The processes leading to the depletion of oceanic mesoscale kinetic
energy (KE) and the energization of near-inertial internal waves are
investigated using a suite of realistically forced regional ocean
simulations. By carefully modifying the forcing fields we show that
solutions where internal waves are forced have ~25%
less mesoscale KE compared with solutions where they are not. We apply a
coarse-graining method to quantify the KE fluxes across time scales and
demonstrate that the decrease in mesoscale KE is a result of an internal
wave-induced reduction of the inverse energy cascade and an enhancement
of the forward energy cascade from sub- to super-inertial frequencies.
The integrated KE forward transfer rate in the upper ocean is equivalent
to half and a quarter of the regionally averaged near-inertial wind work
in winter and summer, respectively, with the strongest fluxes localized
at surface submesoscale fronts and filaments.