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Time-Variable Gravity from Satellite-Laser-Ranging and Doppler Measurements: An Update on the Low-degree components as well as the connections with Geophysical/Climatic ProcessesThe oblateness of the Earth's gravity field, 52, has long been observed to undergo a slight decrease due to post-glacial rebound of the mantle. Sometime around 1998 this trend reversed quite suddenly. This reversal persisted until 2001, at which point the atmosphere-corrected time series appears to have reversed yet again. Presently, the time series appears to be returning to the value that would nominally have been reached had the anomaly not occurred. This anomaly signifies a large interannual change in global mass distribution whose J2 effect overshadows that of the post-glacial rebound over such timescales. A number of possible causes have been considered, with oceanic mass redistribution as the leading candidate although other effects, such as glacial melting and core effects may be contributing. The amount by which J2 returns to it's nominal value provides a valuable constraint on the separation of the causes, and will be considered. We will present our latest Satellite Laser Ranging and DORIS Doppler derived time series for J2, and various other low-degree harmonic terms, as well as our investigations into the causes. In addition, we will show the comparison of the J2 results with those derived from CHAMP, as computed at NASA GSFC, and the recently released GRACE gravity model.
Document ID
20040040131
Acquisition Source
Goddard Space Flight Center
Document Type
Conference Paper
Authors
Cox, Christopher M.
(Raytheon Information Technology and Scientific Services Greenbelt, MD, United States)
Chao, Benjamin F.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Au, Andrew Y.
(Raytheon Information Technology and Scientific Services Greenbelt, MD, United States)
Boy, J.-P.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Date Acquired
August 21, 2013
Publication Date
January 1, 2003
Subject Category
Meteorology And Climatology
Meeting Information
Meeting: American Geophysical Union Meeting
Location: San Francisco, CA
Country: United States
Start Date: December 8, 2003
End Date: December 12, 2003
Sponsors: American Geophysical Union
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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