CYCLO-GEOSTROPHIC ADJUSTMENT AND BAROCLINIC INSTABILITY FOR REAL TWO-LAYER VORTICES
(thesis Emmanuelle THIVOLLE-CAZAT)
Experimental setup |
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Photo |
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1 Inertial oscillations
At t=0, the cylinder is removed. The radial pressure gradient drives the fluid in the displaced volume either outwards or inwards. Due to the Coriolis force, the fluid from the displaced volume rotates anticyclonically or cyclonically. Because the lower fluid is deeper, there is a weaker return flow, inwards or outwards. These return flows lead to cyclonic and anticyclonic flows in the lower layer respectively. During start up phase (~ 2 inertial periods), the vortex exhibits radial inertial oscillations which subsequently cease. |
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View from above with particles illuminated by the lasersheet |
Vertical view with fluoresceine (movie) |
t = 0 s t =16s t =28s |
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2 Baroclinic instability
| Depending on the external parameters, the vortex will remain stable or break into various unstable modes | |
Top
view of vorticity (movies) |
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Upper layer
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Lower layer
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