Numerical Solution Of Rotational Polar Motion Of Triaxial Two-layer Earth

The nature of Earth rotation is uniquely determined by Earth model,including the layer structures,geophysical parameters such as principal inertia moments of different layers and the compliances.This study focuses on providing numerical solution of the rotational normal modes of a triaxial two-layered anelastic Earth model without external forces.We provide a relatively complete parameter set which could be applied in other studies.We first formulate the rotation equation of the triaxial two-layered anelastic Earth model and then provide numerical solution of that equation.We obtain eight solutions,of which only four solutions may exist in reality.Further,based on the present choice of the conventional reference systems,only two of these four solutions correspond to the present motion status of the prograde Chandler wobble(CW)and the retrograde free core nutation(FCN).Our calculations show that the periods and quality factors of CW and FCN are respectively 430.46 and 430.22 solar days and 84.9 and 23932.Furthermore,this study also make a thorough research on the relationship between the geophysical compliances and Earth normal modes.Our results show that some compliances,to some degree,may have a magnificent effect on the periods or the quality factors of Earth normal modes.