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EGS-AGU-EUG XXVII General Assembly (Nice, France)
Abstract. Large-amplitude, tidally-driven, internal waves have been observed repeatedly in a tidal channel of the St. Lawence Estuary (Canada). The generation sites of the waves are uncertain but observations from land-based, time-lapse photographies reveal their propagation and destination: before dissipating en route they collide with the shoaling lateral boundaries of the channel. In this presentation we examine whether those periodic wave-boundary collisions play a role in mixing estuarine water properties. Results from nonhydrostatic model simulations show that these waves break, rather than reflect, when they collide with the boundaries which enhances vertical mixing locally. Indirect inference of turbulent buoyancy fluxes also suggest that boundary mixing induced by internal wave breaking represent a significant fraction of the basin-averaged vertical diffusion and may be important for the overall dynamics of such estuaries.
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