Reflection of linear internal tides from realistic topography: The Tasman continental slope

Jody M. Klymak, Harper L. Simmons, Dmitry Braznikov, Samuel Kelly, Jennifer A. MacKinnon, Matthew H. Alford, Robert Pinkel, Jonathan D. Nash

Research output: Contribution to journalArticlepeer-review

32 Scopus citations

Abstract

The reflection of a low-mode internal tide on the Tasman continental slope is investigated using simulations of realistic and simplified topographies. The slope is supercritical to the internal tide, which should predict a large fraction of the energy reflected. However, the response to the slope is complicated by a number of factors: the incoming beam is confined laterally, it impacts the slope at an angle, there is a roughly cylindrical rise directly offshore of the slope, and a leaky slope-mode wave is excited. These effects are isolated in simulations that simplify the topography. To separate the incident from the reflected signal, a response without the reflector is subtracted from the total response to arrive at a reflected signal. The real slope reflects approximately 65% of the mode-1 internal tide as mode 1, less than two-dimensional linear calculations predict, because of the three-dimensional concavity of the topography. It is also less than recent glider estimates, likely as a result of along-slope inhomogeneity. The inhomogeneity of the response comes from the Tasman Rise that diffracts the incoming tidal beam into two beams: one focused along beam and one diffracted to the north. Along-slope inhomogeneity is enhanced by a partially trapped, superinertial slope wave that propagates along the continental slope, locally removing energy from the deep-water internal tide and reradiating it into the deep water farther north. This wave is present even in a simplified, straight slope topography; its character can be predicted from linear resonance theory, and it represents up to 30% of the local energy budget.

Original languageEnglish (US)
Pages (from-to)3321-3337
Number of pages17
JournalJournal of Physical Oceanography
Volume46
Issue number11
DOIs
StatePublished - 2016

Keywords

  • Continental shelf/slope
  • Internal waves
  • Mixing
  • Regional models

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