Abstract
Time integrations of shallow water equations were carried out in order to investigate whether (inertio-) gravity waves are produced or not through upscale energy transfer due to nonlinear wave-wave interactions. Differing from the limitless upscale energy transfer occurred in pure two-dimensional turbulence, the results demonstrate that the upscale energy transfer is weak and is suppressed in the lower wavenumber domain. Initially given gravity waves with random amplitudes and phases produce somewhat inhomogeneous and wave-like patterns at the final decaying stage, which can be identified as large-scale (inertio-) gravity waves. This fact suggests that such nonlinear wave-wave interactions can be regarded as one of the candidates to produce large-scale waves. However, it cannot always be concluded definitely whether the process is an effective mechanism for generation of the large-scale gravity waves in the actual atmosphere or the oceans. Other features of shallow water waves appeared through the process of nonlinear interactions are described in detail.
