HR: 1340h
AN: G33A-0031    [Abstracts]
TI: Body Tides of a Realistic Earth
AU: * Metivier, L
EM: lalmetiv@ipgp.jussieu.fr
AF: Institut de Physique du Globe de Paris, 4, place Jussieu, Paris, 75005 France
AU: * Metivier, L
EM: lalmetiv@ipgp.jussieu.fr
AF: Centre National d'Etudes Spatiales, 2, place Maurice Quentin, Paris, 75001 France
AU: Greff-Lefftz, M
EM: greff@ipgp.jussieu.fr
AF: Institut de Physique du Globe de Paris, 4, place Jussieu, Paris, 75005 France
AU: Diament, M
EM: diament@ipgp.jussieu.fr
AF: Institut de Physique du Globe de Paris, 4, place Jussieu, Paris, 75005 France
AB: A precise modelling of the Earth tides is necessary to correct the space gravimetry observations, from satellites such as GRACE and GOCE. It is also useful to correct ground measurements, and even more important for superconducting gravimeters, which have a 10 nGal precision. The Earth response (deformation and gravity) to tides or atmospheric load is generally computed assuming radial symmetry in stratified Earth models, at the hydrostatic equilibrium. Our study aims at providing a new Earth tide model, which accounts for the whole complexity of a more realistic Earth. Our model is based on a dynamically consistent equilibrium state which includes lateral variations in density and rheological parameters (shear and bulk moduli), and interface topographies. We use a finite element method and we solve numerically the gravito-elasticity equations. The deviation from the hydrostatic equilibrium has been taken into account as a first order perturbation. The equations are written in the Fourier domain, in order to allow degree one translational and rotational modes of the Earth. We investigate the impact on Earth tidal response of an equilibrium state different from hydrostatic and of the topography of the interfaces, for a simple model of lateral variation: a spherical anomaly in the mantle, which can represent plumes and superplumes. At the M2 frequency (semi-diurnal), we estimate the order of magnitude of the perturbation as a function of the radius and physical parameters of the anomaly.
DE: 0560 Numerical solutions (4255)
DE: 1213 Earth's interior: dynamics (1507, 7207, 7208, 8115, 8120)
DE: 1217 Time variable gravity (7223, 7230)
DE: 1219 Gravity anomalies and Earth structure (0920, 7205, 7240)
DE: 7208 Mantle (1212, 1213, 8124)
SC: Geodesy [G]
MN: Fall Meeting 2005