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| Titel |
Stratified inertial subrange as inferred from in situ measurements in the bottom boundary layer of Rockall Channel |
| VerfasserIn |
Pascale Bouruet-Aubertot, Hans van Haren, Pascale Lelong |
| Konferenz |
EGU General Assembly 2011
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 13 (2011) |
| Datensatznummer |
250055619
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| Zusammenfassung |
| Deep-ocean high resolution moored temperature data are analyzed with a focus on
super-buoyant frequencies. A local Taylor hypothesis based on the horizontal velocity
averaged over two hours is used to infer horizontal wavenumber spectra of temperature
variance. The inertial subrange extends over fairly low horizontal wavenumbers, typically
within [2x10-3;2x10-1]cpm. It is therefore interpreted as a stratified inertial subrange
for most of this wavenumber interval while in some cases the convective inertial
subrange is resolved as well. Kinetic energy dissipation rate, ε, is inferred using
theoretical expressions for the stratified inertial subrange. A wide range of values within
[10-9,4x10-7]m2s-3 is obtained for time periods either dominated by semi-diurnal tides or
by significant sub-inertial variability. A scaling for ε that depends on the potential
energy within the IGW frequency band, PEIGW, and the buoyancy frequency, N, is
proposed for these two cases. When semi-diurnal tides dominate, ε -ă (PEIGWN)3-2,
whereas ε -ă PEIGWN in the presence of significant sub-inertial variability. This
result is obtained for energy levels ranging from [1 - 30] times the Garrett-Munk
energy level and is in contrast with classical fine-scale parameterization in which
ε ~ PEIGW 2 that applies far from energy sources. The specificities of the stratified
bottom boundary layer, namely a weak stratification, may account for this difference. |
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