NASA Logo

NTRS

NTRS - NASA Technical Reports Server

Back to Results
Fortnightly Earth Rotation, Ocean Tides, and Mantle AnelasticitySustained accurate measurements of earth rotation are one of the prime goals of Global Geodetic Observing System (GGOS). We here concentrate on the fortnightly (Mf) tidal component of earth-rotation data to obtain new results concerning anelasticity of the mantle at this period. The study comprises three parts: (1) a new determination of the Mf component of polar motion and length-of-day from a multi-decade time series of space-geodetic data; (2) the use of the polar-motion determination as one constraint in the development of a hydrodynamic ocean model of the Mf tide; and (3) the use of these results to place new constraints on mantle anelasticity. Our model of the Mf ocean tide assimilates more than fourteen years of altimeter data from the Topex/Poseidon and Jason-1 satellites. The polar motion data, plus tide-gauge data and independent altimeter data, give useful additional information, with only the polar motion putting constraints on tidal current velocities. The resulting ocean-tide model, plus the dominant elastic body tide, leaves a small residual in observed length-of-day caused by mantle anelasticity. The inferred effective tidal 0 of the anelastic body tide is 90 and is in line with a omega-alpha frequency dependence with alpha in the range 0.2--0.3.
Document ID
20120001984
Document Type
Conference Paper
Authors
Ray, Richard D. (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Egbert, Gary D. (Oregon State Univ. Corvallis, OR, United States)
Date Acquired
August 25, 2013
Publication Date
December 5, 2011
Subject Category
Geophysics
Report/Patent Number
GSFC.ABS.5624.2011
Meeting Information
American Geophysical Union Fall Meeting 2011(San Francisco, CA)
Distribution Limits
Public
Copyright
Other