Efficient numerical simulation of ocean hydrodynamics by a splitting procedure

A splitting algorithm for fast and slow modes of ocean hydrodynamics is presented. The purpose of the splitting is to reduce the large amount of computational work needed for simulating long real-time periods. The essential point of the splitting is that the external gravity wave terms are extracted from the fully three-dimensional equations of horizontal motion, allowing the reduced equations to be integrated with a larger time step than the original model. The fast external gravity waves are traced by a depth integrated system which is weakly coupled to the reduced three-dimensional momentum equations. The split model shows a radical decrease in computational time and the accuracy is of the same order as in the non-split case.