JPL Geophysicist Solves Mystery of Earth’s ‘Chandler Wobble’

Geophysicist Richard S. Gross of the Jet Propulsion Laboratory has solved the mystery of the Earth’s “Chandler wobble,” a minute oscillation that has tantalized researchers for more than a century. Discovered in 1891 by Seth Carlo Chandler Jr., the wobble is a displacement of about 20 feet at the North Pole with a period of 433 days.

Using oceanic data that has only recently become available, Gross reports in the Aug. 1 Geophysical Research Letters that the principal cause of the Chandler wobble is fluctuating pressure on the bottom of the ocean, caused by temperature and salinity changes, and wind-driven changes in the circulation of the oceans.

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--Compiled by Times medical writer Thomas H. Maugh II