To investigate the formation mechanism of energy spectra of internal waves inthe oceans, direct numerical simulations are performed. The simulations arebased on the reduced dynamical equations of rotating stratified turbulence. Inthe reduced dynamical equations only wave modes are retained, and vortices andhorizontally uniform vertical shears are excluded. Despite the simplifications,our simulations reproduce some key features of oceanic internal-wave spectra:accumulation of energy at near-inertial waves and realistic frequency andhorizontal wavenumber dependencies. Furthermore, we provide evidence thatformation of the energy spectra in the inertial subrange is dominated byscale-separated interactions with the near-inertial waves. These findingssupport oceanographers' intuition that spectral energy density of internalwaves is the result of predominantly wave-wave interactions.
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