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| Titel |
Tidal variability of the motion in the Strait of Otranto |
| VerfasserIn |
L. Ursella, V. Kovačević, M. Gačić |
| 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 (2014-02-13), S.49-67 |
| Datensatznummer |
250116923
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| Publikation (Nr.) |
 copernicus.org/os-10-49-2014.pdf |
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| Zusammenfassung |
| Various current data, collected in the Strait of Otranto during the period
1994–2007, have been analysed with the aim of describing the characteristics
of the tidal motions and their contribution to the total flow variance. The
principal tidal constituents in the area were the semi-diurnal (M2) and the
diurnal (K1), with the latter one predominant. The total flow was, in
general, more energetic along the flanks than in the middle of the strait.
Specifically, it was most energetic over the western shelf and in the upper
layer along the eastern flank. In spite of the generally low velocities (a
few cm s−1) of the principal tidal constituents, the tidal variance has
a pattern similar to that of the total flow variance, that is, it was large
over the western shelf and low in the middle. The proportion of non-tidal
(comprising the inertial and sub-inertial low-frequency bands) to tidal flow
variances was quite variable in both time and space. The low-frequency
motions dominated over the tidal and inertial ones in the eastern portion of
the strait during the major part of the year, particularly in the upper and
intermediate layers. In the deep, near-bottom layer the variance was evenly
distributed between the low frequency, diurnal and semi-diurnal bands. An
exception was observed near the western shelf break during the summer season
when the contribution of the tidal signal to the total variance reached
77%. This high contribution was mainly due to the intensification of the
diurnal signal at that location at both upper and bottom current records
(velocities of about 10 cm s−1). Local wind and sea level data were
analysed and compared with the flow to find the possible origin of this
diurnal intensification. Having excluded the sea-breeze impact on the
intensification of the diurnal tidal signal, the most likely cause remains
the generation of the topographically trapped internal waves and the diurnal
resonance in the tidal response. These waves were sometimes generated by the
barotropic tidal signal in the presence of summer stratification and the
strong bottom slope. This phenomenon may stimulate diapycnal mixing during
the stratified season and enhance ventilation of the near-bottom layers. |
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