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Titel |
Stable water isotopologue ratios in fog and cloud droplets of liquid clouds are not size-dependent |
VerfasserIn |
J. K. Spiegel, F. Aemisegger, M. Schöll, F. G. Wienhold, J. L. Collett, T. Lee, D. Pinxteren, S. Mertes, A. Tilgner, H. Herrmann, R. A. Werner, N. Buchmann, W. Eugster |
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 ; 12, no. 20 ; Nr. 12, no. 20 (2012-10-29), S.9855-9863 |
Datensatznummer |
250011539
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Publikation (Nr.) |
copernicus.org/acp-12-9855-2012.pdf |
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Zusammenfassung |
In this work, we present the first observations of stable water isotopologue
ratios in cloud droplets of different sizes collected simultaneously. We
address the question whether the isotope ratio of droplets in a liquid cloud
varies as a function of droplet size. Samples were collected from a ground
intercepted cloud (= fog) during the Hill Cap Cloud Thuringia 2010 campaign
(HCCT-2010) using a three-stage Caltech Active Strand Cloud water Collector
(CASCC). An instrument test revealed that no artificial isotopic
fractionation occurs during sample collection with the CASCC. Furthermore, we
could experimentally confirm the hypothesis that the δ values of cloud
droplets of the relevant droplet sizes (μm-range) were not
significantly different and thus can be assumed to be in isotopic equilibrium
immediately with the surrounding water vapor. However, during the dissolution
period of the cloud, when the supersaturation inside the cloud decreased and
the cloud began to clear, differences in isotope ratios of the different
droplet sizes tended to be larger. This is likely to result from the cloud's
heterogeneity, implying that larger and smaller cloud droplets have been
collected at different moments in time, delivering isotope ratios from
different collection times. |
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