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| Titel |
The response of Mediterranean thermohaline circulation to climate change: a minimal model |
| VerfasserIn |
P. Th. Meijer, H. A. Dijkstra |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1814-9324
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| Digitales Dokument |
URL |
| Erschienen |
In: Climate of the Past ; 5, no. 4 ; Nr. 5, no. 4 (2009-11-19), S.713-720 |
| Datensatznummer |
250002700
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| Publikation (Nr.) |
 copernicus.org/cp-5-713-2009.pdf |
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| Zusammenfassung |
| Physics-based understanding of the effects of paleoclimate and
paleogeography on the thermohaline circulation of the Mediterranean Sea
requires an ocean model capable of long integrations and involving a minimum
of assumptions about the atmospheric forcing. Here we examine the
sensitivity of the deep circulation in the eastern Mediterranean basin to
changes in atmospheric forcing, considered a key factor in the deposition of
organic-rich sediments (sapropels). To this extent we explore the setup of
an ocean general circulation model (MOMA) with realistic (present-day)
bathymetry and highly idealized forcing. The model proves able to
qualitatively capture some important features of the large-scale overturning
circulation, in particular for the eastern basin. The response to (i) a
reduction in the imposed meridional temperature gradient, or (ii) a
reduction in net evaporation, proves to be non-linear and, under certain
conditions, of transient nature. Consistent with previous model studies, but
now based on a minimum of assumptions, we find that a reduction in net
evaporation (such as due to an increase in freshwater input) may halt the
deep overturning circulation. The ability to perform long model integrations
allows us to add the insight that, in order to have the conditions
favourable for sapropel formation persist, we must also assume that the
vertical mixing of water properties was reduced. The "minimal" model here
presented opens the way to experiments in which one truly follows the basin
circulation into, or out of, the period of sapropel formation and where
forcing conditions are continously adjusted to the precession cycle. |
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