共查询到20条相似文献，搜索用时 31 毫秒
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Summary. The pole tide is the response of the ocean to incremental centrifugal forces associated with the Chandler wobble. The tide has a potentially important effect on the period and damping of the wobble, but it is at present not well constrained by observations. Here, we construct both analytical and numerical models for the pole tide. The analytical models consider the tide first in a global ocean and then in an enclosed basin on a beta-plane. The results are found to approach equilibrium linearly with decreasing frequency and inversely with increasing basin depth. The numerical models solve Laplace's tidal equations over the world's oceans using realistic continental boundaries and bottom topography. The results indicate that the effects of the non-equilibrium portion of the deep ocean tide on the Chandler wobble period and damping are negligible. 相似文献
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The Hamiltonian formalism was recently applied by Getino (1995a,b) for the study of the rotation of a non-rigid earth with a heterogeneous and stratified liquid core. That earth model is generalized here by including the effect of the dissipation arising from the mantle-core interaction, using a model similar to that of Sasao, Okubo & Saito (1980), which includes both viscous and electromagnetic coupling. First, a solution for the free nutations is obtained following a classical approach, which in our opinion is more familiar to most of the readers than the Hamiltonian treatment. This solution provides a theoretical basis clear enough to study both the qualitative and quantitative effects of the dissipations considered in the hypotheses. The main qualitative features are, besides the delays, that the free core nutation (FCN) suffers an exponential damping, while the chandler wobble (CW) is not damped at first order, by the dissipation considered. The numerical values obtained for the complex compliances agree with the most recent experimental computations.
Next, the problem is studied under a Hamiltonian formalism, and a solution equivalent to the above is obtained. Besides its interest from a theoretical point of view, this formalism is necessary in order to apply canonical perturbation methods in order to obtain analytical nutation series. 相似文献
Next, the problem is studied under a Hamiltonian formalism, and a solution equivalent to the above is obtained. Besides its interest from a theoretical point of view, this formalism is necessary in order to apply canonical perturbation methods in order to obtain analytical nutation series. 相似文献
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We derive two new types of invariant that must be obeyed by the radial magnetic field at the core-mantle boundary if the hypothesis of frozen flux is valid and the fluid motion is either toroidal or tangentially geostrophic there. These general invariants incorporate specific invariants that are already known and can, in principle, be tested using magnetic data that cover an interval of time. 相似文献
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The crystal structure of iron in the Earth's inner core 总被引：1，自引：0，他引：1
Colin M. Sayers 《Geophysical Journal International》1990,103(1):285-286
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Raymond Hide 《Geophysical Journal International》1998,135(3):1150-1152
Several dynamic agencies control differential rotation between various regions of a rotating gravitating body such as a planet, namely advection of angular momentum (within fluid regions) and torques due not only to (a) viscous forces, (b) dynamic pressure forces and (c) gravitational forces, but also to (d) Lorentz forces (involving the flow of electric currents in electrically conducting regions), (e) magnetostatic forces (when magnetized material is present) and (f) electrostatic forces (due to the presence of electric charges). Torques due to (a), (b), (c) and (d) have already been treated in the literature, some extensively. It is of general theoretical interest to derive from first principles mathematical expressions for torques due to (e) and (f), even though they turn out to be quantitatively insignificant in the case of the Earth. 相似文献
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