Turbulent wave energy cascades in an internal wave continuum

Jim Thomas
1Tata Institute of Fundamental Research, Bangalore

Wind and tidally forced regions in the ocean are often seen to have a broad spectrum of waves, forming an internal wave continuum. We explore features of nonlinear wave energy transfers in an internal wave continuum using flow regimes generated with the non-hydrostatic Boussenisq equations. We find that the downscale energy transfers are scale-local, with transfers getting more localized with increasing Rossby number. Additionally, even at low Rossby numbers we find significant broadening of energy across dispersion relationship curves. As a result, less than 50% of the flow energy is associated with pure linear waves. Along with this, we find that the overlap between resonant modes, based on waves’ dispersion relationship, and energy transferring modes are low, implying that a dominant share of the downscale energy transferring modes are non-resonant ones. We also find that physical space regions with low values of divergence and flux magnitudes contain a major share of the integrated energy flux. These results shed light on the intricacies of the energy transfers in the internal wave continuum which can contribute towards development of better wave parameterizations in large-scale ocean models that do not explicitly resolve internal wave dynamics.