Oceanic Internal Gravity Waves: sources, sinks, and interactions with the eddy field. 

Abstract: The global oceanic overturning circulation and the transport of heat and dissolved gases are strongly controlled by upper ocean turbulent mixing that is driven by the breaking of internal gravity waves (IWs). Understanding the life cycle of oceanic IWs, from generation to dissipation, is therefore crucial for improving the representation of ocean mixing in climate models, which do not resolve the IW field.  Oceanic IWs are observed to have a continuous energy distribution across spatial and temporal scales – an internal wave continuum – despite being forced primarily at near-inertial and tidal frequencies at large scales. The formation of the IW continuum and the associated energy transfer to dissipative scales have been traditionally attributed to wave-wave interactions and to Doppler shifting of wave frequencies by currents. Here, we provide evidence from realistic numerical simulations that oceanic eddies rapidly diffuse storm-forced wave energy across spatiotemporal scales, thereby playing a dominant role in the formation of the IW continuum and the corresponding spatiotemporal distribution of energy dissipation. We further demonstrate that winds can play an important role in damping oceanic IWs through current feedback.  This results in a substantial reduction in wind power input at near inertial frequencies and a net energy sink for internal tides. Close abstractClose abstract