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Article
M2 Internal Tides and Their Observed Wavenumber Spectra from Satellite Altimetry
Journal of Physical Oceanography
  • Richard D. Ray, NASA Goddard Space Flight Center
  • Edward D. Zaron, Portland State University
Document Type
Article
Publication Date
1-1-2016
Subjects
  • Wavenumber,
  • Altimetry,
  • Cryosphere,
  • Wavelengths
Abstract
A near-global chart of surface elevations associated with the stationary M2 internal tide is empirically constructed from multimission satellite altimeter data. An advantage of a strictly empirical mapping approach is that results are independent of assumptions about ocean wave dynamics and, in fact, can be used to test such assumptions. A disadvantage is that present-day altimeter coverage is only marginally adequate to support mapping such short-wavelength features. Moreover, predominantly north–south ground-track orientations and contamination from nontidal oceanographic variability can lead to deficiencies in mapped tides. Independent data from Cryosphere Satellite-2 (CryoSat-2) and other altimeters are used to test the solutions and show positive reduction in variance except in regions of large mesoscale variability. The tidal fields are subjected to two-dimensional wavenumber spectral analysis, which allows for the construction of an empirical map of modal wavelengths. Mode-1 wavelengths show good agreement with theoretical wavelengths calculated from the ocean’s mean stratification, with a few localized exceptions (e.g., Tasman Sea). Mode-2 waves are detectable in much of the ocean, with wavelengths in reasonable agreement with theoretical expectations, but their spectral signatures grow too weak to map in some regions.
Description

To the best of our knowledge, this work was authored as part of the Contributor's official duties as an Employee of the United States Government and is therefore a work of the United States Government. In accordance with 17 U.S.C. 105, no copyright protection is available for such works under U.S. Law.

This is the publisher’s final pdf. The article can be found online at: http://dx.doi.org/10.1175/JPO-D-15-0065.1.

DOI
10.1175/JPO-D-15-0065.1
Persistent Identifier
http://archives.pdx.edu/ds/psu/19324
Citation Information
Ray, R. D., & Zaron, E. D. (2016). M2 Internal Tides and Their Observed Wavenumber Spectra from Satellite Altimetry*. Journal Of Physical Oceanography, 46(1), 3-22. doi:10.1175/JPO-D-15-0065.1