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Wavelet modeling of the gravity field over Japan / Isabelle Panet in Bulletin of the Geographical survey institute, vol 57 (December 2009)
[article]
Titre : Wavelet modeling of the gravity field over Japan Type de document : Article/Communication Auteurs : Isabelle Panet , Auteur ; Yuki Kuroishi, Auteur ; Matthias Holschneider, Auteur Année de publication : 2009 Article en page(s) : pp 19 - 33 Note générale : Bibliographie
2e partie article : https://www.gsi.go.jp/common/000054750.pdfLangues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique
[Termes IGN] bruit blanc
[Termes IGN] champ de pesanteur local
[Termes IGN] géoïde local
[Termes IGN] harmonique sphérique
[Termes IGN] Japon
[Termes IGN] levé gravimétrique
[Termes IGN] modèle de géopotentiel local
[Termes IGN] ondelette sphérique
[Termes IGN] transformation en ondelettesRésumé : (Auteur) Knowing the geoïd over Japan is essential for many geodetical and geophysical applications. Because of the tectonic settings of the area, significant geoid undulations occur in a wide range of spatial scales and make the determination of the geoïd a complex task. In some applications, high absolute accuracy at long and medium wavelengths is required for geoïd models with high resolution, which can be achieved by a proper combination of satellite gravity information with densely-distributed surface gravity data after careful consideration of their respective error characteristics. Here we show how to realize such a combination in a flexible way using spherical wavelets. The gravity potential is expressed as a linear combination of wavelets, whose coefficients are obtained by a least squares adjustment of the datasets. The combination needs to handle a large system of equations and we apply a domain decomposition method. First, we define sub-domains as subsets of wavelets. Based on the localization properties of the wavelets in space and frequency, we define hierarchical sub-domains of wavelets at different scales. On each scale, blocks of sub-domains are defined by using a tailored spatial splitting of the area. Second, we approximate the normal matrix for each block by introducing local approximation of the wavelets depending on the scale, in which local averages of the data are actually used for computation. Finally, we solve the system iteratively. In the beginning we validate the method with synthetic data, considering two kinds of noise: white noise and colored noise. We then apply the method to data over Japan: a satellite-based geopotential model, EIGEN-GL04S, and a local gravity model from a combination of land and marine gravity data and an altimetry-derived marine gravity model. A hybrid spherical harmonics/wavelet model of the geoïd is obtained at about 15 km resolution and the residuals indicate the existence of possible biases in the surface model. This information is used to correct the local model and the method is repeated with the corrected data, resulting in an improved hybrid model of the gravity field over Japan. Copyright Geographical Survey Institute Numéro de notice : A2009-558 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : sans En ligne : https://www.gsi.go.jp/common/000054749.pdf Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=30187
in Bulletin of the Geographical survey institute > vol 57 (December 2009) . - pp 19 - 33[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 250-09011 RAB Revue Centre de documentation En réserve L003 Disponible Geoid and high resolution sea surface topography modelling in the mediterranean from gravimetry, altimetry and GOCE data: evaluation by simulation / R. Barzaghi in Journal of geodesy, vol 83 n° 8 (August 2009)
[article]
Titre : Geoid and high resolution sea surface topography modelling in the mediterranean from gravimetry, altimetry and GOCE data: evaluation by simulation Type de document : Article/Communication Auteurs : R. Barzaghi, Auteur ; N. Tselfes, Auteur ; I.N. Tziavos, Auteur ; G. Vergos, Auteur Année de publication : 2009 Article en page(s) : pp 751 - 772 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique
[Termes IGN] données altimétriques
[Termes IGN] données GOCE
[Termes IGN] géoïde local
[Termes IGN] hauteurs de mer
[Termes IGN] levé gravimétrique
[Termes IGN] Méditerranée, mer
[Termes IGN] surface de la merRésumé : (Auteur) The determination of local geoid models has traditionally been carried out on land and at sea using gravity anomaly and satellite altimetry data, while it will be aided by the data expected from satellite missions such as those from the Gravity field and steady-state ocean circulation explorer (GOCE). To assess the performance of heterogeneous data combination to local geoid determination, simulated data for the central Mediterranean Sea are analyzed. These data include marine and land gravity anomalies, altimetric sea surface heights, and GOCE observations processed with the space-wise approach. A spectral analysis of the aforementioned data shows their complementary character. GOCE data cover long wavelengths and account for the lack of such information from gravity anomalies. This is exploited for the estimation of local covariance function models, where it is seen that models computed with GOCE data and gravity anomaly empirical covariance functions perform better than models computed without GOCE data. The geoid is estimated by different data combinations and the results show that GOCE data improve the solutions for areas covered poorly with other data types, while also accounting for any long wavelength errors of the adopted reference model that exist even when the ground gravity data are dense. At sea, the altimetric data provide the dominant geoid information. However, the geoid accuracy is sensitive to orbit calibration errors and unmodeled sea surface topography (SST) effects. If such effects are present, the combination of GOCE and gravity anomaly data can improve the geoid accuracy. The present work also presents results from simulations for the recovery of the stationary SST, which show that the combination of geoid heights obtained from a spherical harmonic geopotential model derived from GOCE with satellite altimetry data can provide SST models with some centimeters of error. However, combining data from GOCE with gravity anomalies in a collocation approach can result in the estimation of a higher resolution geoid, more suitable for high resolution mean dynamic SST modeling. Such simulations can be performed toward the development and evaluation of SST recovery methods. Copyright Springer Numéro de notice : A2009-325 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-008-0292-z En ligne : https://doi.org/10.1007/s00190-008-0292-z Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=29955
in Journal of geodesy > vol 83 n° 8 (August 2009) . - pp 751 - 772[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 266-09071 SL Revue Centre de documentation Revues en salle Disponible Gravity gradient modeling using gravity and DEM / L. Zhu in Journal of geodesy, vol 83 n° 6 (June 2009)
[article]
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 limitesRésumé : (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
in Journal of geodesy > vol 83 n° 6 (June 2009) . - pp 557 - 567[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 266-09051 SL Revue Centre de documentation Revues en salle Disponible Relative gravity measurement campaign during the 7th international comparison of absolute gravimeters (2005) / Z. Jiang in Metrologia, vol 46 n° 3 (June 2009)
[article]
Titre : Relative gravity measurement campaign during the 7th international comparison of absolute gravimeters (2005) Type de document : Article/Communication Auteurs : Z. Jiang, Auteur ; Matthias Becker, Auteur ; Olivier Francis, Auteur ; A. Germak, Auteur ; Vojtech Pálinkáš, Auteur ; Philippe Jousset, Auteur ; J. Kostelecky, Auteur ; François Dupont , Auteur ; Chang-Wook Lee, Auteur ; C.L. Tsai, Auteur ; R. Falk, Auteur ; H. Wilmes, Auteur ; A. Kopaev, Auteur ; Laurent Métivier , Auteur ; et al., Auteur Année de publication : 2009 Article en page(s) : pp 214 - 226 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique
[Termes IGN] campagne d'observations
[Termes IGN] gravimètre absolu
[Termes IGN] levé gravimétrique
[Termes IGN] traitement de donnéesRésumé : (auteur) Since the 1st International Comparison of Absolute Gravimeters (ICAG) and accompanying Relative Gravity Campaign (RGC) held at the BIPM in 1981, repeated ICAG-RGCs have been organized every four years. A total of 19 absolute gravimeters (AG) and 15 relative gravimeters (RG) participated in the 7th ICAG-RGC, which took place in 2005. Co-located absolute and relative gravity measurements as well as precision levelling measurements were carried out. The final version of the absolute g values of the 7th ICAG has been officially released recently. This paper is the final report of the 7th RGC and replaces the preliminary results published earlier. It covers the organization of the RGC and the data processing, analyses RG behaviour, computes g, δg and OAG (offset of AG) and discusses their uncertainties. In preparation for the BIPM key comparison ICAG-2009, a standard data-processing procedure has been developed and installed in the BIPM ICAG-RGC software package, GraviSoft. This was used for the final data processing. Numéro de notice : A2009-598 Affiliation des auteurs : LAREG+Ext (1991-2011) Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1088/0026-1394/46/3/008 Date de publication en ligne : 24/03/2009 En ligne : https://doi.org/10.1088/0026-1394/46/3/008 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=102400
in Metrologia > vol 46 n° 3 (June 2009) . - pp 214 - 226[article]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)
[article]
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 terrestreRésumé : (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
in Journal of geodesy > vol 83 n° 6 (June 2009) . - pp 509 - 521[article]Réservation
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