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Titel |
Comparison of calculated internal tide energy flux with microstructure measurements |
VerfasserIn |
Saeed Falahat, Jonas Nycander |
Konferenz |
EGU General Assembly 2013
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Medientyp |
Artikel
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Sprache |
Englisch
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Digitales Dokument |
PDF |
Erschienen |
In: GRA - Volume 15 (2013) |
Datensatznummer |
250080815
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Zusammenfassung |
A comparison of the model-derived vertical energy flux from the internal tide with
micro-structure measurements is undertaken. The latter data set originates from two field
surveys during the Brazil Basin Tracer Release experiment (BBTRE1, BBTRE2) as well as
from a third field cruise of the LArval Dispersal along the Deep East-Pacific Rise project
(LADDER3). The model for estimating the time-dependent vertical energy flux is
based on linear wave theory, and takes into account the the finite depth of the ocean,
the spatial variations of the bathymetry and the spatio-temporal variations of the
barotropic tide. The temporal average of the vertical energy flux over a limited
period (a few days) immediately before the observational time is compared with the
depth-integrated observed energy dissipation rate. A rather good correlation was
found between the theoretical predictions and the microstructure data from the
BBTRE2 field survey, while the comparison made for the BBTRE1 survey yields a
low correlation, The model-based estimates of the vertical energy flux are of the
correct order of magnitude, and imply that about one third of the internal wave
energy dissipates locally. In the case of LADDER3, the comparison between the
observations and the model predictions shows a significant correlation, whereas the
modelled energy flux is much higher than the observed dissipation, implying a very low
dissipation efficiency. A possible explanation is that the sharp topography at the
East-Pacific Rise consists of a few isolated seamounts, which should mean that the general
background level of internal wave energy is low. If nonlinear wave interaction is
essential for wave dissipation, the wave dissipation should then be less local in
this region than in the eastern Brazil Basin, with very extended rough topography. |
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