Inertial Oscillations due to a Moving Front

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  • 1 Oceanographic Center, Nova University, Dania, FL 33004
  • | 2 Institute of Ocean Science, Sidney, B.C. V8L 4B2, Canada
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Abstract

A solution for a concentrated line front translating at speed U is given. It is shown that the frequency is near-inertial if Uc1, where c1 is the long internal wave speed of the first baroclinic mode. Each more has a charactristic frequency ωn associated with it. The spectra contain a near-inertial primary peak, composed of the higher modes, whose blue shift increases with depth. They also contain secondary peaks at higher internal wave frequencies if U is only slightly larger than c1. The flow field is intermittent, and involves a continuous interchange of energy between the surface layer and the stratified interior. The dominant period of this intermittency is the beating period of the first mode with a purely inertial oscillation. Short periods of apparent subinertial motion are also generated. Several features of the solution are in agreement with observations.

Abstract

A solution for a concentrated line front translating at speed U is given. It is shown that the frequency is near-inertial if Uc1, where c1 is the long internal wave speed of the first baroclinic mode. Each more has a charactristic frequency ωn associated with it. The spectra contain a near-inertial primary peak, composed of the higher modes, whose blue shift increases with depth. They also contain secondary peaks at higher internal wave frequencies if U is only slightly larger than c1. The flow field is intermittent, and involves a continuous interchange of energy between the surface layer and the stratified interior. The dominant period of this intermittency is the beating period of the first mode with a purely inertial oscillation. Short periods of apparent subinertial motion are also generated. Several features of the solution are in agreement with observations.

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