
downwind station. It seems that secondary particle formation related to
biogenic sources dominate in many cases over the particle sinks during the
air mass transport between the sites. Two cases of transport from Pallas to
Värriö were further analysed with an aerosol dynamics model. The
model was able to reproduce the observed nucleation events 250 km down-wind
at Värriö but revealed some differences between the two cases. The
simulated nucleation rates were in both cases similar but the organic
concentration profiles that best reproduced the observations were different
in the two cases indicating that divergent formation reactions may dominate
under different conditions. The simulations also suggested that organic
compounds were the main contributor to new particle growth, which offers a
tentative hypothesis to the distinct features of new particles at the two
sites: Air masses arriving from the Atlantic Ocean typically spent
approximately only ten hours over land before arriving at Pallas, and thus
the time for the organic vapours to accumulate in the air and to interact
with the particles is relatively short. This can lead to low nucleation mode
growth rates and even to suppression of detectable particle formation event
due to efficient scavenging of newly formed clusters, as was observed in the
case studies. |
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