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| Titel |
A long-term satellite study of aerosol effects on convective clouds in Nordic background air |
| VerfasserIn |
M. K. Sporre, E. Swietlicki, P. Glantz, 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 ; 14, no. 4 ; Nr. 14, no. 4 (2014-02-28), S.2203-2217 |
| Datensatznummer |
250118430
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| Publikation (Nr.) |
 copernicus.org/acp-14-2203-2014.pdf |
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| Zusammenfassung |
Aerosol-cloud interactions constitute a major uncertainty in future climate
predictions. This study combines 10 years of ground-based aerosol particle
measurements from two Nordic background stations (Vavihill and
Hyytiälä) with MODIS (Moderate Resolution Imaging Spectroradiometer)
satellite data of convective clouds. The merged data are used to examine how
aerosols affect cloud droplet sizes and precipitation from convective clouds
over the Nordic countries. From the satellite scenes, vertical profiles of
cloud droplet effective radius (re) are created by plotting retrieved
cloud top re against cloud top temperature for the clouds in a given
satellite scene. The profiles have been divided according to aerosol number
concentrations but also meteorological reanalysis parameters from the ECMWF
(European Centre for Medium-Range Forecasts). Furthermore, weather radar
data from the BALTEX (Baltic Sea Experiment) and precipitation data from
several ground-based meteorological measurement stations have been
investigated to determine whether aerosols affect precipitation intensity
and amount.
Small re throughout the entire cloud profiles is associated with high
aerosol number concentrations at both stations. However, aerosol number
concentrations seem to affect neither the cloud optical thickness nor the
vertical extent of the clouds in this study. Cloud profiles with no or
little precipitation have smaller droplets than those with more
precipitation. Moreover, the amount of precipitation that reaches the ground
is affected by meteorological conditions such as the vertical extent of the
clouds, the atmospheric instability and the relative humidity in the lower
atmosphere rather than the aerosol number concentration. However, lower
precipitation rates are associated with higher aerosol number concentrations
for clouds with similar vertical extent. The combination of these
ground-based and remote-sensing datasets provides a unique long-term study
of the effects of aerosols on convective clouds over the Nordic countries. |
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