Internal Tide Generation Using Green Function Analysis: To WKB or Not to WKB?
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Internal Tide generation.pdf
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1.81 MB
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Author(s)
Mathur, Manikandan
Carter, Glenn S.
Peacock, Thomas
Date Issued
June 2016
Journal
Journal of Physical Oceanography
Publisher
American Meteorological Society
Citation
Mathur, Manikandan, Glenn S. Carter, and Thomas Peacock. “Internal Tide Generation Using Green Function Analysis: To WKB or Not to WKB?” Journal of Physical Oceanography 46.7 (2016): 2157–2168. © 2016 American Meteorological Society
Version
Final published version
Abstract
An established analytical technique for modeling internal tide generation by barotropic flow over bottom topography in the ocean is the Green function–based approach. To date, however, for realistic ocean studies this method has relied on the WKB approximation. In this paper, the complete Green function method, without the WKB approximation, is developed and tested, and in the process, the accuracy of the WKB approximation for realistic ridge geometries and ocean stratifications is considered. For isolated Gaussian topography, the complete Green function approach is shown to be accurate via close agreement with the results of numerical simulations for a wide range of height ratios and criticality; in contrast, the WKB approach is found to be inaccurate for small height ratios in the subcritical regime and all tall topography that impinges on the pycnocline. Two ocean systems are studied, the Kaena and Wyville Thomson Ridges, for which there is again excellent agreement between the complete Green function approach and numerical simulations, and the WKB approximate solutions have substantial errors. This study concludes that the complete Green function approach, which is typically only modestly more computationally expensive than the WKB approach, should be the go-to analytical method to model internal tide generation for realistic ocean ridge scenarios.
MIT Department
Massachusetts Institute of Technology. Department of Mechanical Engineering
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DOI of Published Version
https://doi.org/10.1175/jpo-d-15-0145.1
