An experimental study of regime transitions in a differentially heated baroclinic annulus with flat and sloping bottom topographies
A series of laboratory experiments has been carried out in a thermally driven rotating annulus to study the onset of baroclinic instability, using horizontal and uniformly sloping bottom topographies. Different wave flow regimes have been identified and their phase boundaries – expressed in terms of...
| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2014-02-01
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| Series: | Nonlinear Processes in Geophysics |
| Online Access: | http://www.nonlin-processes-geophys.net/21/237/2014/npg-21-237-2014.pdf |
| Summary: | A series of laboratory experiments has been carried out in a thermally driven
rotating annulus to study the onset of baroclinic instability, using
horizontal and uniformly sloping bottom topographies. Different wave flow
regimes have been identified and their phase boundaries – expressed in terms
of appropriate non-dimensional parameters – have been compared to the recent
numerical linear stability analysis of von Larcher et al. (2013). In the flat
bottom case, the numerically predicted alignment of the boundary between the
axisymmetric and the regular wave flow regime was found to be consistent with
the experimental results. However, once the sloping bottom end wall was
introduced, the detected behaviour was qualitatively different from that of
the simulations. This disagreement is thought to be the consequence of
nonlinear wave–wave interactions that could not be resolved in the framework
of the numerical study. This argument is supported by the observed
development of interference vacillation in the runs with sloping bottom, a
mixed flow state in which baroclinic wave modes exhibiting different drift
rates and amplitudes can co-exist. |
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| ISSN: | 1023-5809 1607-7946 |