NASA Logo

NTRS

NTRS - NASA Technical Reports Server

Back to Results
Time-Variable Gravity Signal Due to Extratropic Pacific Water Mass RedistributionCox and Chao [2002] reported the detection of a large anomaly in the form of a positive "jump" in the time series of Earth's lowest-degree gravity harmonic J2, or the dynamic oblateness, during 1998. This prompted us to examine the mass redistribution in the global oceans. We report here a seesaw of the sea-surface height (SSH) in the extratropic north + south Pacific basins -- the leading (nonseasonal) EOF/PC mode in SSH derived from the 10-year TOPEX/Poseidon altimetry data in the extratropic Pacific region. The mode underwent a step-like jump with time evolution that match remarkably well with the observed J2 anomaly. However, the magnitude is several times too small to explain the observed J2, even if assuming the SSH jump was all mass-induced (as opposed to any steric effect which causes no time-variable gravity signal). If one accepts the notion that this extratropic Pacific seesaw is part of the geophysical process that produced the observed 1998 J2 anomaly, then this finding suggests strong geophysical connection of the interannual-to-decadal variation of J2 with the Pacific Decadal Oscillation (PDO), as the time series of the above EOF/PC mode is actually a formally defined PDO Index series.
Document ID
20030020809
Acquisition Source
Goddard Space Flight Center
Document Type
Conference Paper
Authors
Chao, Benjamin F.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Au, A. Y.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Cox, C. M.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Date Acquired
August 21, 2013
Publication Date
January 1, 2002
Subject Category
Geophysics
Meeting Information
Meeting: American Geophysical Union Meeting
Location: San Francisco, CA
Country: United States
Start Date: December 6, 2002
End Date: December 10, 2002
Sponsors: American Geophysical Union
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

Available Downloads

There are no available downloads for this record.
No Preview Available