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Apports des données gravimétriques GRACE pour l'assimilation de données altimétriques et in-situ dans un modèle de l'Océan Pacifique Tropical.

Abstract : The objective of this work is to evaluate the contribution of a Mean Dynamic Topography (MDT) deduced from the GRACE gravimetric data, in order to reconstruct the Tropical Pacific Ocean circulation via data assimilation.
Recent advances in our knowledge of the geoid have driven us to investigate the impact of using a fully observed absolute altimetric signal. The OPA model of the Tropical Pacific Ocean, where in-situ and quasi-synoptic data are available (TAO array), and a reduced order Kalman filter (SEEK) have been developed and used under different configurations. The first one assumes a pre-GRACE situation using an artificial MDT from the model itself, while the second one uses a fully observed MDT computed with the GRACE geoid. TAO temperature profiles are jointly assimilated into the model.
This work points out the importance of the mean reference reliability to assimilate sea level anomaly. The main result concerns the improved ability of the assimilation system using GRACE to deal with both satellite and in-situ observations. The joint assimilation of altimetry and TAO data is more efficient thanks to a better compatibility brought by the use of GRACE data.
Furthermore, a physical analysis has been conducted, considering the data assimilation contribution on the simulated dynamics of the Tropical Pacific Ocean. This work specifically aims at illustrating how data assimilation can contribute to improve our understanding of the wide amount of physical mechanisms driving the ocean dynamics in this region.
Interestingly and retrospectively, this analysis also reveals an area (along 8°N) where the GRACE data may have a limitation that should be fixed.
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https://tel.archives-ouvertes.fr/tel-00138506
Contributor : Frédéric Castruccio <>
Submitted on : Thursday, June 14, 2007 - 3:33:47 PM
Last modification on : Thursday, November 19, 2020 - 3:54:10 PM
Long-term archiving on: : Thursday, September 23, 2010 - 4:06:11 PM

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  • HAL Id : tel-00138506, version 3

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Frédéric Castruccio. Apports des données gravimétriques GRACE pour l'assimilation de données altimétriques et in-situ dans un modèle de l'Océan Pacifique Tropical.. Océan, Atmosphère. Université Joseph-Fourier - Grenoble I, 2006. Français. ⟨tel-00138506v3⟩

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