VERTICAL VARIATION OF THE PHASE IN GRAVIT Y-WAVES REFRACTION THEORY

Linearized gravity waves propagating over a ''slowly'' varying bottom are treated by an asymptotic approximation method. We look for an eiko nal solution. The expansion used is compared to the Keller (1958)-Mei (1989) one. That induces a discussion about amplitude and phase defini tion. At the first order, approaches are equivalent but ours shows a v ertical variation of the phase at the second order.