| Popis: |
We investigate the influence of a barotropic geostrophic current onthe internal wave (IW) generation over a shelf slope.It is well known that most of the energy in the tide-topographygenerated waves lies in waves with tidal frequency $\sigma_T$. Here we restrict our attention on the frequencies other than the dominant frequency $\sigma_T$. The current $V_g(x)$ is modeled as an idealized Gaussian function centered at$x_0$ with width $x_r$ and maximum velocity $V_{max}$.The bathymetry is modelled as a linear slope with smoothed corners.Since the center of the current lies on the slope, there will alwaysbe a region on the slope where the effective frequency $f_{eff}$ isgreater than the Coriolis parameter $f$ and another region where$f_{eff} < f$. Parametric subharmonic instability (PSI) occurs wherewaves with approximately half of the primary wave frequency, in thiscase $\sigma_T/2$, are generated. In the presence of a large current,PSI can occur where $f_{eff} < \sigma_T/2 < f$. This could nothappen without a current, i.e. $f_{eff} = f > \sigma_T/2$. Other interestinginteractions, including interharmonics and strong tidal harmonics, are also observed. |
