Open AccessForced nutations of a rigid mantle‐liquid core earth model in canonical formulation
Author(s) -
Getino Juan
Publication year - 1995
Publication title -
geophysical journal international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.302
H-Index - 168
eISSN - 1365-246X
pISSN - 0956-540X
DOI - 10.1111/j.1365-246x.1995.tb06839.x
Subject(s) - nutation , inner core , outer core , mantle (geology) , earth model , physics , earth's rotation , amplitude , classical mechanics , formalism (music) , structure of the earth , geophysics , geology , geodesy , optics , quantum mechanics , art , musical , visual arts
SUMMARY The canonical formalism for the rotation of an earth model composed of a rigid mantle and a liquid core, established in Getino (1995b), starting from the model of Sevilla & Romero (1987), is applied here to the study of the forced nutations caused by the perturbing lunisolar potential. The main purpose of this paper is not to get accurate values for the nutation terms, since the earth model considered does not include the effect of the elasticity. This approach should be understood as a generalization of Kinoshita's (1977) theory for a rigid earth. Under the canonical formulation, using Andoyer‐like variables and following a procedure very similar to that of Kinoshita, we obtain similar expressions (to those of Kinoshita) for the nutations of the fundamental planes, the only difference being a corrector factor f c in the amplitudes of the nutation to account for the effect of the liquid core. This corrector factor is equal to 1 when particularizing for the rigid case; the results are then the same as those of Kinoshita. In this way, we develop a complete canonical theory for a non‐rigid earth (not as yet including deformations) which includes the effect of the liquid core from the beginning. and which enables the amplitudes of the forced nutations to be obtained directly, unlike the usual theories for a non‐rigid earth, which require the support of results for the rigid case.