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| Titel |
Strong aerosol–cloud interaction in altocumulus during updraft periods: lidar observations over central Europe |
| VerfasserIn |
J. Schmidt, A. Ansmann, J. Bühl, U. Wandinger |
| 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 ; 15, no. 18 ; Nr. 15, no. 18 (2015-09-25), S.10687-10700 |
| Datensatznummer |
250120057
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| Publikation (Nr.) |
 copernicus.org/acp-15-10687-2015.pdf |
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| Zusammenfassung |
| For the first time, a liquid-water cloud study of the aerosol–cloud-dynamics relationship, solely
based on lidar, was conducted. Twenty-nine cases of pure liquid-water
altocumulus layers were observed with a novel dual-field-of-view Raman lidar
over the polluted central European site of Leipzig, Germany, between
September 2010 and September 2012. By means of the novel Raman lidar
technique, cloud properties such as the droplet effective radius and cloud
droplet number concentration (CDNC) in the lower part of altocumulus layers
are obtained. The conventional aerosol Raman lidar technique provides the
aerosol extinction coefficient (used as aerosol proxy) below cloud base. A
collocated Doppler lidar measures the vertical velocity at cloud base and
thus updraft and downdraft occurrence. Here, we present the key results of
our statistical analysis of the 2010–2012 observations. Besides a clear
aerosol effect on cloud droplet number concentration in the lower part of the
altocumulus layers during updraft periods, turbulent mixing and entrainment
of dry air is assumed to be the main reason for the found weak correlation
between aerosol proxy and CDNC higher up in the cloud. The corresponding
aerosol–cloud interaction parameter based on changes in cloud droplet number
concentration with aerosol loading was found to be close to 0.8 at 30–70 m
above cloud base during updraft periods and below 0.4 when ignoring
vertical-wind information in the analysis. Our findings are extensively
compared with literature values and agree well with airborne observations. |
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