The Wobble and Precession-Nutation on CIP of Elastic Earth

Based on classical dynamical equation on elastic oarth rotation, an associated dynamical equation containing both nutation and wooble of earth rotation has been deduced through introducing motion of nutation frame with respect to inertial spatial frame. Therefore, the theoretical definition of CIP and its dynamical equation on wobble and precession-nutation are given. Considering precession-nutation moment up to 5~(th) order, the authors present the expression of precession-nutation of CIP. Theoretical result shows that odd order's precession-nutation moment causes out-of-phase longitude and obliquity nutation (namely, there are cos term in longitude nutation, and sin term in obliquity nutation). Moreover, it proves that the expression of precession is independent of Earth model. The deduced formulae can serve as a reference and gist in dynamical geodesy and astrogeodynamics' research.