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Titel |
Tracers confirm downward mixing of Tyrrhenian Sea upper waters associated with the Eastern Mediterranean Transient |
VerfasserIn |
W. Roether, J. E. Lupton |
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 ; 7, no. 1 ; Nr. 7, no. 1 (2011-01-28), S.91-99 |
Datensatznummer |
250004433
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Publikation (Nr.) |
copernicus.org/os-7-91-2011.pdf |
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Zusammenfassung |
Observations of tritium and 3He in the Tyrrhenian Sea, 1987–2009,
confirm the enhanced vertical mixing of intermediate waters into the deep
waters that has been noted and associated with the Eastern Mediterranean
Transient in previous studies. Our evidence for the mixing rests on
increasing tracer concentrations in the Tyrrhenian deep waters, accompanied
by decreases in the upper waters, which are supplied from the Eastern
Mediterranean. The downward transfer is particularly evident between 1987
and 1997. Later on, information partly rests on increasing tritium-3He
ages; here we correct the observed 3He for contributions released from
the ocean floor. The Tyrrhenian tracer distributions are fully compatible
with data upstream of the Sicily Strait and in the Western Mediterranean.
The tracer data show that mixing reached to the bottom and confirm a
cyclonic nature of the deep water circulation in the Tyrrhenian. They
furthermore indicate that horizontal homogenization of the deep waters
occurs on a time scale of roughly 5 years. Various features point to a
reduced impact of Western Mediterranean Deep Water (WMDW) in the Tyrrhenian
during the enhanced-mixing period. This is an important finding because it
implies less upward mixing of WMDW, which has been named a major process to
enable the WMDW to leave the Mediterranean via the Gibraltar Strait. On the
other hand, the TDW outflow for several years represented a major influx of
enhanced salinity and density waters into the deep-water range of the
Western Mediterranean. |
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