Formulation of a three-dimensional shelf edge model and its application to internal tide generation

A brief outline of the major steps in the formulation of a non-linear three-dimensional baroclinic model suitable for studying the generation of the internal tide and associated mixing is presented in the first part of this paper. A two prognostic equation turbulence energy model is used to compute the mixing. A comparison of linear inviscid solutions computed with the model and published solutions in the literature, demonstrate that accurate numerical solutions can be obtained provided the grid is sufficiently fine to resolve the significant vertical and horizontal changes associated with the internal tide. An indication of the grid resolution required in the model is presented in this paper. A comparison of internal tidal current magnitudes, displacements and mixing intensities shows that with strong tidal forcing there are significant differences between the linear and non-linear model. Also in the case of strong forcing the numerical form of the advection scheme used in the density equation is particularly important. A detailed discussion of the reasons for differences in the internal tide computed with linear and non-linear models and the importance of the intensity of the barotropic tidal forcing is presented in this paper.