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M2 Internal Tides and Their Observed Wavenumber Spectra from Satellite Altimetry*A near-global chart of surface elevations associated with the stationary M2 internal tide is empirically constructed from multi-mission 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.
Document ID
Document Type
Reprint (Version printed in journal)
External Source(s)
Ray, R. D. (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Zaron, E. D. (Scientific Collaborator)
Date Acquired
March 17, 2017
Publication Date
December 21, 2015
Publication Information
Publication: Journal of Physical Oceanography
Volume: 46
ISSN: 0022-3670
Subject Category
Geosciences (General)
Report/Patent Number
Distribution Limits