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Titel |
Stable water isotopes in the coupled atmosphere–land surface model ECHAM5-JSBACH |
VerfasserIn |
B. Haese, M. Werner, G. Lohmann |
Medientyp |
Artikel
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Sprache |
Englisch
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ISSN |
1991-959X
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Digitales Dokument |
URL |
Erschienen |
In: Geoscientific Model Development ; 6, no. 5 ; Nr. 6, no. 5 (2013-09-10), S.1463-1480 |
Datensatznummer |
250084987
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Publikation (Nr.) |
copernicus.org/gmd-6-1463-2013.pdf |
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Zusammenfassung |
In this study we present first results of a new model development,
ECHAM5-JSBACH-wiso, where we have incorporated the stable water isotopes
H218O and HDO as tracers in the hydrological cycle of the coupled
atmosphere–land surface model ECHAM5-JSBACH. The ECHAM5-JSBACH-wiso model
was run under present-day climate conditions at two different resolutions
(T31L19, T63L31). A comparison between ECHAM5-JSBACH-wiso and ECHAM5-wiso
shows that the coupling has a strong impact on the simulated temperature and
soil wetness. Caused by these changes of temperature and the hydrological
cycle, the δ18O in precipitation also shows variations from
−4‰ up to 4‰. One of the strongest anomalies is shown
over northeast Asia where, due to an increase of temperature, the
δ18O in precipitation increases as well. In order to analyze
the sensitivity of the fractionation processes over land, we compare a set of
simulations with various implementations of these processes over the land
surface. The simulations allow us to distinguish between no fractionation,
fractionation included in the evaporation flux (from bare soil) and also
fractionation included in both evaporation and transpiration (from water
transport through plants) fluxes. While the isotopic composition of the soil
water may change for δ18O by up to +8&permil:, the
simulated δ18O in precipitation shows only slight differences
on the order of ±1‰. The simulated isotopic composition of
precipitation fits well with the available observations from the GNIP (Global
Network of Isotopes in Precipitation) database. |
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