Recent Earth oblateness variations: unraveling climate and postglacial rebound effects.
Earth's dynamic oblateness (J2) has been decreasing due to postglacial rebound (PGR). However, J2 began to increase in 1997, indicating a pronounced global-scale mass redistribution within Earth's system. We have determined that the observed increases in J2 are caused primarily by a recent surge in subpolar glacial melting and by mass shifts in the Southern, Pacific, and Indian oceans. When these effects are removed, the residual trend in J2 (-2.9 x 10(-11) year-1) becomes consistent with previous estimates of PGR from satellite and eclipse data. The climatic significance of these rapid shifts in glacial and oceanic mass, however, remains to be investigated.
Dickey
Jean O
JO
Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109, USA. jean.o.dickey@jpl.nasa.gov
Marcus
Steven L
SL
de Viron
Olivier
O
Fukumori
Ichiro
I