Table Of ContentEarth Rotation: Solved and Unsolved Problems
NATO ASI Series
Advanced Science Institutes Series
A series presenting the results of activities sponsored by the NATO Science Committee,
which aims at the dissemination of advanced scientific and technological knowledge,
with a view to strengthening links between scientific communities.
The series is published by an international board of publishers in conjunction with the
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A Life Sciences Plenum Publishing Corporation
B Physics London and New York
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and Physical Sciences Dordrecht, Boston, Lancaster and Tokyo
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F Computer and Systems Sciences Springer-Verlag
G Ecological Sciences Berlin, Heidelberg, New York and Tokyo
Series C: Mathematical and Physical Sciences Vol. 187
Earth Rotation:
Solved and Unsolved Problems
edited by
Anny Cazenave
Groupe de Recherche de Geodesie Spatiale,
Centre National d'Etudes Spatiales,
Toulouse, France
o.
Reidel Publishing Company
Dordrecht / Boston / Lancaster / Tokyo
Published in cooperation with NATO Scientific Affairs Division
Proceedings of the NATO Advanced Research Workshop on
Earth Rotation: Solved and Unsolved Problems
Chateau de Bonas, Gers, France
11-13 June 1985
Library of Congress Cataloging in Publication Data
NATO Advanced Research Workshop on Earth Rotation: Solved and Unsolved Problems
(1985 : Gers, France) Earth rotation - solved and unsolved problems.
(NATO ASI series. Series C, Mathematical and physical sciences; vol. 187)
"Published in cooperation with NATO SCientific Affairs Division."
"Proceedings of the NATO Advanced Research Workshop on Earth Rotation: Solved
and Unsolved Problems, ChAteau de Bonas, Gers, France, 11-13 June 1985"-T.p. verso.
Includes bibliographies.
1. Earth-Rotation-Congresses. I. Cazenave, Anny. II. Title. III. Series:
NATO ASI series. Series C, Mathematical and physical sciences; no. 187.
QB633.N38 1985 525/.35 86-17826
ISBN-13: 978-90-277-2333-8 e-ISBN-13: 978-94-009-4750-4
001: 10. 1007/978-94-009-4750-4
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TABLE OF CONTENTS
Preface vii
List of Participants ix
List of Authors xiii
References Systems and Observation of the Earth's
Rotation Parameters
C. BOUCHER / Celestial Reference Systems
N. CAPITAINE / The Conceptual and Conventional Definitions of
the Earth Rotation Parameters 9
P. PAQUET / How to Measure the Earth Rotation 25
M. SOURIAU and C. ~OSEMBERG-BOROT / Polar Motion and Signal
Processing 45
w. E. CARTER and D. S. ROBERTSON / Accurate Earth Orientation
Time Series from VLBI Observations 61
Historical and Paleoobservations of the Earth's
Rotation - Secular Variations
L. V. HORRISON and F. R. STEPHENSON / Observations of .secular
and Decade Changes in the Earth's Rotation 69
P. MELCHIOR / Earth Rotation and Solid Tides 79
F. MIGNARD / Tidal and Non Tidal Acceleration of the Earth's
Rotation 93
A. BERGER and CHR. TRICOT / Global Climatic Changes and
Astronomical Theory of Paleoclimates 111
Short Term Atmospheric and Oceanic Effects
R. D. ROSEN / Meteorological Data for Earth Rotation Studies 131
J. O. DICKEY, T. l'1. EUBANKS and J. A. STEPPE / High Accuracy
Earth Rotation and Atmospheric Angular Momentum 137
T. H. EUBN~KS, J. A. STEPPE and J. O. DICKEY / The fa-Nino,
the Southern Oscillation and the Earth Rotation 163
D. DJUROVIC / The Atmospheric Circulation, the Earth's Rotation
and Solar l\ctivity 187
vi TABLE OF CONTENTS
J. A. GONELLA I Ocean-Atmosphere Coupling and Short Term
Fluctuations of Earth Rotation 193
S. R. DICKMAN I The Damping of the Chandler Wobble and the
Pole Tide 203
Mantle and Core Effects
A. SOURIAU I The Influence of Earthquakes on the Polar Motion 229
C. GIRE and J. L. LE MODEL I Flow in the Fluid Core and Earth's
Rotation 241
M. PAULUS and M. STIX I Electromagnetic Core-Mantle Coupling 259
v. DEHANT I Global Earth ~odels and Earth Rotation 269
J. HINDERER I Resonance Effects of the Earth's Fluid Core 277
D. E. SMYLIE and M. G. ROCHESTER I Long Period Core Dynamics 297
Recommendations 325
Subject Index 327
PREFACE
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').
The others papers of this session were devoted to the various methods
of observation of the Earth's rotation parameters. For short terms
irregularities (years or less) new techniques based on tracking of
artificial satellites, Lunar-Laser Ranging and Long Base Interferometry
have now supplanted astrometric methods, but as underlined by several
speakers, systematic errors affecting each method are not yet fully
estimated.
For decade and secular variations, the best approach remains
based on observations of solar eclipses (second session). Recompu
tation of secular changes in the length of day shows a clear evidence
for a non tidal component of acceleration in the last millenia, which
could be explained by a change in J 2 resulting from post glacial
uplift. A review of the sp.fctr~m of climatic variations and possible
causes in the range 10 -10 years was presented. During the
Quaternary ice age, changes in the mean global temperature and
subsequent changes in the ice budget and mean sea level could have
induced large changes in the Earth rotation.
Changes in the angular momentum of the atmosphere drive most of
the fluctuations in the length of day over times of a year or less
vii
viii PREFACE
(third session). The residuals are now known well enough to inves
tigate the role of the oceans in the Earth angular momentum budget.
However, while estimates of atmospheric momentum are directly avai
lable from the atmospheric models used in weather forecasting, similar
oceanic estimates are currently not available. These estimates could
be used to explore the interchanges of angular momentum between
oceans, atmosphere and Solid Earth. The two main problems of the
Chandler wobble (excitation and dissipation) have been discussed in
the fourth session. The two most likely candidates for dissipating
wobble energy are mantle anelasticity and dynamic response of the
oceans to wobble. Concerning the Chandler wobble excitation there is
strong evidence that the direct effect of recent earthquakes cannot
supply sufficient power. Examination of boundary layer flows at the
core-mantle boundary, on the other hand, leads to the conclusion that
these may exert sufficient pressure coupling on an elastic mantle to
excite a significant part of the Chandler wobble. Models of electro
magnetic coupling have been shown to be able to produce fluctuations
in the length of day which are quite well correlated with observations
over the last century. Presentations of core dynamics models have
ended this last session. To conclude the workshop, general recomman
dations have been formulated. These appear at the end of this book.
Lectures have been given by scientists of international fame who
made important contributions in the recent years. Much discussion took
place informally during and after the lectures, leading to many
fruitfull interactions between lecturers and participants. It was an
unanimous impression that the workshop was a success.
We are very grateful to NATO who allowed this workshop to take
place offering financial support and travel grants to most parti
cipants. We thank also the council of Europe for its co-sponsorship
which has been much helpful.
LIST OF ALL PARTICIPANTS
(including the Director (D), Lecturers (L), Students (S)
and other Participants/Observers (0»
MELCHIOR P. Prof. L Observatoire Royal de Belgique
3, Av. Circulaire,
1180-BRUXELLES, BELGIQUE
PAQUET P. Prof. D Observatoire Royal de Belgique
3, Av. Circulaire
1180-BRUXELLES, BELGIQUE
BERGER A. Prof. L Institut d'Astronomie et de
Geophysique G. Lemaitre
Universite de Louvain
2, Chemin du Cyclotron, BP 1348
LOUVAIN LA NEUVE, BELGIQUE
DEHANT V. L Institut d'Astronomie et de
Geophysique, G. Lemaitre
Universite de Louvain
2, Chemin du Cyclotron, BP 1348
LOUVAIN LA NEUVE, BELGIQUE
MORRISON L.V. Prof. L Royal Greenwich Observatory,
Herstmonceux castle Hailsham
East Sussex, BN271RP, UK
ZSCHAU J. Prof. L Institut fUr Geophysik,
Kiel University,
Olshausen Strasse 40-60,
D2300 KIEL, RFA
PAULUS M. Dr. L Institut fUr Sonnen Physik,
Schoneckstrasse 6,
D-7800 FREIBURG, RFA
HAUSCH W. o Institut fUr Physikalische
Geodasie,
6100 DARMSTADT, RFA
LENHARDT H. o Institut fUr Physikalische
Geodasie,
6100 DARMSTADT, RFA
ix
x LIST OF PARTICIPANTS
DJUROVIC G. Dr. o Observatoire de Belgrade,
volgina 7, 11050 Belgrade,
Yougoslavie
DICKMAN S.R. Prof. L Dept of Geological Sciences,
State University of New York
Binghampton, N.Y. 13901, USA
EUBANKS T.M. Dr. L Earth Orientation Measurements
Group, J. P. L. ,
4800 Oak Grove Drive
PASADENA, CA 91109, USA
MUELLER I. Prof. L Dept of Geodetic Science,
Ohio State University
1958 Neil Av., COLOMBUS
OHIO 43210-1247, USA
ROSEN R.D. Dr. L Atmospheric & Environmental
Research INC, 840,
Memorial Drive,
CAMBRIDGE, MAS. 02139, USA
CARTER W.E. Dr. L Geodetic Research & Development
Lab., NOAA-NGS
Rockville, MY 20852, USA
DICKEY J.O. Dr. L Earth Orientation Measurements
Group, J .P.L.,
4800 Oak Grove Drive,
PASADENA, CA 91109, USA
BABCOCK A. Dr. o USNO, Time Service Dept,
Washington DC 20390, USA
SMYLIE D.E. Prof. L Dept of Earth & Atmospheric
Science, York University,
4700 Keele Street,
DOWNSVIEW, ONTARIO, CANADA
FLODMARK S. Dr. L Stockholm University,
11346 Stockholm, SUEDE
BOUCHER C. Dr. L Institut Geographique National,
2, Avenue Pasteur
94160 ST MANDE, FRANCE
CAPITAINE N. Dr. L Bureau International de l'Heure
61, Av. de l'Observatoire,
75014 PARIS CEDEX, FRANCE
