ABSTRACT: Stratified tidal flow over a bump.

CGRG Bibliography of Canadian Geomorphology
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Abstract

The dynamics of a stratified flow over and around a topographic feature has broad interest, both in the oceanographic and atmospheric communities. Effects of interest include enhanced form drag, local wake effects, the generation of internal waves, localized mixing, and enhanced upwelling. Many studies have been conducted near 2-dimensional features, such as sills and shelf breaks, but only a few have reported on the effects of stratified flow around 3-dimensional obstacles. The inherent difference is that the flow may bifurcate depending on the strength of the stratification (potential energy) and the speed of the flow (kinetic energy), and either go around the obstacle, or over it. Inevitably, both occur for a range of Froude numbers. The present study will present a series of measurements from moored and ship-mounted ADCPs made near an isolated bump in Juan de Fuca Strait, south of Victoria, BC. The flow is dominated by strong tidal oscillations, with an estuarine circulation providing a continuous source of buoyancy flux to maintain the stratification. Although the tides vary over periods of hours, the flows are quasi-steady in terms of the influence of the bump on the flow structure, and the varying tidal speeds and directions provide a wide range of flow conditions with which to explore Froude number space. It will be shown that a few theoretical flow regimes can be identified in the observations; however, the complexity of the wakes increases for lower Froude number flows, as internal waves communicate perturbations within the flow.

Bibliography of Canadian Geomorphology