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| Titel |
Aerosol hygroscopicity and CCN activation kinetics in a boreal forest environment during the 2007 EUCAARI campaign |
| VerfasserIn |
K. M. Cerully, T. Raatikainen, S. Lance, D. Tkacik, P. Tiitta, T. Petäjä, M. Ehn, M. Kulmala  , D. R. Worsnop, A. Laaksonen, J. N. Smith, A. Nenes |
| 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 ; 11, no. 23 ; Nr. 11, no. 23 (2011-12-09), S.12369-12386 |
| Datensatznummer |
250010255
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| Publikation (Nr.) |
 copernicus.org/acp-11-12369-2011.pdf |
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| Zusammenfassung |
| Measurements of size-resolved cloud condensation nuclei (CCN) concentrations,
subsaturated hygroscopic growth, size distribution, and chemical composition
were collected from March through May, 2007, in the remote Boreal forests of
Hyytiälä, Finland, as part of the European Integrated project on
Aerosol Cloud Climate and Air Quality Interactions (EUCAARI) campaign.
Hygroscopicity parameter, κ, distributions were derived
independently from Continuous Flow-Streamwise Thermal Gradient CCN Chamber
(CFSTGC) and Hygroscopicity Tandem Differential Mobility Analyzer (HTDMA)
measurements. CFSTGC-derived κ values for 40, 60, and 80 nm
particles range mostly between 0.10 and 0.40 with an average characteristic
of highly oxidized organics of 0.20 ± 0.10, indicating that organics
play a dominant role for this environment. HTDMA-derived κ were
generally 30% lower. Diurnal trends of κ show a minimum at
sunrise and a maximum in the late afternoon; this trend covaries with
inorganic mass fraction and the m/z 44 organic mass fraction given
by a quadrupole aerosol mass spectrometer, further illustrating the
importance of organics in aerosol hygroscopicity. The chemical dispersion
inferred from the observed κ distributions indicates that while 60
and 80 nm dispersion increases around midday, 40 nm dispersion remains
constant. Additionally, 80 nm particles show a markedly higher level of
chemical dispersion than both 40 and 60 nm particles. An analysis of droplet
activation kinetics for the sizes considered indicates that most of the CCN
activate as rapidly as (NH4)2SO4 calibration aerosol. |
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