Dynamics of N Resonantly Interacting Baroclinic Waves

Arthur Z. Loesch State University of New York at Albany, Albany, N. Y. 12222

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Alan Domaracki State University of New York at Albany, Albany, N. Y. 12222

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Abstract

Dynamics of N ≥ 5 resonantly interacting baroclinic waves, one of which is marginally unstable and the remaining N − 1 are neutral, are investigated in a quasi-geostrophic inviscid two-layer model. Numerical solutions of equations governing the long time evolution of the wave amplitudes predominantly yield a separation between instability and interactions in period and characteristics of amplitude oscillations. The instability is felt on a longer time scale and via the marginal wave. For certain choices of initial conditions and/or neutral waves the separation breaks down in favor of one of the following. (i) resonant-like behavior of all amplitudes, (ii) a multi-time scale evolution of the amplitudes, or (iii) a very long-period, complex finestructure evolution of the individual amplitudes. The strongest energy exchange between the wave field and the mean field occurs whenever the separation takes place.

Abstract

Dynamics of N ≥ 5 resonantly interacting baroclinic waves, one of which is marginally unstable and the remaining N − 1 are neutral, are investigated in a quasi-geostrophic inviscid two-layer model. Numerical solutions of equations governing the long time evolution of the wave amplitudes predominantly yield a separation between instability and interactions in period and characteristics of amplitude oscillations. The instability is felt on a longer time scale and via the marginal wave. For certain choices of initial conditions and/or neutral waves the separation breaks down in favor of one of the following. (i) resonant-like behavior of all amplitudes, (ii) a multi-time scale evolution of the amplitudes, or (iii) a very long-period, complex finestructure evolution of the individual amplitudes. The strongest energy exchange between the wave field and the mean field occurs whenever the separation takes place.

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