Dennis D. McCarthy

Published by the American Geophysical Union as part of the Geophysical Monograph Series, Volume 59. As part of the Nineteenth General Assembly of The International Union of Geodesy and Geophysics Symposium (IUGG) in Vancouver, Canada, Union Symposium U4, "Variations in Earth Rotation" was held August 18-19 1987. The Convenor was Dennis D. McCarthy, U.S. Naval Observatory with P. Paquet, Observatoire Royal de Belgique and M. G. Rochester, St. Johns University serving as co-convernors. In a session on internal structure of the Earth papers dealt with the geophysical effects on Earth rotation parameters. Mantle anelasticity increases the free core nutation (FCN) period by a few days. The period of the FCN and the amplitudes of the main nutation components are sensitive to the ellipticity of the core?]mantle boundary (CMB), and a non-hydrostatic increase of 400m in the flattening of the CMB is a possible explanation of the discrepancies from theory. An alternative suggestion rests on the subseismic description of the nutation spectrum of the stratified liquid core. Evidently new models will have to take into account contributions from the oceans, mantle anelasticity, non-hydrostatic pre-stress, CMB topography and internal core structure.

Variations in Earth Rotation

Steven J. Dick

Brian Luzum

Annotation Contains 64 papers September 1999 colloquium The historical sessions review the history of early polar motion research and the International Latitude Service. The scientific sessions discuss observational techniques for polar motion, long-term polar motion, Chandler and annual polar motion, daily and subdaily polar motion, and modern definition of the Celestial Ephemeris Pole. Topics include time and polar motion in early NASA spacecraft navigation, secular variation of Carloforte latitude, and comparison of the short period rigid earth nutation series. Annotation c. Book News, Inc., Portland, OR (booknews.com)

Historical and Scientific Problems

Polar Motion

P. Kenneth Seidelmann

This accessible reference presents the evolution of concepts of time and methods of time keeping, for historians, scientists, engineers, and educators. The second edition has been updated throughout to describe twentieth- and twenty-first-century advances, progress in devices, time and cosmology, the redefinition of SI units, and the future of UTC.

Dennis D. McCarthy

About

Books

Join the club