Tidally-forced flow in a rotating, stratified, shoaling basin

TitleTidally-forced flow in a rotating, stratified, shoaling basin
Publication TypeJournal Article
Year of Publication2015
AuthorsWinters KB
JournalOcean Modelling
Date Published2015/06
Type of ArticleArticle
ISBN Number1463-5003
Accession NumberWOS:000355148400006
Keywordsbaroclinic instability; Boundary currents; Cyclonic jet; hawaiian ridge; Internal tide; internal tides; large-scale; Luzon Strait; Poleward eastern; radiation; stability; wave generation

Baroclinic flow of a rotating, stratified fluid in a parabolic basin is computed in response to barotropic tidal forcing using the nonlinear, non-hydrostatic, Boussinesq equations of motion. The tidal forcing is derived from an imposed, boundary-enhanced free-surface deflection that advances cyclonically around a central amphidrome. The tidal forcing perturbs a shallow pycnocline, sloshing it up and down over the shoaling bottom. Nonlinearities in the near-shore internal tide produce an azimuthally independent 'set-up' of the isopycnals that in turn drives an approximately geostrophically balanced, cyclonic, near-shore, sub-surface jet. The sub-surface cyclonic jet is an example of a slowly evolving, nearly balanced flow that is excited and maintained solely by forcing in the fast, super-inertial frequency band. Baroclinic instability of the nearly balanced jet and subsequent interactions between eddies produce a weak transfer of energy back into the inertia-gravity band as swirling motions with super-inertial vorticity stir the stratified fluid and spontaneously emit waves. The sub-surface cyclonic jet is similar in many ways to the poleward flows observed along eastern ocean boundaries, particularly the California Undercurrent. It is conjectured that such currents may be driven by the surface tide rather than by winds and/or along-shore pressure gradients. (C) 2015 Elsevier Ltd. All rights reserved.

Short TitleOcean Model.
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