Earth Rotation Solved And Unsolved Problems

The idea for organl.zl.ng an Advanced Research Workshop entirely devoted to the Earth rotation was born in 1983 when Professor Raymond Hide suggested this topic to the special NATO panel of global transport mechanism in the Geosciences. Such a specialized meeting did not take place since the GEOP research conference on the rotation of the Earth and polar motion which was held at the Ohio State University (USA) in 1973. In the last ten years, highly precise measurements of the Earth's rotation parameters and new global geophysical data have become available allowing major advance to be made in the under standing of the various irregularities affecting the Earth's rotation. The aim of the workshop was to bring together scientists who have made important contributions in this field during the last decade both at the observational and geophysical interpretation levels. The confe rence was divided into four main topics. The first session was dedicated to the definition, implementation and maintenance of the terrestrial and celestial reference systems. A few critical points have been identified as requiring further improvements: (i) appro priate selection of terrestrial sites recognized for their long term stability, (ii) determination of the relationship between terrestrial and celestial references systems as well as between the various terrestrial ones, (iii) improvment of the theory of a rotating elastic earth (the recently adopted theory needs already some corrections').

Astronomy and Astrophysics Abstracts aims to present a comprehensive documen tation of the literature concerning all aspects of astronomy, astrophysics, and their border fields. It is devoted to the recording, summarizing, and indexing of the relevant publications throughout the world. Astronomy and Astrophysics Abstracts is prepared by a special department of the Astronomisches Rechen-Institut under the auspices of the International Astronomical Union. Volume 43 records literature published in 1987 and received before August 15, 1987. Some older documents which we received late and which are not surveyed in earlier volumes are included too. We acknowledge with thanks contributions of our colleagues all over the world. We also express our gratitude to all organiza tions, observatories, and publishers which provide us with complimentary copies of their publications. Starting with Volume 33, all the recording, correction, and data processing work was done by means of computers. The recording was done by our technical staff members Ms. Helga Ballmann, Ms. Beate Gobel, Ms. Monika Kohl, Ms. Sylvia Matyssek, Ms. Doris Schmitz-Braunstein, Ms. Utta-Barbara Stegemann. Mr. Jochen Heidt and Mr. Kristopher Polzine supported our task by careful proof reading. It is a pleasure to thank them all for their encouragement. Heidelberg, October 1987 The Editors Contents Introduction . . . . . . . . . . . 1 Concordance Relation: PHYS-AAA 3 Abbreviations 5 Periodicals, Proceedings, Books, Activities 001 Periodicals . . . . . . . . . . . 10 002 Bibliographical Publications, Documentation, Catalogues, Data Bases 50 003 Books ...... .

The rotation of the Earth and its relation to geomagnetism are topics that have been under debate for more than a century. In this volume both of these phenomena are discussed in the light of new approaches. Keith Runcorn presents a survey of the papers and concluding remarks. F Richard Stephenson gives a thorough review of the history of the Earth's rotation whilst Stig Flodmark finds an explanation for the Chandler wobbles and the drift of the polar axis. A New Approach to Polar Motion by Losito et al. gives another view of the same theory. The fascinating idea of a single-crystal inner core is discussed by Flodmark and Weber and magnetic rigidity in the Earth is a new concept dealt with by Mörner. The mechanisms behind magnetic reversals, ice ages and earthquakes are other subjects under debate. It is hoped that the present volume will encourage forthcoming debates on these subjects.

Over the past ten years, since the MERIT project began in 1980, great changes have taken place and significant advances made in the area of Earth Rotation and Coordinate Reference Frames. Symposium 105, held at the 125th Anniversary Meeting of the International Association of Geodesy, August 1989, was devoted to this subject. Major improvements in techniques, such as VLBI and laser ranging, have been accompanied by corresponding improvements in data-processing procedures and theories of relevant phenomena. The papers included in this volume provide both a comprehensive record of past discoveries and a sound basis for further advances. Section headings are as follows: - Earth Rotation: Determination and Prediction - Earth Rotation: Interpretation - Reference Frames

Earth's Rotation from Eons to Days reviews long-term changes, methods of measurement, and the major influences on rotation parameters. In order to understand secular changes, the momentary behavior of ocean tides must be analyzed and appropriately modelled. Researchers and students in astronomy and all fields of geosciences will find a wealth of information related to the interaction of geophysical phenomena and the rotation of the planet Earth.

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.

Proceedings of the 128th Symposium of the International Astronomical Union, held in Coolfont, West Virginia, USA, October 20-24, 1986.