Several ray-type 1D and 2D KdV equations for two-layer stratified ocean with topographic effect are derived in detail in the present study.A simplified version of these equations,ray type 1D KdV equation,is used to calculate numerically the disintegration of initial interface soliton from the deep sea to the continental shelf.At the same time,a laboratory experiment is carried out in a 2D stratified flow and internal wave tank to examine the numerical results.A comparison of the numerical results with the experimental results shows that they are in good agreement.The numerical results also show that the ray-type KdV equation has high accuracy in describing the evolution of initial interface waves in shelf/slope regions.Form these results,it can be concluded that the fission process is a dominant generating mechanism of interface soliton packets on the continental shelf.
Based on a nonhydrostatic numerical ocean model developed by one of the authors, the interaction of an internal solitary wave with a step-type topography was investigated. Over the step topography, the flow pattern could be classified into three catego- ries: 1) the propagation and spatial structure of the internal solitary wave was little influenced by the bottom topography, 2) the in- ternal solitary wave was significantly distorted by the blocking effect of the topography without the occurrence of wave breaking and 3) the internal solitary wave was broken as it encountered and passed over the bottom topography. A detailed description of the processes leading to wave breaking is given in this paper together with energy budget analysis. The results revealed that the maxi- mum of the energy dissipation rate is no more than 40%, which is consistent with available experimental data.
