On the dynamical effects of an inhomogeneous liquid core in the theory of nutation

As shown in previous work, dynamical effects of a realistic model of a heterogeneous, compressible, stably stratified liquid core may be obtained by means of a simple analysis of the generalized two-dimensional Laplace tidal equation which describes tidal flows of an incompressible and non-gravitating fluid in a thin spherical layer with mobile boundaries. The solution was presented in the form of expansions in powers of a small parameter κ being the ratio of nutational motion frequency in space to the frequency of the Earth's diurnal rotation. Whereas in an earlier paper only first-order terms were taken into account, our present approach includes not only main second-order terms in the spherical harmonic expansions of the solutions, but also the terms of higher orders. These effects are calculated numerically for realistic models of the Earth's outer liquid core, solid inner core and anelastic mantle (PREM model). All tables are found in electronic version at http://www.tu-darmstadt.de/fb/vw/ipg/Welcome2.html Received: 12 June 1997 / Accepted: 11 December 1997