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| Titel |
Testing the limits of quasi-geostrophic theory |
| VerfasserIn |
Paul Williams, Peter Read, Thomas Haine |
| 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 |
250052684
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| Zusammenfassung |
| We compare laboratory observations of equilibrated baroclinic waves in the rotating
two-layer annulus, with numerical simulations from a quasi-geostrophic model. The
laboratory experiments lie well outside the quasi-geostrophic regime: the Rossby number
reaches unity; the depth-to-width aspect ratio is large; and the fluid contains ageostrophic
inertia–gravity waves.
Despite being formally inapplicable, the quasi-geostrophic model captures the laboratory
flows reasonably well. The model displays several systematic biases compared to the
laboratory, in terms of the wavenumber regime diagram, the wave amplitudes, and the wave
speeds. The biases are shown to be consequences of the model’s treatment of Ekman and
Stewartson boundary layers and its neglect of interfacial surface tension. Consequently, the
biases may be explained without invoking the dynamical effects of the moderate Rossby
number, large aspect ratio, or inertia–gravity waves.
We conclude that quasi-geostrophic theory appears to continue to apply well outside its
formal bounds.
Reference
Williams, Read and Haine (2010) Testing the limits of quasi-geostrophic theory:
application to observed laboratory flows outside the quasi-geostrophic regime. Journal of
Fluid Mechanics 649, pp 187–203. http://dx.doi.org/10.1017/S0022112009993405 |
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