Radiation of Energy from Nonzonal Ocean Currents, Nonlinear Regime. Part I: Single Wave Development*

Abstract

The energy radiation from oceanic boundary currents is assumed to be one of the main mechanisms responsible for the production of the highly energetic eddy field in the interior of the ocean. The efficiency of the process is demonstrated in an example of a simple model of a nonzonal flow. The nonzonal orientation of the current proves to be a key dynamical factor setting the radiation in the model. The effects of the nonlinear interactions on the radiating properties of the solution are studied in detail numerically. The efficient numerical algorithm with open boundary conditions is used. The solutions of the linear problem reported previously by Kamenkovich and Pedlosky are used as initial conditions. The results show that even rapidly growing linear solutions, which are trapped during the initial stage of development, can radiate energy in the nonlinear regime if the basic current is nonzonal. The radiation starts as soon as the initially fast exponential growth significantly slows. The initial apparent trapping of those solutions is caused by their fast temporal growth. The new mechanism for radiation is related to the nonzonality of a current.