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Titel |
Changes in ventilation of the Mediterranean Sea during the past 25 year |
VerfasserIn |
A. Schneider, T. Tanhua, W. Roether, R. Steinfeldt |
Medientyp |
Artikel
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Sprache |
Englisch
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ISSN |
1812-0784
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Digitales Dokument |
URL |
Erschienen |
In: Ocean Science ; 10, no. 1 ; Nr. 10, no. 1 (2014-01-27), S.1-16 |
Datensatznummer |
250116919
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Publikation (Nr.) |
copernicus.org/os-10-1-2014.pdf |
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Zusammenfassung |
Significant changes in the overturning circulation of the Mediterranean Sea
has been observed during the last few decades, the most prominent phenomena
being the Eastern Mediterranean Transient (EMT) in the early 1990s and the
Western Mediterranean Transition (WMT) during the mid-2000s. During both of
these events unusually large amounts of deep water were formed, and in the
case of the EMT, the deep water formation area shifted from the Adriatic to
the Aegean Sea. Here we synthesize a unique collection of transient tracer
(CFC-12, SF6 and tritium) data from nine cruises conducted between 1987
and 2011 and use these data to determine temporal variability of
Mediterranean ventilation. We also discuss biases and technical problems with
transient tracer-based ages arising from their different input histories over
time; particularly in the case of time-dependent ventilation.
We observe a period of low ventilation in the deep eastern (Levantine) basin
after it was ventilated by the EMT so that the age of the deep water is
increasing with time. In the Ionian Sea, on the other hand, we see evidence
of increased ventilation after year 2001, indicating the restarted deep water
formation in the Adriatic Sea. This is also reflected in the increasing age
of the Cretan Sea deep water and decreasing age of Adriatic Sea deep water
since the end of the 1980s. In the western Mediterranean deep basin we see
the massive input of recently ventilated waters during the WMT. This signal
is not yet apparent in the Tyrrhenian Sea, where the ventilation seems to be
fairly constant since the EMT. Also the western Alboran Sea does not show any
temporal trends in ventilation. |
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