Three-dimensional double-ridge internal tide resonance in Luzon Strait

TitleThree-dimensional double-ridge internal tide resonance in Luzon Strait
Publication TypeJournal Article
Year of Publication2014
AuthorsBuijsman M.C, Klymak J.M, Legg S., Alford MH, Farmer D., MacKinnon JA, Nash J.D, Park J.H, Pickering A., Simmons H.
JournalJournal of Physical Oceanography
Volume44
Pagination850-869
Date Published2014/03
Type of ArticleArticle
ISBN Number0022-3670
Accession NumberWOS:000332425700018
KeywordsAtm; baroclinic tides; circulation; dynamics; energetics; generation; internal waves; model; modeling; Models and; Numerical analysis; ocean; ocean models; Ocean Structure; Phenomena; Physical Meteorology and Climatology; propagation; Regional models; Resonance; scattering; solitary waves; south china sea; tides; topography
Abstract

The three-dimensional (3D) double-ridge internal tide interference in the Luzon Strait in the South China Sea is examined by comparing 3D and two-dimensional (2D) realistic simulations. Both the 3D simulations and observations indicate the presence of 3D first-mode (semi)diurnal standing waves in the 3.6-km-deep trench in the strait. As in an earlier 2D study, barotropic-to-baroclinic energy conversion, flux divergence, and dissipation are greatly enhanced when semidiurnal tides dominate relative to periods dominated by diurnal tides. The resonance in the 3D simulation is several times stronger than in the 2D simulations for the central strait. Idealized experiments indicate that, in addition to ridge height, the resonance is only a function of separation distance and not of the along-ridge length; that is, the enhanced resonance in 3D is not caused by 3D standing waves or basin modes. Instead, the difference in resonance between the 2D and 3D simulations is attributed to the topographic blocking of the barotropic flow by the 3D ridges, affecting wave generation, and a more constructive phasing between the remotely generated internal waves, arriving under oblique angles, and the barotropic tide. Most of the resonance occurs for the first mode. The contribution of the higher modes is reduced because of 3D radiation, multiple generation sites, scattering, and a rapid decay in amplitude away from the ridge.

DOI10.1175/jpo-d-13-024.1
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