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The effect of topography on the evolution of unstable disturbances in a baroclinic atmosphereA two layer spectral quasi-geostrophic model is used to simulate the effects of topography on the equilibria, their stability, and the long term evolution of incipient unstable waves. The flow is forced by latitudinally dependent radiative heating. Dissipation is in the form of Rayleigh friction. An analytical solution is found for the propagating finite amplitude waves which result from baroclinic instability of the zonal winds when topography is absent. The appearance of this solution for wavelengths just longer than the Rossby radius of deformation and disappearance of ultra-long wavelengths is interpreted in terms of the Hopf bifurcation theory. Simple dynamic and thermodynamic criteria for the existence of periodic Rossby solutions are presented. A Floquet stability analysis shows that the waves are neutral. The nature of the form drag instability of high index equilibria is investigated. The proximity of the equilibrium shear to a resonant value is essential for the instability, provided the equilibrium occurs at a slightly stronger shear than resonance.
Document ID
Document Type
Clark, J. H. E. (Pennsylvania State Univ. University Park, PA, United States)
Date Acquired
August 12, 2013
Publication Date
May 1, 1985
Publication Information
Publication: The Util. of Satellite Data and Dyn. in Understanding and Predicting Global Weather Phenomena
Subject Category
Distribution Limits
Work of the US Gov. Public Use Permitted.
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