Articles | Volume 3, issue 3
Nonlin. Processes Geophys., 3, 150–165, 1996
https://doi.org/10.5194/npg-3-150-1996
Nonlin. Processes Geophys., 3, 150–165, 1996
https://doi.org/10.5194/npg-3-150-1996

  30 Sep 1996

30 Sep 1996

Low-order models of wave interactions in the transition to baroclinic chaos

W.-G. Früh W.-G. Früh
  • Sub-Department of Atmospheric, Oceanic, and Planetary Physics
  • Department of Physics, Clarendon Laboratory
  • Universtity of Oxford, Oxford, OX1 3PU, UK

Abstract. A hierarchy of low-order models, based on the quasi-geostrophic two-layer model, is used to investigate complex multi-mode flows. The different models were used to study distinct types of nonlinear interactions, namely wave- wave interactions through resonant triads, and zonal flow-wave interactions. The coupling strength of individual triads is estimated using a phase locking probability density function. The flow of primary interest is a strongly modulated amplitude vacillation, whose modulation is coupled to intermittent bursts of weaker wave modes. This flow was found to emerge in a discontinuous bifurcation directly from a steady wave solution. Two mechanism were found to result in this flow, one involving resonant triads, and the other involving zonal flow-wave interactions together with a strong β-effect. The results will be compared with recent laboratory experiments of multi-mode baroclinic waves in a rotating annulus of fluid subjected to a horizontal temperature gradient.

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