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| Titel |
Propagation and dissipation of internal tides in the Oslofjord |
| VerfasserIn |
A. Staalstrøm, E. Aas, B. Liljebladh |
| 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 ; 8, no. 4 ; Nr. 8, no. 4 (2012-07-19), S.525-543 |
| Datensatznummer |
250005748
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| Publikation (Nr.) |
 copernicus.org/os-8-525-2012.pdf |
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| Zusammenfassung |
Observations of velocity, pressure, temperature and salinity in the inner
Oslofjord have been analysed to provide new information about the
relationships between internal tides generated by tidal currents across the
Drøbak Sill and dissipation and diffusivity in the fjord.
The most energetic vertical displacement of density surfaces inside the sill
is associated with the first internal mode that has maximum amplitude around
sill depth. The amplitude of the vertical displacement around sill depth
correlates with the amplitude of the surface elevation, and, at a distance of
1 km inside the sill, the ratio between the amplitudes is 38, decreasing to
11 at a distance of 10 km. The greatest vertical displacements inside the
sill, however, are found at 40 m depth. These latter internal waves are not
associated with a first-mode internal tide, but are rather associated with
higher internal modes controlled by stratification.
The energy flux of the internal wave propagating from the Drøbak Sill
into the inner fjord on the east side of the Håøya Island is
estimated to vary in the range 155–430 kW. This is the same order of
magnitude as the estimated barotropic energy loss over the Drøbak Sill
(250 kW), but only 4–10% of the total barotropic flux. Approximately
40–70% of the internal energy flux is lost within a distance of 10 km
from the sill. The mean diffusivity below 90 m depth in this area
(~20 cm2 s−1) is more than four times higher than in the rest of the
fjord (~5 cm2 s−1 or less). |
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