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Science 23 January 1981:
Vol. 211. no. 4480, pp. 386 - 389
DOI: 10.1126/science.211.4480.386
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Articles

Solar Cycle Signal in Earth Rotation: Nonstationary Behavior

ROBERT G. CURRIE 1

1 Laboratory for Atmospheric Sciences, NASA Goddard Space Flight Center, Greenbelt, Maryland 20771

Following the discovery of the 11-year solar cycle signal in earth rotation, linear techniques were employed to investigate the amplitude and phase of the difference between ephemeris time and universal time (DgrT) as a function of time. The amplitude is nonstationary. This difference was related to Dgr(LOD), the difference between the length of day and its nominal value. The 11-year term in Dgr(LOD) was 0.8 millisecond at the close of the 18th century and decreased below noise level from 1840 to 1860. From 1875 to 1925, Dgr(LOD) was about 0.16 millisecond, and it decreased to about 0.08 millisecond by the 1950's. Except for anomalous behavior from 1797 to 1838, DgrT lags sunspot numbers by 3.0 ± 0.4 years. Since DgrT lags Dgr(LOD) by 2.7 years, the result is that Dgr(LOD) is approximately in phase with sunspot numbers.

Submitted on May 23, 1980
Revised on July 24, 1980

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Science. ISSN 0036-8075 (print), 1095-9203 (online)