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| Titel |
Modelling of stable water isotopes in Central Europe with COSMOiso |
| VerfasserIn |
Emanuel Christner, Stephan Pfahl, Gerd Schädler |
| Konferenz |
EGU General Assembly 2016
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 18 (2016) |
| Datensatznummer |
250133619
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| Publikation (Nr.) |
 EGU/EGU2016-14249.pdf |
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| Zusammenfassung |
| Atmospheric water in form of vapor or clouds is responsible for ∼75 % of the
natural greenhouse effect and carries huge amounts of latent heat. For this reason, a
best possible description of the hydrological cycle is a prerequisite for reliable
climate modelling. As the stable isotopes H216O, H218O and HDO differ in vapor
pressure, they are fractionated during phase changes and contain information about
the formation of precipitation, evaporation from the ground, etc. Therefore, the
isotopic composition of atmospheric water is an useful tracer to test and improve our
understanding of the extremely complex and variable hydrological cycle in Earth’s
atmosphere.
Within the project PalMod the isotope-enabled limited-area model COSMOiso will
be used for high-resolution isotope simulations of paleo-climates. For validation
with modern observations we compare 12 years of modelled isotope ratios from
Central Europe to observations of the Global Network of Isotopes in Precipitation
(GNIP) and to observations of isotope ratios of water vapor at different locations in
Germany.
We find a good agreement of modelled and observed isotope ratios in summer.
In winter, we observe a systematic overestimation of modelled isotope ratios in
precipitation and low-level water vapor. We relate those differences to specific circulation
regimes with predominantly easterly moisture transport and the corresponding strong
dependence of modelled isotope ratios on lateral boundary data. Furthermore, we
investigate the dependence of modelled isotope ratios in winter on the type of isotope
fractionation during surface evaporation at skin temperatures close to the freezing point. |
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