The Theory of Nutation and the Variation of Latitude

Abstract

The theory of the bodily tide and of the various nutations is developed. Elasticity of the shell and fluidity of the core are taken into account. The model used for the shell is Takeuchi's Model 2, based on one of Bullen's. The core is replaced by a homogeneous incompressible fluid, with an additional particle at the centre chosen to make the mass and moment of inertia of the core correct. Effects of the ocean are neglected, but can be allowed for at a later stage. The period of the free nutation is found to be 392 days (which would be increased by the ocean). The bodily tide numbers for semidiurnal and long-period tides are: h =0.58, k =0.29, l =0.082. They have other values for diurnal tides, the greatest observable differences from the statical values being for the lunar tide O. The correcting factor for the 19-yearly nutation is 0.9964.