The energy balance of mesoscale eddies has been a long-lasting puzzle, with known energy injection being much larger than the dissipation. Internal waves are believed to be one key structure whose interaction with mesoscale eddies leads to downscale energy flux to small scales and finally dissipates energy at the ocean interior. Near-inertial waves can absorb energy from the mesoscale eddies through the stimulated loss of balance mechanism and can induce the downscale flux of mesoscale eddies by its catalytic effect. We accomplish the decomposition of the above two mechanisms through a filtering procedure, specifically, the decomposition of energy transfer across scales and energy conversion between different flow structures. We find that both the stimulated loss of balance and the induced downscale flux mechanisms follow a power-function relation with the energy injection ratio between near-inertial waves and mesoscale eddies until saturation. Statistics of these two effects in spatial-temporal space are also studied. Evidence of wave-induced downscale energy flux is found from observation data.

mesoscale eddy; near-inertial wave; energy transfer