Vortical motions (e.g., mesoscale and submesoscale flows) and wavy motions (e.g., internal gravity waves) constitute two fundamental dynamical components of oceanic circulation. Quantifying the transfer of kinetic energy (KE) between and within these distinct flow regimes remains a critical yet unresolved challenge in understanding oceanic energy pathways. Here, we combine a recently developed dynamical decomposition framework with a coarse-graining approach to separate the velocity field into vortical and wavy contributions, and to quantify the cross-scale KE transfers arising from interactions within and between these components. Applying this methodology to the Luzon Strait in the South China Sea, we find a pronounced forward energy cascade that is primarily sustained by wave–wave interactions, with wave scattering playing a secondary role. Notably, direct eddy–wave interactions also induce a forward cascade in the surface layer; below the surface, however, the cascade direction shifts from forward to inverse as the scale increases. These findings reveal the distinct imprints of vortical and wavy motions on oceanic KE cascades and underscore the necessity of accounting for their interplay in future observational and modeling studies.

多尺度相互作用,能量串级,南海,内波,亚中尺度,中尺度涡