Enhancement of Mesoscale to Submesoscale Transition and the Forward Energy Cascade by High Frequency Wind Forcing

We study the effects of high frequency (HF) wind forcing on submesoscale dynamics and energy pathways in high-resolution numerical simulations of an idealized ‘Antarctic Circumpolar Current - like’ channel flow. We investigate three solutions: one forced by steady wind forcing (LFW) one forced by stochastic wind forcing (HFW) and one forced by both (LFHFW). We demonstrate that most of the HF wind work excites near inertial waves (NIWs) and that the frequency and wave number spectral slopes of the LFHFW solution are shallower than the LFW solution and match observations from the Southern Ocean. We show that an ~15% wind work increase, applied at high temporal frequency, results in a LFHFW solution with an ~25% increase in the conversion from available to eddy kinetic energy (EKE) and with a corresponding increase in the rate of EKE dissipation. Phenomenologically we observe amplification in the transition from mesoscales to submesoscales and enhancement of submesoscale instabilities. These results suggest that HF wind forcing and NIWs may play an important role in determining the energy pathways in the upper ocean.