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| Titel |
An investigation of processes controlling the evolution of the boundary layer aerosol size distribution properties at the Swedish background station Aspvreten |
| VerfasserIn |
P. Tunved, J. Ström, H.-C. Hansson |
| 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 ; 4, no. 11/12 ; Nr. 4, no. 11/12 (2004-12-20), S.2581-2592 |
| Datensatznummer |
250001432
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| Publikation (Nr.) |
 copernicus.org/acp-4-2581-2004.pdf |
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| Zusammenfassung |
| Aerosol size distributions have been measured at the Swedish background
station Aspvreten (58.8° N, 17.4° E). Different states of the
aerosol were determined using a novel application of cluster analysis. The
analysis resulted in eight different clusters capturing different stages of
the aerosol lifecycle. The atmospheric aerosol size distributions were
interpreted as belonging to fresh, intermediate and aged types of size
distribution. With aid of back trajectory analysis we present statistics
concerning the relation of source area and different meteorological
parameters using a non-Lagrangian approach. Source area is argued to be
important although not sufficient to describe the observed aerosol
properties. Especially processing by clouds and precipitation is shown to be
crucial for the evolution of the aerosol size distribution. As much as
60% of the observed size distributions present features that are likely
to be related to cloud processes or wet deposition. The lifetime properties
of different sized aerosols are discussed by means of measured variability
of the aerosol size distribution. Processing by clouds and precipitation is
shown to be especially crucial in the size range 100 nm and larger. This
indicates an approximate limit for activation in clouds to 100 nm in this
type of environment. The aerosol lifecycle is discussed. Size distributions
indicating signs of recent new particle formation (~30% of the
observed size distributions) represent the first stage in the lifecycle.
Aging of the aerosol size distribution may follow two branches: either
growth by condensation and coagulation or processing by non-precipitating
clouds. In both cases mass is accumulated. Wet removal is the main process
capable of removing aerosol mass. Wet deposition is argued to be an
important mechanism in reaching a state where nucleation may occur (i.e.
sufficiently low aerosol surface area) in environments similar to the one
studied. |
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