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| Titel |
Inertial instability in island wakes |
| VerfasserIn |
Ayah Lazar, Eyal Heifetz, Alexandre Stegner |
| 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 |
250046180
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| Zusammenfassung |
| Submesoscale and intense vortices are often encountered in the wakes of isolated islands.
However, unlike the standard two-dimensional Kármán street, the oceanic vortex streets are
affected by the earth’s rotation and the vertical stratification of the thermocline. Inertial
instability, which is a centrifugal instability mechanism in the presence of the Coriolis
force, is a destructive mechanism that acts selectively on anticyclones with strong
vorticities. Here we present preliminary results suggesting that this instability may be an
additional, and somewhat overlooked, mechanism for three-dimensional mixing in
island wakes, supplying nutrient-rich waters from the base of the photic zone, and
creating localized blooms. In contrast, the stratification has a stabilizing effect,
which limits the mixing, and may lead to stable anticyclones with finite relative
vorticity.
We use linear stability analysis to define the dynamical parameters that govern the
stability, and find the parameters, which are both insensitive to different vorticity profiles
and are relatively easy to estimate from laboratory experiments and oceanic in situ
measurements. We map this parameter space, and corroborate our findings with large-scale
laboratory experiments studies, performed at the LEGI-Coriolis platform. Finally, we
compare our calculations with some published oceanic island wake case studies. |
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