Stable water isotopologue ratios in fog and cloud droplets are not size-dependent
Abstract
In this work, we present the first observations of stable water isotopologue ratios incloud droplets of different sizes collected simultaneously. We address the questionwhether the isotope ratio of droplets in a cloud varies as a function of droplet size. Sam-ples were collected from a ground intercepted cloud (=fog) during the Hill Cap Cloud Thuringia 2010 campaign (HCCT-2010) using a three-stage Caltech Active StrandCloud water Collector (CASCC). An instrument test revealed that no artificial isotopicfractionation occurs during sample collection with the CASCC. Furthermore, we couldexperimentally confirm the hypothesis that theδvalues of cloud droplets of the rele-vant 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, atthe dissolution period of the cloud differences in isotope ratios of the different dropletsizes tended to be larger. This is likely to result from the cloud’s heterogeneity, implyingthat larger and smaller cloud droplets have been collected at different moments in time,delivering isotope ratios from different collection times. Show more
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https://doi.org/10.3929/ethz-b-000060293Publication status
publishedExternal links
Journal / series
Atmospheric Chemistry and PhysicsVolume
Pages / Article No.
Publisher
CopernicusOrganisational unit
03648 - Buchmann, Nina / Buchmann, Nina
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