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Baroclinic instability in an eccentric annulus

Published online by Cambridge University Press:  11 April 2006

P. R. Gent  and
H. Leach
P. R. Gent
Affiliation:
Department of Oceanography, University of Southampton, England Present address: N.C.A.R. Boulder, Colorado 80303.
H. Leach
Affiliation:
Geophysical Fluid Dynamics Laboratory, Meteorological Office, Bracknell, Berkshire, England Present address: Department of Oceanography, University of Southampton.
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Abstract

A study has been made of baroclinic instability in a differentially heated, rotating fluid annulus whose channel width varies azimuthally. Both laboratory experiments and an a.nalytica1 model employing a linear normal-mode analysis have been used. The experiments show three types of flow. For slow rotation the flow is 'symmetric’, whereas at high rotation speeds baroclinic waves occur at all azimuths. At intermediate rotation speeds it is possible to have a mixed flow which is ‘symmetric’ in the narrow part but has baroclinic waves in the wide part of the annulus. This result suggested the analytical investigation of the stability of a barocIinic flow whose meridional scale varies downstream. It was found that this model also permits three possible types of flow: everywhere stable, everywhere unstable, and also a mixed flow which is locally unstable where the meridional scale is largest but locally stable where the scale is smallest.

Type
Research Article
Information
Journal of Fluid Mechanics , Volume 77 , Issue 4 , 22 October 1976 , pp. 769 - 788
Copyright
© 1976 Cambridge University Press

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