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Rotation terrestre et Variations du champ de gravité : Etude et apport des missions CHAMP et GRACE

Abstract : The masses distributions inside the Earth govern the Earth rotation rate, as well as the behaviour of the rotation axis in the Earth and in space. These distributions of masses can be measured by space owing to artificial satellites, the orbitography of which provides the Earth gravity field determination. Then, the temporal variations of the Earth gravity field can be related to the variations of the Earth Orientation Parameters (with the Inertia Tensor). Huge improvements have been made in the last years in the modelisation of the fluid layers effect on the Earth rotation. And nowadays, the Earth orientation measurements in space, obtained with Very Long Baseline Interferometry (VLBI), have a precision better than the milliarcsecond level. Then, we can progress in the knowledge of the global dynamics of the Earth. The goal of my thesis work was to use the Earth gravity field measurements, as well as its variations, as a tool to improve the Earth orientation modelisation. On the one hand, in order to use the future GRACE measurements, that are announced to be more precise than ever, we investigated precise comparisons between the numerical methods of Cowell and Encke for orbit integration, into the GRGS software (i.e. GINS). On the other hand, we developed the theoretical links between the Earth Orientation Parameters (EOP) and the temporal variations of the gravity field. Then, we used the temporal variations data of the geopotential degree 2 coefficients, in order to investigate their influence on the length of day, the polar motion, and the precession of the equator.
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https://tel.archives-ouvertes.fr/tel-00008286
Contributor : Géraldine Bourda <>
Submitted on : Thursday, January 27, 2005 - 10:38:34 PM
Last modification on : Monday, December 14, 2020 - 9:45:45 AM
Long-term archiving on: : Friday, September 14, 2012 - 10:31:02 AM

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  • HAL Id : tel-00008286, version 1

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G. Bourda. Rotation terrestre et Variations du champ de gravité : Etude et apport des missions CHAMP et GRACE. Sciences de la Terre. Observatoire de Paris, 2004. Français. ⟨tel-00008286⟩

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