An experimental investigation of energy transmission from an evanescent to a propagating region.

Tidal flow over oceanic~bathymetry~is a well known generator of internal waves. However, in the deep ocean there are many~regions of weak stratification and the tides will~generate only evanescent waves~which decay exponentially as they propagate away from their source. In locations where stronger stratification exists above the weak, evanescent waves can form~propagating internal waves as they approach a depth with a stratification corresponding to their frequency (turning depth). An experimental study of the energy transfer from evanescent regions to propagating regions due to evanescent waves passing through a turning depth~is presented.~The effects of varying exponential stratification profiles and single and multi-peak topographical features are described and results are compared with linear theory approximations.~