On Some Problems of BIH and IPMS Services

1975 ◽  
Vol 26 ◽  
pp. 409-413
Author(s):  
P. Melchior
Keyword(s):  
Polar Motion ◽  
Earth’S Rotation ◽  
Earth's Rotation ◽  
Secular Variations ◽  
General Opinion

The ideas I shall try to develop are probably not original but I hope they reflect a general opinion of those who have looked into the problem of the Earth’s rotation.We must examine here related points:1. The polar motion and the variation of UT1.2. The system of reference with respect to which these periodic or secular variations are described.

Zonal and tesseral harmonic perturbations of an artificial satellite

1966 ◽  
Vol 25 ◽  
pp. 323-325 ◽  
Author(s):  
B. Garfinkel
Keyword(s):  
Angular Velocity ◽  
Spherical Harmonics ◽  
Artificial Satellite ◽  
Compact Form ◽  
Earth’S Rotation ◽  
Earth's Rotation ◽  
Secular Variations ◽  
Tesseral Harmonics

The paper extends the known solution of the Main Problem to include the effects of the higher spherical harmonics of the geopotential. The von Zeipel method is used to calculate the secular variations of orderJmand the long-periodic variations of ordersJm/J2andnJm,λ/ω. HereJmandJm,λare the coefficients of the zonal and the tesseral harmonics respectively, withJm,0=Jm, andωis the angular velocity of the Earth's rotation. With the aid of the theory of spherical harmonics the results are expressed in a most compact form.

Magnitudes and Spectra of Important Dynamical Phenomena

1975 ◽  
Vol 26 ◽  
pp. 63-77
Author(s):  
E. P. Fedotov
Keyword(s):  
Polar Motion ◽  
Continental Drift ◽  
Earth’S Rotation ◽  
Reference Systems ◽  
Coordinate Systems ◽  
Gravitation Field ◽  
Earth's Rotation ◽  
The Earth ◽  
Rigid Attachment ◽  
Body Tides

AbstractThe axes of coordinate systems used in geodynamics are believed to be attached to a number of physical points on the surface of the Earth. This is true when measurements of the distances (ranging) are dealt with. On the other hand, the axes of reference systems used by the BIH and IFMS are attached not to the points themselves but to a pencil of plumb lines at these points. For the case of observations with radio interferometers being used for the study of Earth’s rotation, the rotating frame of reference could be attached in some prescribed way toihebaselines of the interferometers.But in no case is rigid attachment possible, because both the above points and lines move relative to each other. We should search for another way to define the reference systems for geodynamics. With that end in view, a knowledge of magnitudes of pertinent dynamical phenomena becomes vital.This paper considers the effects of some dynamical phenomena upon the distances between the points on. the Earth’s surface and upon the angles between plumb lines and, possibly, also between baselines of radio interferometers. In particular, this paper discusses body tides, continental drift, internal motion within crustal blocks, redistribution of mass which can affect the directions of plumb lines, etc. Polar motion and variations in the rate of Earth’s rotation will be also touched upon as far as these phenomena contribute to deformation of the Earth and its gravitation field.The results are summarised in diagrams showing how the variations of the above distances and angles depend upon both time and positions on the Earth. In other words, the power spectrum of the variation will be presented as a function of time and distance expressed either in kilometers or in degrees of arc on the Earth’s surface.

scholarly journals Polar Motion and Earth Rotation Monitoring in Canada

1979 ◽  
Vol 82 ◽  
pp. 73-74
Author(s):  
J. Popelar
Keyword(s):  
Computer Program ◽  
Earth Rotation ◽  
Polar Motion ◽  
Earth’S Rotation ◽  
Earth's Rotation ◽  
Star Catalogue ◽  
Astronomical Constants

PZT observations of the Earth's rotation and polar motion have been carried out from observatories near Ottawa and Calgary since 1952 and 1968 respectively. A comprehensive re-evaluation and analysis of the PZT data is currently under way, using a new self-contained computer program which can easily accommodate changes of astronomical constants as well as modifications of the star catalogue.

scholarly journals On the Effect of Ocean Tides on the Secular Retardation of the Earth's Rotation

1972 ◽  
Vol 48 ◽  
pp. 240-240 ◽  
Author(s):  
N. N. Pariisky ◽  
M. V. Kuznetsov ◽  
L. V. Kuznetsova
Keyword(s):  
World Ocean ◽  
Classical Problem ◽  
Earth’S Rotation ◽  
Earth's Rotation ◽  
Tidal Waves ◽  
Tidal Forces ◽  
The Earth ◽  
Secular Variations ◽  
Bodily Tides ◽  
Frictional Forces

The classical problem of determining the secular retardation of the Earth's rotation due to the effect of tides (oceanic and bodily) has an important geophysical value in determining the possible existence of processes inside the Earth, which lead to secular variations of rotation of the whole Earth or its external layers.Using new cotidal charts of the world ocean calculated by Bogdanov for the main tidal waves M2, S2, K1 and O1 and using the method of moments of tidal forces the retarding moment was found to be 8.3 × 1023 dyn cm. This is twice the amount of previous evaluations. (This method is superior to the method of calculating the dissipation of energy or the moments of frictional forces). This amount corresponds to a retardation of 3.8 μs/century in the speed of the Earth's rotation. But the observations of the Sun give only 1.9 μs/century for the retardation. Thus, there seem to be nontidal and probably internal processes, which accelerate the Earth's rotation by about 2 μs/century. And this is without taking account of additional smaller effects of bodily tides. The search for these processes is an important problem.The full text of the paper will be published in the magazine Physics of the Earth, No. 2, 1972.

scholarly journals Earth’s Rotation and Polar Motion Based on Global Positioning System Satellite Data

1981 ◽  
Vol 63 ◽  
pp. 173-179
Author(s):  
R. J. Anderle ◽  
L. K. Beuglass ◽  
J. T. Carr
Keyword(s):  
Global Positioning System ◽  
Satellite Data ◽  
Polar Motion ◽  
Computational Techniques ◽  
Earth’S Rotation ◽  
Positioning System ◽  
Earth's Rotation ◽  
Global Positioning ◽  
Instrument Accuracy

AbstractUsing current procedures, polar motion and Earth’s rotation can be computed from 7 days of observations from four stations to four Global Positioning System Satellites to an accuracy of 1.5 m and .3 msec/day, respectively. Improved computational techniques or instrument accuracy and/or measurements from additional satellites or stations would give significant improvements in accuracy.

scholarly journals On the Coordinate Systems Used in the Study of Polar Motion

1979 ◽  
Vol 82 ◽  
pp. 89-101
Author(s):  
E. P. Fedorov
Keyword(s):  
Reference Frame ◽  
Reference System ◽  
Polar Motion ◽  
Earth’S Rotation ◽  
Coordinate Systems ◽  
Earth's Rotation ◽  
The Earth ◽  
Rotation Of The Earth ◽  
Selection Of

IAU Symposium No. 78 “Nutation and the Rotation of the Earth” held in Kiev in 1977 revealed a certain lack of precision in the fundamental concepts and some looseness of terminology employed in the treatment of this problem. When talking about polar motion we should give, first of all, rigorous conceptual definitions of both the pole and a reference frame in which it moves. The selection of a reference system was the topic of an IAU Colloquium held in Torun in 1974. Although the discussion there was thorough and comprehensive, it did not result in the removal of all ambiguities which have tarnished discussion of the problems in the understanding of the Earth's rotation.

Variations of the Angles Between the Plumb Lines of the Astronomical Instruments

1975 ◽  
Vol 26 ◽  
pp. 79-84 ◽  
Author(s):  
N. T. Mironov
Keyword(s):  
Polar Motion ◽  
Earth’S Rotation ◽  
Proper Motions ◽  
Earth's Rotation ◽  
Crustal Movements ◽  
Astronomical Instruments

Systematic latitude and time observations at points A1, A2,…, Anon the Earth’s surface are capable of giving variations ot the angles between the plumb lines at these points or the arcs Sijconnecting the zeniths of these points. The variations may be both real and spurious. The former are due to crustal movements, variations in the direction of gravity, etc. The latter may result from errors of the adopted proper motions of observed stars and certain instrumental errors. The variation ΔSij. is completely independent of the polar motion and changes in the speed of the Earth’s rotation.

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