Recent Earth Oblateness Variations: Unraveling Climate and Postglacial Rebound Effects

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Science  06 Dec 2002:
Vol. 298, Issue 5600, pp. 1975-1977
DOI: 10.1126/science.1077777

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Earth's dynamic oblateness (J 2) has been decreasing due to postglacial rebound (PGR). However, J 2 began to increase in 1997, indicating a pronounced global-scale mass redistribution within Earth's system. We have determined that the observed increases in J 2 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 J 2 (–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.

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