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| Titel |
Seasonal and inter-annual temperature variability in the bottom waters over the western Black Sea shelf |
| VerfasserIn |
G. I. Shapiro, F. Wobus, D. L. Aleynik |
| 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. 5 ; Nr. 7, no. 5 (2011-09-22), S.585-596 |
| Datensatznummer |
250004800
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| Publikation (Nr.) |
 copernicus.org/os-7-585-2011.pdf |
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| Zusammenfassung |
| Long-term changes in the state of the Bottom Shelf Water (BSW) on the
Western shelf of the Black Sea are assessed using analysis of intra-seasonal
and inter-annual temperature variations. For the purpose of this study the
BSW is defined as such shelf water mass between the seabed and the upper
mixed layer (bounded by the σθ = 14.2 isopycnal) which has
limited ability to mix vertically with oxygen-rich surface waters during the
warm season due to formation of a seasonal pycnocline. A long-term time
series of temperature anomalies in the BSW is constructed from in-situ
observations taken over the 2nd half of the 20th century. The BSW
is shown to occupy nearly half of the shelf area during the summer
stratification period (May–November).The results reveal a warm phase in the
1960s/70s, followed by a cold phase between 1985 and 1995 and a further
warming after 1995. The transition between the warm and cold periods
coincides with a regime shift in the Black Sea ecosystem. While it was
confirmed that the memory of winter convection is well preserved over the
following months in the deep sea, the signal of winter cooling in the BSW
significantly reduces during the warm season. The potential of the BSW to
ventilate horizontally during the warm season with the deep-sea waters is
assessed using isopycnic analysis of temperature variations. It is shown
that temperature in the BSW is stronger correlated with the temperature of
Cold Intermediate Waters (CIW) in the deep sea than with the severity of the
previous winters, thus indicating that the isopycnal exchanges with the deep
sea are more important for inter-annual/inter-decadal variability of the
BSW on the western Black Sea shelf than effects of winter convection on the
shelf itself. |
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