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Excitation of Earth Rotation Variations "Observed" by Time-Variable GravityTime variable gravity measurements have been made over the past two decades using the space geodetic technique of satellite laser ranging, and more recently by the GRACE satellite mission with improved spatial resolutions. The degree-2 harmonic components of the time-variable gravity contain important information about the Earth s length-of-day and polar motion excitation functions, in a way independent to the traditional "direct" Earth rotation measurements made by, for example, the very-long-baseline interferometry and GPS. In particular, the (degree=2, order= 1) components give the mass term of the polar motion excitation; the (2,O) component, under certain mass conservation conditions, gives the mass term of the length-of-day excitation. Combining these with yet another independent source of angular momentum estimation calculated from global geophysical fluid models (for example the atmospheric angular momentum, in both mass and motion terms), in principle can lead to new insights into the dynamics, particularly the role or the lack thereof of the cores, in the excitation processes of the Earth rotation variations.
Document ID
20050180360
Document Type
Conference Paper
Authors
Chao, Ben F. (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Cox, C. M. (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Date Acquired
August 23, 2013
Publication Date
January 1, 2005
Subject Category
Geophysics
Meeting Information
Spring AGU Joint Assembly(New Orleans, LA)
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.