Internal tide generation at a shelf break by an oblique barotropic tide: observations and analytical modelling - Archive ouverte HAL
Article Dans Une Revue Journal of Geophysical Research. Oceans Année : 1999

Internal tide generation at a shelf break by an oblique barotropic tide: observations and analytical modelling

Résumé

An analytical model has been developed to describe the generation of a linear interfacial wave over a steep ocean margin by a barotropic tide propagating toward the shelf break with a variable angle of incidence. The stratification is reduced to a two-layer system, and the model uses step-like shelf geometry. In both shallow and deep regions an open boundary is assumed (this implies particularly that there is no reflection at the coast). The model is forced with the amplitude and direction of an incident barotropic Poincare wave propagating toward the shelf break. With this forcing, the model gives the amplitude, direction of propagation, and wave number of both barotropic and baroclinic Poincare waves transmitted onto the shelf and reflected into the deep region in the vicinity of the shelf break. After comparisonwith Baines' [1973] model, our model is compared with internal tide observations made in July 1996 on the Malin Shelf within the U.K. Land Ocean Interaction Study-Shelf Edge Study program. The observationsare from moored thermistor chains and acoustic Doppler current profilers sited at two locations, one near the shelf break and the other 47.5 km onto the shelf. Observations at this latter mooring are not described by the generation model because of nonlinear changes and damping as the internal wave propagates through shallow water. Baroclinic displacements of the thermocline of 8 m amplitude were observed close to the shelf break,and total baroclinic energy was estimated at 2.4 J/m3 during neap tide and3 J/m3 during spring tide. Both amplitude and energy of the shoreward propagating internal tide waves are compared with the model. Using a barotropic forcing taken from bibliographical data, good agreement with observations is found during neap tide (when the density structure is close to being two-layer) for an incident barotropic tide of 1 m amplitude and propagation direction on a bearing of 23°T (T means from True North in a clockwise sense).
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Dates et versions

hal-04669092 , version 1 (07-08-2024)

Identifiants

  • HAL Id : hal-04669092 , version 1

Citer

Katell Guizien, Eric Barthélemy, Mark E. Inall. Internal tide generation at a shelf break by an oblique barotropic tide: observations and analytical modelling. Journal of Geophysical Research. Oceans, 1999, 104 (C7), pp.15,655-15,668. ⟨hal-04669092⟩
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