HR: 10:35h
AN: G31C-02    [PDF]
TI: Variations in the Earth's Oblateness During the Past 26 years
AU: Cheng, M
EM: cheng@csr.utexas.edu
AF: Center for Space Research, UT at Austin, 3925 W. Braker Ln. #200, Austin, TX 78759-5321
AU: * Tapley, B D
EM: tapley@csr.utexas.edu
AF: Center for Space Research, UT at Austin, 3925 W. Braker Ln. #200, Austin, TX 78759-5321
AB: Analysis of Satellite Laser Ranging (SLR) data from multiple satellites over 26 years from 1976 to 2002 indicate that the Earth?|s dynamic oblateness, as represented by the J2 coefficient, undergoes both seasonal and long-term variations. The dominant signatures in the observed variations in J2 are (1) a secular decrease with a rate of -2.75x1.0e-11/year, which is mostly due to postglacial rebound, (2) seasonal variations, which have a mean amplitude of 2.9x1.0e-10, associated with the Earth?|s annual mass redistribution and (3) significant interannual variations with time scales of 4-6 years. Two large interannual variations in J2 can be related to the strongest El Ni?o-Southern Oscillation (ENSO) during the periods of 1986-1991 and 1996-2002. The ENSO related large fluctuations cannot be explained by current models since the interannual mass redistributions within the atmosphere, ocean and continental hydrology contain significant uncertainties. The observed fluctuations with 4-6 year time scale indicate the impact of the ENSO phenomenon on the large-scale global mass redistributions within Earth?|s system components.
DE: 1200 GEODESY AND GRAVITY
DE: 1214 Geopotential theory and determination
DE: 1555 Time variations--diurnal to secular
DE: 1600 GLOBAL CHANGE (New category)
SC: Geodesy [G]
MN: 2003 Fall Meeting