Drivers of δ2H variations in an idealized extratropical cyclone

Abstract Numerical model simulations of stable water isotopes help to improve our understanding of the complex processes driving isotopic variability in atmospheric moisture. We use the isotope‐enabled Consortium for Small‐Scale Modelling (COSMO) model to study the governing mechanisms of δ2H variat...

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Bibliographic Details
Main Authors: Marina Dütsch, Stephan Pfahl, Heini Wernli
Format: Article
Language:English
Published: Wiley 2016-05-01
Series:Geophysical Research Letters
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Online Access:https://doi.org/10.1002/2016GL068600
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Summary:Abstract Numerical model simulations of stable water isotopes help to improve our understanding of the complex processes driving isotopic variability in atmospheric moisture. We use the isotope‐enabled Consortium for Small‐Scale Modelling (COSMO) model to study the governing mechanisms of δ2H variations in an idealized extratropical cyclone. A set of experiments with differing initial conditions of δ2H in vapor and partly deactivated isotopic fractionation allows us to quantify the relative roles of cloud fractionation and vertical and horizontal advection for the simulated δ2H signals associated with the cyclone and fronts. Horizontal transport determines the large‐scale pattern of δ2H in both vapor and precipitation, while fractionation and vertical transport are more important on a smaller scale, near the fronts. During the passage of the cold front fractionation leads to a V‐shaped trend of δ2H in precipitation and vapor, which is, for vapor, superimposed on a gradual decrease caused by the arrival of colder air masses.
ISSN:0094-8276
1944-8007