INVESTIGATION OF INTERNAL TIDES EXCITED BY MULTIPLE RIDGES

Laboratory experiments are carried out where internal waves are excited by oscillating bottom topography. An absorbing layer is placed at some distance above the topography to prevent wave reflection from the surface. The topography is two-dimensio nal, and consists of a number of straight ridges with vertical walls and rounded tops. They are oriented perpendicularly to the “tidal flow” (i.e. the direction of the oscillations) and placed per iocially. Resonance phenomena occur when the wave beams emanating from one ridge interact with neighbouring ridges after reflecting at the bottom. Other experiments use sinusoidally shaped ridges or a combination of sinusoidal and vertical ridges. The ultimate purpose of the experiments is to investigate the scaling of the energy flux carried upward by the waves in the regime with stro ngly supercritical topographic slope. Complementary numerical simulations using a non-hydrostatic ocean model will be also used for this purpose.