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Libration in the Earth's rotation
Author(s) -
Chao B. F.,
Dong D. N.,
Liu H. S.,
Herring T. A.
Publication year - 1991
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/91gl02491
Subject(s) - libration (molecule) , rotation (mathematics) , physics , earth's rotation , moment of inertia , amplitude , polar motion , geodesy , rotation around a fixed axis , inertia , polar , geophysics , geology , classical mechanics , geometry , astronomy , optics , point (geometry) , mathematics
External luni‐solar torque exerted on the difference ( B‐A ) of the Earth's two equatorial principal moments of inertia gives rise to two types of librational motions in the Earth's rotation: the semidiurnal libration in spin and the prograde diurnal libration in polar motion. Formulas for the librations considering a realistic Earth model and their tidal decompositions are derived and evaluated. The spin libration has a maximum peak‐to‐peak amplitude of 0.09 milliarcseconds, that of the polar libration is 0.06 milliarcseconds. Implications concerning their detectability and role in the tidal variation of Earth rotation are discussed.