On Forced Barotropic Vorticity Oscillations

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  • 1 Scripps Institution of Oceanography, University of California at San Diego, La Jolla, California
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Abstract

Forced, nonresonant barotropic response at low frequencies (ω ≪ f) and large scales (Lf/β) can be written in terms of a streamfunction, which is similar to the quasigeostrophically derived streamfunction. However, the “nearly equilibrium” forced vorticity equation is valid on the planetary length scale and is influenced not only by the vortex stretching induced by the driving mechanism (tides, atmospheric pressure, or Ekman-pumping displacement) but also by β coupling to the divergent velocity field of the nearly equilibrium response. A similar result follows for topographic coupling, albeit on the topographic length scale.

Abstract

Forced, nonresonant barotropic response at low frequencies (ω ≪ f) and large scales (Lf/β) can be written in terms of a streamfunction, which is similar to the quasigeostrophically derived streamfunction. However, the “nearly equilibrium” forced vorticity equation is valid on the planetary length scale and is influenced not only by the vortex stretching induced by the driving mechanism (tides, atmospheric pressure, or Ekman-pumping displacement) but also by β coupling to the divergent velocity field of the nearly equilibrium response. A similar result follows for topographic coupling, albeit on the topographic length scale.

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