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Stable water isotopologue ratios in fog and cloud droplets of liquid clouds are not size-dependent

Atmospheric Chemistry and Physics

By:
, , , , , , , , , , , ,
DOI: 10.5194/acp-12-9855-2012

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Abstract

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.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Stable water isotopologue ratios in fog and cloud droplets of liquid clouds are not size-dependent
Series title:
Atmospheric Chemistry and Physics
DOI:
10.5194/acp-12-9855-2012
Volume
12
Year Published:
2012
Language:
English
Publisher:
European Geosciences Union
Contributing office(s):
National Research Program - Eastern Branch
Description:
9 p.
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
First page:
9855
Last page:
9863
Number of Pages:
9
Country:
United States