caa a22 4500 445863617 CHVBK 20180317145451.0 cr unu---uuuuu 170323e20110601xx s 000 0 eng 10.1007/s10569-011-9347-1 doi (NATIONALLICENCE)springer-10.1007/s10569-011-9347-1 Kubo Yoshio 5-8-3 Higashi-gotanda, Shinagawa-ku, 141-0022, Tokyo, Japan aut Kinematical modeling of the Earth rotation, focusing on the Oppolzer terms in a rigid Earth and the Oppolzer-like terms in an elastic Earth [Elektronische Daten] [Yoshio Kubo] Under perturbations from outer bodies, the Earth experiences changes of its angular momentum axis, figure axis and rotational axis. In the theory of the rigid Earth, in addition to the precession and nutation of the angular momentum axis given by the Poisson terms, both the figure axis and the rotational axis suffer forced deviation from the angular momentum axis. This deviation is expressed by the so-called Oppolzer terms describing separation of the averaged figure axis, called CIP (Celestial Intermediate Pole) or CEP (Celestial Ephemeris Pole), and the mathematically defined rotational axis, from the angular momentum axis. The CIP is the rotational axis in a frame subject to both precession and nutation, while the mathematical rotational axis is that in the inertial (non-rotating) frame. We investigate, kinematically, the origin of the separation between these two axes—both for the rigid Earth and an elastic Earth. In the case of an elastic Earth perturbed by the same outer bodies, there appear further deviations of the figure and rotational axes from the angular momentum axis. These deviations, though similar to the Oppolzer terms in the rigid Earth, are produced by quite a different physical mechanism. Analysing this mechanism, we derive an expression for the Oppolzer-like terms in an elastic Earth. From this expression we demonstrate that, under a certain approximation (in neglect of the motion of the perturbing outer bodies), the sum of the direct and convective perturbations of the spin axis coincides with the direct perturbation of the figure axis. This equality, which is approximate, gets violated when the motion of the outer bodies is taken into account. Springer Science+Business Media B.V., 2011 Earth rotation nationallicence Precession and nutation nationallicence Rigid Earth nationallicence Elastic Earth nationallicence Angular momentum axis nationallicence Figure axis nationallicence Rotational axis nationallicence Oppolzer terms nationallicence Poisson terms nationallicence Convective terms nationallicence Celestial Mechanics and Dynamical Astronomy Springer Netherlands 110/2(2011-06-01), 143-168 0923-2958 110:2<143 2011 110 10569 https://doi.org/10.1007/s10569-011-9347-1 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s10569-011-9347-1 text/html Onlinezugriff via DOI NATIONALLICENCE 100 1- Kubo Yoshio 5-8-3 Higashi-gotanda, Shinagawa-ku, 141-0022, Tokyo, Japan aut NATIONALLICENCE 773 0- Celestial Mechanics and Dynamical Astronomy Springer Netherlands 110/2(2011-06-01), 143-168 0923-2958 110:2<143 2011 110 10569 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer