Abstract: 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.

Key words: elastic earth model, precession nutation moment, CIP axis

摘要： 基于经典的弹性地球自转动力学理论，通过引入章动参考系相对惯性空间的运动，建立了弹性地球极移和章动的联合动力学方程。由此对 CIP 轴进行了理论定义，并给出了其极移、岁差章动的动力学方程。在顾及到 5 阶引潮力矩的情况下，给出了 CIP 轴的岁差章动的解析表达式。理论研究表明，奇数阶岁差章动力矩使得黄经章动和交角章动出现了异向项（即黄经章动出现了 cos 项，交角章动出现了 sin 项），同时也证明了岁差表达式与地球模型无关。得出的理论可为动力大地测量学和天文地球动力学的研究提供理论参考和依据。

关键词: 弹性地球模型, 岁差章动力矩, CIP轴