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| Titel |
Modelling Mediterranean Climate for mid and early Holocene Time Slices |
| VerfasserIn |
U. Mikolajewicz, F. Adloff |
| Konferenz |
EGU General Assembly 2009
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 11 (2009) |
| Datensatznummer |
250027447
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| Zusammenfassung |
| During the early Holocene, the Mediterranean circulation has undergone big changes. These
changes are reflected in the occurrence of organic-rich marine sediment layers (sapropels) in
the eastern Mediterranean, which indicate the presence of oxygen depleted deep
waters.
The relative isolation of the basin together with a good coverage of available proxy data
make this region an ideal testbed for modelling past climate changes. The work presented
here is a first step towards elucidating the mechanisms responsible for the formation of the
sapropels.
A regional version of the ocean general circulation model MPIOM has been set up for the
Mediterranean. This model was forced with atmospheric data derived from quasi-equilibrium
time slice simulations with the coupled atmosphere-ocean-dynamical vegetation model
ECHAM5/MPIOM/LPJ. Time slices available are 6000 and 9000 years before present. The
model derived river-runoff and ocean hydrography were used as additional forcings,
the latter used as boundary condition at the Atlantic margin of the regional ocean
model.
The model has been integrated for more than 100 years starting from climatology. The
effect of insolation changes on Mediterranean ocean climate is analyzed. Due to the limited
length of the simulations, only the upper few hundred meters are in equilibrium with the
implied forcing. The increased runoff from the Nile due to the enhanced African monsoon
leads to a substantial reduction of the salinity in the Levantine basin. The amplified
seasonal cycle with reduced incoming short-wave radiation in winter leads to a
general cooling of the upper few hundred meters of the ocean. The effect of the
enhanced summer insolation is restricted to the upper ocean. The amplitude of the
seasonal cycle of SST is larger. The model results are compared to available proxy
data. |
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