Influence of forced near-inertial motion on the kinetic energy of a nearly-geostrophic flow

The effect of forced near-inertial motion on the kinetic energy budget of a turbulent, geostrophic background flow is examined using a primitive equation ocean circulation model. Balanced and unbalanced parts of the flow are taken to be equivalent to lowand high-passed filtered versions of the model fields, and the Reynolds stresses associated with the high-passed, predominantly near-inertial part of the flow are found to extract low frequency kinetic energy. Transfer spectra show that this transfer occurs at wavenumbers close to the deformation wavenumber, ie, at mesoscale wavenumbers. Whether or not this “advective sink” results in a reduction of low frequency kinetic energy is found to be sensitive to model resolution and to a pressure work term which is peaked a higher horizontal wavenumber and transfers energy between the balanced potential and kinetic energy pools.