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Wavenumber selection and hysteresis in nonlinear baroclinic flowWavenumber transition and hysteresis in a highly unstable baroclinic flow are investigated using a high-resolution spectral numerical model. As the flow becomes more supercritical, the dominant wave gradually shifts from the most unstable wave predicted by the linear theory to a longer wave with a larger time-averaged amplitude, while the rectified mean flow attains a stronger shear at the center of the channel. The numerical results display a complex hysteresis behavior, which occurs not only between the states of different dominant wavenumbers, but also between the states of identical dominant wavenumber but of different dynamic characteristics. In a certain parameter range three stable states, each with different dominant wavenumber, are possible, and in another parameter range four stable states are possible, among them three stable states with an identical dominant wave. The numerical results suggest that a multiple weather regime exists even without external forcing in which the flow aperiodically varies between two distinct behaviors. The effects of stable higher harmonics are assessed and it is found that their presence contributes not only to the better approximation of the model solutions but also to the selection of the final equilibrium state, due to the chaotic nature of the initial transient period.
Document ID
Document Type
Reprint (Version printed in journal)
Chou, Shih-Hung
(NASA Marshall Space Flight Center Huntsville, AL, United States)
Date Acquired
September 6, 2013
Publication Date
September 15, 1995
Subject Category
Fluid Mechanics And Heat Transfer
Report/Patent Number
NAS 1.15:111211
Accession Number
Distribution Limits
Public Use Permitted.
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