Sub-inertial modulation of nonlinear Kelvin waves in the coastal zone
- 1V. I. Ilichev Pacific Oceanological Institute, Vladivostok, Russia
- 2Vladivostok State University of Economics and Service, Vladivostok, Russia
Abstract. Observational evidence is presented for interaction between nonlinear internal Kelvin waves at the ωt,i (where the ωt is the semidiurnal frequency and the ωi is the inertial frequency) and random oscillations of the background coastal current at the sub-inertial Ω frequency in the Japan/East Sea. Enhanced coastal currents at the sum ω+ and difference ω-frequencies ω±=ωt,i ± Ω have properties of propagating Kelvin waves, which suggests permanent energy exchange from the sub-inertial band to the mesoscale ω± band. This interaction may be responsible for a greater-than-predicted intensification, steepening and breaking of boundary-trapped Kelvin waves. The problem of interaction between the nonlinear Kelvin wave at the frequency ω and the low-frequency narrowband noise with representative frequency Ω≪ω is investigated using the theory of nonlinear weak dispersion waves.