Energy transfers in internal gravity wave spectra

Dirk.Olbers [ at ]


The kinetic equation for non-linear wave-wave interactions for empirical wave energy spectra is discussed in Lagrangian and Eulerian form evaluated numerically. Wave spectrum parameters, such as bandwidth, spectral slope, and Coriolis frequency $f$, are varied as well as the spectral resolution. In agreement with previous studies we find in all cases indication of a forward energy cascade towards smaller vertical and horizontal wavelengths. Forcing is predominantly required in the frequency range between 2$f$ and 3$f$. Forcing by baroclinic tides or near inertial waves thus need to propagation into the appropriate latitudinal range. While the mechanism of the energy transfer differs partly from findings of previous studies, parameterisations for the dissipation of gravity waves used for observational estimates of turbulent mixing coefficients and for internal wave models agree surprisingly well with the numerical evaluation of the energy transfers. We suggest a simple dependency of dissipation rates on spectral slope which can in principle be used to improve observational estimates.

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Conference (Talk)
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Scales and scaling cascades in geophysical systems, 04 Apr 2018 - 01 Jan 1970, Hamburg.
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Olbers, D. (2018): Energy transfers in internal gravity wave spectra , Scales and scaling cascades in geophysical systems, Hamburg, 4 April 2018 - unspecified .


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