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The determination of potential difference by the joint application of measured and synthetical gravity data: a case study in Hungary / G. Papp in Journal of geodesy, vol 83 n° 6 (June 2009)  

Public [article]  inJournal of geodesy > vol 83 n° 6 (June 2009) . - pp 509 - 521 Titre : The determination of potential difference by the joint application of measured and synthetical gravity data: a case study in Hungary Type de document : Article/Communication Auteurs : G. Papp, Auteur ; E. Szeghy, Auteur ; J. Benedek, Auteur Année de publication : 2009 Article en page(s) : pp 509 - 521 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique [Termes IGN] anomalie de Bouguer [Termes IGN] champ de pesanteur terrestre [Termes IGN] distance euclidienne [Termes IGN] Hongrie [Termes IGN] levé gravimétrique [Termes IGN] modèle numérique de terrain [Termes IGN] nivellement [Termes IGN] potentiel de pesanteur terrestre Résumé : (Auteur) In an elementary approach every geometrical height difference between the staff points of a levelling line should have a corresponding average g value for the determination of potential difference in the Earth’s gravity field. In practice this condition requires as many gravity data as the number of staff points if linear variation of g is assumed between them. Because of the expensive fieldwork, the necessary data should be supplied from different sources. This study proposes an alternative solution, which is proved at a test bed located in the Mecsek Mountains, Southwest Hungary, where a detailed gravity survey, as dense as the staff point density (~1 point/34 m), is available along a 4.3-km-long levelling line. In the first part of the paper the effect of point density of gravity data on the accuracy of potential difference is investigated. The average g value is simply derived from two neighbouring g measurements along the levelling line, which are incrementally decimated in the consecutive turns of processing. The results show that the error of the potential difference between the endpoints of the line exceeds 0.1 mm in terms of length unit if the sampling distance is greater than 2 km. Thereafter, a suitable method for the densification of the decimated g measurements is provided. It is based on forward gravity modelling utilising a high-resolution digital terrain model, the normal gravity and the complete Bouguer anomalies. The test shows that the error is only in the order of 10-3mm even if the sampling distance of g measurements is 4 km. As a component of the error sources of levelling, the ambiguity of the levelled height difference which is the Euclidean distance between the inclined equipotential surfaces is also investigated. Although its effect accumulated along the test line is almost zero, it reaches 0.15 mm in a 1-km-long intermediate section of the line. Copyright Springer Numéro de notice : A2009-284 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-008-0257-2 En ligne : https://doi.org/10.1007/s00190-008-0257-2 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=29914 [article]

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Gravity gradient modeling using gravity and DEM / L. Zhu in Journal of geodesy, vol 83 n° 6 (June 2009)  

Public [article]  inJournal of geodesy > vol 83 n° 6 (June 2009) . - pp 557 - 567 Titre : Gravity gradient modeling using gravity and DEM Type de document : Article/Communication Auteurs : L. Zhu, Auteur ; Christopher Jekeli, Auteur Année de publication : 2009 Article en page(s) : pp 557 - 567 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique [Termes IGN] anomalie de pesanteur [Termes IGN] collocation par moindres carrés [Termes IGN] gradient de gravitation [Termes IGN] gravimétrie aérienne [Termes IGN] levé gravimétrique [Termes IGN] modèle de géopotentiel local [Termes IGN] modèle numérique de terrain [Termes IGN] problème des valeurs limites Résumé : (Auteur) A model of the gravity gradient tensor at aircraft altitude is developed from the combination of ground gravity anomaly data and a digital elevation model. The gravity data are processed according to various operational solutions to the boundary-value problem (numerical integration of Stokes’ integral, radial-basis splines, and least-squares collocation). The terrain elevation data are used to reduce free-air anomalies to the geoid and to compute a corresponding indirect effect on the gradients at altitude. We compare the various modeled gradients to airborne gradiometric data and find differences of the order of 10–20 E (SD) for all gradient tensor elements. Our analysis of these differences leads to a conclusion that their source may be primarily measurement error in these particular gradient data. We have thus demonstrated the procedures and the utility of combining ground gravity and elevation data to validate airborne gradiometer systems. Copyright Springer Numéro de notice : A2009-285 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-008-0273-2 En ligne : https://doi.org/10.1007/s00190-008-0273-2 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=29915 [article]

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266-09051	SL	Revue	Centre de documentation	Revues en salle	Disponible

Fitting gravimetric geoid models to vertical deflections / Will E. Featherstone in Journal of geodesy, vol 83 n° 6 (June 2009)  

Public [article]  inJournal of geodesy > vol 83 n° 6 (June 2009) . - pp 583 - 589 Titre : Fitting gravimetric geoid models to vertical deflections Type de document : Article/Communication Auteurs : Will E. Featherstone, Auteur Année de publication : 2009 Article en page(s) : pp 583 - 589 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique [Termes IGN] Australie [Termes IGN] déviation de la verticale [Termes IGN] géoïde gravimétrique [Termes IGN] géoïde local [Termes IGN] pente Résumé : (Auteur) Regional gravimetric geoid and quasigeoid models are now commonly fitted to GPS-levelling data, which simultaneously absorbs levelling, GPS and quasi/geoid errors due to their inseparability. We propose that independent vertical deflections are used instead, which are not affected by this inseparability problem. The formulation is set out for geoid slopes and changes in slopes. Application to 1,080 astrogeodetic deflections over Australia for the AUSGeoid98 model shows that it is feasible, but the poor quality of the historical astrogeodetic deflections led to some unrealistic values. Copyright Springer Numéro de notice : A2009-286 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-008-0263-4 En ligne : https://doi.org/10.1007/s00190-008-0263-4 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=29916 [article]

Exemplaires(1)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
266-09051	SL	Revue	Centre de documentation	Revues en salle	Disponible