Near-Inertial Energy Propagation from the Mixed Layer: Theoretical Considerations

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Abstract
Wind-generated inertial currents can radiate from the mixed layer as horizontally and vertically propagating new-inertial internal gravity waves. To study the timescale of the decay of mixed layer energy and the magnitude of the energy transfer to the ocean below, the authors developed a numerical, linear model on a β plane, using baroclinic modes to describe the velocity field. The model is unforced-wave propagation is initiated by specifying the mixed layer currents that would he generated by a moving atmospheric front. The numerical results are interpreted using concepts of modal interference and modal departure that can be evaluated analytically, thereby permitting predictions Of some features of wave field evolution without the need to run the numerical model. The energy exchange with the pycnocline and deep ocean is explored as a function of the propagation speed and direction of the front, the horizontal extent of the storm, and the background stratification. The timescale of energy transf... Abstract Wind-generated inertial currents can radiate from the mixed layer as horizontally and vertically propagating new-inertial internal gravity waves. To study the timescale of the decay of mixed layer energy and the magnitude of the energy transfer to the ocean below, the authors developed a numerical, linear model on a β plane, using baroclinic modes to describe the velocity field. The model is unforced-wave propagation is initiated by specifying the mixed layer currents that would he generated by a moving atmospheric front. The numerical results are interpreted using concepts of modal interference and modal departure that can be evaluated analytically, thereby permitting predictions Of some features of wave field evolution without the need to run the numerical model. The energy exchange with the pycnocline and deep ocean is explored as a function of the propagation speed and direction of the front, the horizontal extent of the storm, and the background stratification. The timescale of energy transf...
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