Numerical modelling concepts for tsunami warning systems

Since the four global oceans are not simply connected in the hydrodynamic sense, separate tsunami warning systems are needed for each ocean. Each ocean shows somewhat different tsunami characteristics, and for this reason, numerical models that are required for the tsunami warning system, also have to be different. These differences stem from whether an ocean gives rise to ocean-wide tsunamis or just to local tsunamis, and also the role played by boundary reflections. Using the concept of method of characteristics it is shown that the hyperbolic, parabolic, elliptic and parabolic-elliptic approaches are respectively valid for the Pacific, Atlantic, Indian and Arctic oceans.