 |
| Titel |
Simulated oxygen isotopes in cave drip water and speleothem calcite in European caves |
| VerfasserIn |
A. Wackerbarth, P. M. Langebroek, M. Werner, G. Lohmann, S. Riechelmann, A. Borsato, A. Mangini |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
1814-9324
|
| Digitales Dokument |
URL |
| Erschienen |
In: Climate of the Past ; 8, no. 6 ; Nr. 8, no. 6 (2012-11-05), S.1781-1799 |
| Datensatznummer |
250005969
|
| Publikation (Nr.) |
 copernicus.org/cp-8-1781-2012.pdf |
|
|
|
|
|
| Zusammenfassung |
Interpreting stable oxygen isotope (δ18O) records from stalagmites
is still one of the complex tasks in speleothem research. Here, we present a
novel model-based approach, where we force a model describing the processes
and modifications of δ18O from rain water to speleothem calcite
(Oxygen isotope Drip water and Stalagmite Model – ODSM) with the results of
a state-of-the-art atmospheric general circulation model enhanced by explicit
isotope diagnostics (ECHAM5-wiso). The approach is neither climate nor
cave-specific and allows an integrated assessment of the influence of
different varying climate variables, e.g. temperature and precipitation
amount, on the isotopic composition of drip water and speleothem calcite.
First, we apply and evaluate this new approach under present-day climate
conditions using observational data from seven caves from different
geographical regions in Europe. Each of these caves provides measured
δ18O values of drip water and speleothem calcite to which we
compare our simulated isotope values. For six of the seven caves modeled
δ18O values of drip water and speleothem calcite are in good
agreement with observed values. The mismatch of the remaining caves might be
caused by the complexity of the cave system, beyond the parameterizations
included in our cave model.
We then examine the response of the cave system to mid-Holocene (6000 yr
before present, 6 ka) climate conditions by forcing the ODSM with
ECHAM5-wiso results from 6 ka simulations. For a set of twelve European
caves, we compare the modeled mid-Holocene-to-modern difference in speleothem
calcite δ18O to available measurements. We show that the general
European changes are simulated well. However, local discrepancies are found,
and might be explained either by a too low model resolution, complex local
soil-atmosphere interactions affecting evapotranspiration or by cave specific
factors such as non-equilibrium fractionation processes.
The mid-Holocene experiment pronounces the potential of the presented
approach to analyse δ18O variations on a spatially large (regional
to global) scale. Modelled as well as measured European δ18O values
of stalagmite samples suggest the presence of a strong, positive mode of the
North Atlantic Oscillation at 6 ka before present, which is supported by the
respective modelled climate parameters. |
| |
|
| Teil von |
|
|
|
|
|
|
|
|