Figure 1 Bathymetry of the Indian Ocean and location of the Mascaren Ridge. The 1000m and 4000m depth contours are shown.
At each station a series of CTD and LADCP profiles were made over a period of 15 hours. From these the amplitude and phase of temperature, salinity and current oscilatons with semi-diurnal period were calculated. The energy flux was then estimated by integration of the product of the hydrostatic pressure and the velocity.
Figure 2. Measureed energy fluxes. The magnitude of the flux is proportional to the size of the arrow head. The largest flux measured at the sill around 13°S was almost 40kW/m.
The amplitude of internal tide radiated from the ridge varies greatly along the length of the ridge. The maximum energy flux (almost 40kW/m) is foumd at the saddle between the Saya de Malha and Nazareth banks. However, on the flanks of these banks the energy flux was of hte orfer of 1 kW/m.
Tidal currents derived from the tidal inverse model of Egbert and Erofeeva suggest that there is very little tidal tranport over the banks, but there is a large tranport funnelled through the saddle between them (see Figure 3).
Figure 3. M2 tidal ellipses calculated from the OSU tidal inverse model (TPX0.6) and bathymetry of the sill between the Saya de Malha and Nazareth banks. The size of the ellipse is proprtional to the depth integrated velocity (tranport).