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Fortnightly Ocean Tides, Earth Rotation, and Mantle AnelasticityThe fortnightly Mf ocean tide is the largest of the long-period tides (periods between 1 week and 18.6 years), but Mf is still very small, generally 2 cm or less. All long-period tides are thought to be near equilibrium with the astronomical tidal potential, with an almost pure zonal structure. However, several lines of evidence point to Mf having a significant dynamic response to forcing. We use a combination of numerical modeling, satellite altimetry, and observations of polar motion to determine the Mf ocean tide and to place constraints on certain global properties, such as angular momentum. Polar motion provides the only constraints on Mf tidal currents. With a model of the Mf ocean tide in hand, we use it to remove the effects of the ocean from estimates of fortnightly variations in length-of-day. The latter is dominated by the earth's body tide, but a small residual allows us to place new constraints on the anelasticity of the earth's mantle. The result gives the first experimental confirmation of theoretical predictions made by Wahr and Bergen in 1986.
Document ID
20120009846
Acquisition Source
Goddard Space Flight Center
Document Type
Conference Paper
Authors
Ray, Richard (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Egbert, Gary (Oregon State Univ. Corvallis, OR, United States)
Date Acquired
August 25, 2013
Publication Date
September 24, 2012
Subject Category
Oceanography
Report/Patent Number
GSFC.ABS.00366.2012
Distribution Limits
Public
Copyright
Public Use Permitted.

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