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| Titel |
The effect of local sources on particle size and chemical composition and their role in aerosol–cloud interactions at Puijo measurement station |
| VerfasserIn |
H. Portin, A. Leskinen, L. Hao, A. Kortelainen, P. Miettinen, A. Jaatinen, A. Laaksonen, K. E. J. Lehtinen, S. Romakkaniemi, M. Komppula |
| 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 ; 14, no. 12 ; Nr. 14, no. 12 (2014-06-18), S.6021-6034 |
| Datensatznummer |
250118817
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| Publikation (Nr.) |
 copernicus.org/acp-14-6021-2014.pdf |
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| Zusammenfassung |
| Interactions between aerosols and liquid water clouds were studied during
autumns 2010–2011 at a semiurban measurement station on Puijo tower in
Kuopio, Finland. Cloud interstitial and total aerosol size distributions,
particle chemical composition and hygroscopicity and cloud droplet size
distribution were measured, with a focus on comparing clean air masses with
those affected by local sources. On average, the polluted air contained more
particles than the clean air masses, and generally the concentrations
decreased during cloud events. Cloud processing was found to take place,
especially in the clean air masses, and to a lesser extent in the polluted
air. Some, mostly minor, differences in the average particle chemical
composition between the air masses were observed. The average size and
number concentration of activating particles were quite similar for both air
masses, producing average droplet populations with only minor distinctions.
As a case study, a long cloud event was analyzed in detail, with a special
focus on the emissions from local sources, including a paper mill and a
heating plant. This revealed larger variations in particle and cloud
properties than the analysis of the whole data set. Clear differences in the
total (between 214 and 2200 cm−3) and accumulation mode particle
concentrations (between 62 and 169 cm−3) were observed. Particle
chemical composition, especially the concentrations of organics (between
0.42 and 1.28 μg m−3) and sulfate (between 0.16 and 4.43 μg m−3), varied considerably. This affected the hygroscopic
growth factor: for example, for 100 nm particles the range was from 1.21 to 1.45 at
90% relative humidity. Particularly, large particles, high
hygroscopicities and elevated amounts of inorganics were linked with the
pollutant plumes. Moreover, the particle hygroscopicity distributions in the
polluted air were clearly bimodal, indicating externally mixed aerosol. The
variable conditions also had an impact on cloud droplet formation, with the
droplet concentration varying between 138 and 240 cm−3 and mean
diameter between 9.2 and 12.4 μm. |
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