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On the improvement of gravimetric geoid undulations and oceanographic dynamic topography though a conbination with satellite altimetry and the application of a modified Kalman filter algorithm / D.A. Smith (1996)

Public Titre : On the improvement of gravimetric geoid undulations and oceanographic dynamic topography though a conbination with satellite altimetry and the application of a modified Kalman filter algorithm Type de document : Monographie Auteurs : D.A. Smith, Auteur Editeur : Colombus (Ohio) : Ohio State University Année de publication : 1996 Collection : Department of Geodetic Science and Surveying Reports num. 436 Importance : 154 p. Format : 21 x 27 cm Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique [Termes IGN] données altimétriques [Termes IGN] équation de Navier-Stokes [Termes IGN] filtre de Kalman [Termes IGN] géoïde gravimétrique [Termes IGN] image ERS [Termes IGN] levé gravimétrique [Termes IGN] océanographie spatiale [Termes IGN] surface de la mer [Termes IGN] TOPEX-Poseidon Index. décimale : 30.41 Géoïde Résumé : (Auteur) This study has investigated a method for combining gravimetric and oceanographic data with satellite altimetry to estimate geoid undulations and oceanographic dynamic topography. The method chosen was a modified Kalman filter, algorithm used to correct pre-calculated grids of undulations and dynamic topography. Approximations to the transition matrix of the dynamic topography required that a stabilization of the Kalman filter be developed to prevent divergence. Data used were TOPEX and ERS-1 altimetry, pre-calculated gravimetric geoid undulations and pre-calculated oceanographic dynamic topography. Evaluation of the dynamic topography data showed a consistently incorrect Gulf Stream location, shape and size. To replace this poor data, a synthetic model was generated from ERS-1 altimetry and an oceanographically calculated mean dynamic topography model. The synthetic data showed good Gulf Stream location, shape and size, though with some systematic disagreement with TOPEX/geoid data. The source of this disagreement was not conclusively determined. Control data were then used to evaluate the stabilization method of the modified Kalman filter. It was shown that divergences due to a poor transition matrix could be eliminated through the new "down-weight" stabilization scheme. Following this, the real data were run through the modified Kalman filter. To estimate the transition matrix for the dynamic topography, a one-layer quasi-geostrophic approximation to the Navier-Stokes' equations was used. Initial runs used varying scale factors for the standard deviations, to help control unrealistic corrections to the a-priori grids. After that, different down-weight factors were investigated for their ability to generate realistic results without divergence. Results of the modified Kalman filter with stabilization showed that filter stability, with realistic results was obtainable, even with the simplified transition matrix approximation. It was concluded that this method will be useful for future applications of combining existing grids of geoid undulations and dynamic topography which are generally calculated from different sources. In addition, a model of oceanographic dynamic topography was shown conclusively to be an unrealistic model of the actual dynamic topography near the Gulf Stream. Numéro de notice : 12109 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Monographie Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=54538

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12109-01	30.41	Livre	Centre de documentation	Géodésie	Disponible

The use of high resolution height data in the computation of high precision geoid undulations on the island of Maui / D.A. Smith (1992)

Public Titre : The use of high resolution height data in the computation of high precision geoid undulations on the island of Maui Type de document : Monographie Auteurs : D.A. Smith, Auteur Editeur : Colombus (Ohio) : Ohio State University Année de publication : 1992 Collection : Department of Geodetic Science and Surveying Reports num. 424 Importance : 69 p. Format : 21 x 27 cm Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique [Termes IGN] géoïde altimétrique [Termes IGN] géoïde local [Termes IGN] Hawaii (Etats-Unis) Index. décimale : 30.41 Géoïde Numéro de notice : 12124 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Monographie Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=54551

Exemplaires(1)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
12124-01	30.41	Livre	Centre de documentation	Géodésie	Disponible