The influence of a geostrophic current on the internal tide generation
<p>We investigate the influence of a barotropic geostrophic current on<br>internal tide (IT) generation over a shelf slope.<br>The current $V_g(x)$ is modeled as an idealized Gaussian function centered at<br>$x_0$ with width $x_r$ and maximum velocity $V_{max}$.<br>The bathymetry is modelled as a linear slope with smoothed corners.<br>We calculate the total barotropic-to-baroclinic energy conversion $C =<br>\int \overbar{C} \,dx = \int \int \rho' g W \,dx\, dz$.&#160;<br>$\overbar{C}(x,t)$ can be either positive or negative. Positive (negative) conversion means energy is<br>converted from barotropic to baroclinic (baroclinic to barotropic)<br>waves.&#160;<br>The main conclusions are: 1) $V_g(x)$ changes the effective<br>frequency $f_{eff}$. This has a direct impact on the slope of the IT<br>characteristics and the slope criticality, which affects the total<br>conversion rate;<br>2) Since $(V_g)_x$ is not a constant value, $f_{eff}$ varies along the<br>slope. This has a significant effect on the IT beam generation<br>location and its propagation path. If the current is strong enough so<br>that $f_{eff}$ is greater than the barotropic tidal frequency $\sigma_T$, a blocking<br>region is formed where the conversion vanishes and IT propagation is blocked;<br>3) Changes of sign in $\bar{C}(x,t)$ correspond to the locations where<br>IT beams reflect from the boundaries. As a result, the total conversion rate $C$ is<br>also strongly affected by the IT beam pattern.<br>In conclusion, the total conversion rate $C$ is affected by a<br>combination of three factors: slope criticality, size and location of the blocking<br>region and the IT beam patterm, all of which can be varied by changing<br>the strength, width and location of the geostrophic current $V_g(x)$.</p>