Energy flux and generation of diurnal shelf waves along Vancouver Island.

Abstract

Recent observations along the west coast of Vancouver Island reveal strong diurnal period currents due to a tidally driven continental shelf wave superimposed upon a kelvin wave. The energy flux of this system is investigated. It is shown that both the Kelvin wave and the first mode continental shelf wave transport energy toward the northwest in the direction of phase propagation, but when the two waves are superimposed the combined energy flux vectors form meanders and gyres over the continental shelf; the pattern repeats in the alongshore direction every wavelength of the shelf wave. Near Southern Vancouver Island these waves combine to form a gyre in which the nearshore side carries energy to the southwest toward Juan de Fuca Strait. Kinetic energy flows up Strait until it is dissipated in narrow tidal channels. (from author's abstract)