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The combination of GNSS-levelling data and gravimetric (quasi-) geoid heights in the presence of noise / R. Klees in Journal of geodesy, vol 84 n° 12 (December 2010)
[article]
Titre : The combination of GNSS-levelling data and gravimetric (quasi-) geoid heights in the presence of noise Type de document : Article/Communication Auteurs : R. Klees, Auteur ; I. Prutkin, Auteur Année de publication : 2010 Article en page(s) : pp 731 - 749 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique
[Termes IGN] altitude normale
[Termes IGN] altitude orthométrique
[Termes IGN] bruit (théorie du signal)
[Termes IGN] champ de pesanteur local
[Termes IGN] collocation par moindres carrés
[Termes IGN] données GNSS
[Termes IGN] géoïde gravimétrique
[Termes IGN] hauteur ellipsoïdale
[Termes IGN] matrice de covariance
[Termes IGN] nivellement par GPS
[Termes IGN] problème des valeurs limites
[Termes IGN] Suisse
[Termes IGN] varianceRésumé : (Auteur) We propose a methodology for the combination of a gravimetric (quasi-) geoid with GNSS-levelling data in the presence of noise with correlations and/or spatially varying noise variances. It comprises two steps: first, a gravimetric (quasi-) geoid is computed using the available gravity data, which, in a second step, is improved using ellipsoidal heights at benchmarks provided by GNSS once they have become available. The methodology is an alternative to the integrated processing of all available data using least-squares techniques or least-squares collocation. Unlike the corrector-surface approach, the pursued approach guarantees that the corrections applied to the gravimetric (quasi-) geoid are consistent with the gravity anomaly data set. The methodology is applied to a data set comprising 109 gravimetric quasi-geoid heights, ellipsoidal heights and normal heights at benchmarks in Switzerland. Each data set is complemented by a full noise covariance matrix. We show that when neglecting noise correlations and/or spatially varying noise variances, errors up to 10% of the differences between geometric and gravimetric quasi-geoid heights are introduced. This suggests that if high-quality ellipsoidal heights at benchmarks are available and are used to compute an improved (quasi-) geoid, noise covariance matrices referring to the same datum should be used in the data processing whenever they are available. We compare the methodology with the corrector-surface approach using various corrector surface models. We show that the commonly used corrector surfaces fail to model the more complicated spatial patterns of differences between geometric and gravimetric quasi-geoid heights present in the data set. More flexible parametric models such as radial basis function approximations or minimum-curvature harmonic splines perform better. We also compare the proposed method with generalized least-squares collocation, which comprises a deterministic trend model, a random signal component and a random correlated noise component. Trend model parameters and signal covariance function parameters are estimated iteratively from the data using non-linear least-squares techniques. We show that the performance of generalized least-squares collocation is better than the performance of corrector surfaces, but the differences with respect to the proposed method are still significant. Numéro de notice : A2010-559 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-010-0406-2 Date de publication en ligne : 29/08/2010 En ligne : https://doi.org/10.1007/s00190-010-0406-2 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=30751
in Journal of geodesy > vol 84 n° 12 (December 2010) . - pp 731 - 749[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 266-02010121 SL Revue Centre de documentation Revues en salle Disponible 266-2010121 SL Revue Centre de documentation Revues en salle Disponible A comparison of recent Earth gravitational models with emphasis on their contribution in refining the gravity and geoid at continental or regional scale / D. Arabelos in Journal of geodesy, vol 84 n° 11 (November 2010)
[article]
Titre : A comparison of recent Earth gravitational models with emphasis on their contribution in refining the gravity and geoid at continental or regional scale Type de document : Article/Communication Auteurs : D. Arabelos, Auteur ; C.C. Tscherning, Auteur Année de publication : 2010 Article en page(s) : pp 643 - 660 Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique
[Termes IGN] analyse comparative
[Termes IGN] champ de pesanteur local
[Termes IGN] champ de pesanteur terrestre
[Termes IGN] covariance
[Termes IGN] données GRACE
[Termes IGN] Earth Gravity Model 1996
[Termes IGN] Earth Gravity Model 2008
[Termes IGN] géoïde terrestreRésumé : (Auteur) Since the publication of the Earth gravitational model (EGM) 96 considerable improvements in the observation techniques resulted in the development of new improved models. The improvements are due to the availability of data from dedicated gravity mapping missions (CHAMP, GRACE) and to the use of 5? * 5? terrestrial and altimetry derived gravity anomalies. It is expected that the use of new EGMs will further contribute to the improvement of the resolution and accuracy of the gravity and geoid modeling in continental and regional scale. To prove this numerically, three representative Earth gravitational models are used for the reduction of several kinds of data related to the gravity field in different places of the Earth. The results of the reduction are discussed regarding the corresponding covariance functions which might be used for modeling using the least squares collocation method. The contribution of the EIGEN-GL04C model in most cases is comparable to that of EGM96. However, the big difference is shown in the case of EGM2008, due not only to its quality but obviously to its high degree of expansion. Almost in all cases the variance and the correlation length of the covariance functions of data reduced to this model up to its maximum degree are only a few percentages of corresponding quantities of the same data reduced up to degree 360. Furthermore, the mean value and the standard deviation of the reduced gravity anomalies in extended areas of the Earth such as Australia, Arctic region, Scandinavia or the Canadian plains, vary between -1 and +1 and between 5 and 10 * 10-5 ms-2, respectively, reflecting the homogenization of the gravity field on a regional scale. This is very important in using least squares collocation for regional applications. However, the distance to the first zero-value was in several cases much longer than warranted by the high degree of the expansion. This is attributed to errors of medium wavelengths stemming from the lack of, e.g., high-quality data in some area. Numéro de notice : A2010-476 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-010-0397-z Date de publication en ligne : 15/09/2010 En ligne : https://doi.org/10.1007/s00190-010-0397-z Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=30669
in Journal of geodesy > vol 84 n° 11 (November 2010) . - pp 643 - 660[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 266-2010111 SL Revue Centre de documentation Revues en salle Disponible Evaluating terrestrial water storage variations from regionally constrained GRACE mascon data and hydrological models over Southern Africa: preliminary results / P. Krogh in International Journal of Remote Sensing IJRS, vol 31 n° 14 (July 2010)
[article]
Titre : Evaluating terrestrial water storage variations from regionally constrained GRACE mascon data and hydrological models over Southern Africa: preliminary results Type de document : Article/Communication Auteurs : P. Krogh, Auteur ; O. Andersen, Auteur ; C. Michailovsky, Auteur ; et al., Auteur Année de publication : 2010 Article en page(s) : pp 3899 - 3912 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale
[Termes IGN] Afrique du sud (état)
[Termes IGN] champ de pesanteur local
[Termes IGN] données GRACE
[Termes IGN] Malawi
[Termes IGN] modèle hydrographique
[Termes IGN] ressources en eau
[Termes IGN] variable régionalisée
[Termes IGN] variationRésumé : (Auteur) A concentration of surface mass has a distinct, localized signature in Gravity Recovery and Climate Experiment (GRACE) K-band range rate (KBRR) data. This fact is exploited in the regional solutions for mass concentration parameters (mascons) made at the Goddard Space Flight Center (GSFC). In this paper we explore an experimental set of regionally constrained mascon blocks over Southern Africa where a system of 1.25° times 1.5° and 1.5° times 1.5° blocks has been designed. The blocks are divided into hydrological regions based on drainage patterns of the largest river basins, and are constrained in different ways. We show that the use of regional constraints, when solving mascon parameters of different hydrological regions independently, yields more detail and variation than comparable spherical harmonic solutions and mascon solutions using isotropic constraints. We validate our results over Lake Malawi with water level from altimetry. Results show that weak constraints across regions in addition to intra-regional constraints are necessary, to reach reasonable mass variations. Numéro de notice : A2010-372 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1080/01431161.2010.483483 En ligne : https://doi.org/10.1080/01431161.2010.483483 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=30566
in International Journal of Remote Sensing IJRS > vol 31 n° 14 (July 2010) . - pp 3899 - 3912[article]Exemplaires (1)
Code-barres Cote Support Localisation Section Disponibilité 080-2010091 RAB Revue Centre de documentation En réserve L003 Exclu du prêt Generation and study of satellite gravity over Gujarat, India and their possible correlation with earthquake occurences / T. Majumba in Geocarto international, vol 25 n° 4 (July 2010)
[article]
Titre : Generation and study of satellite gravity over Gujarat, India and their possible correlation with earthquake occurences Type de document : Article/Communication Auteurs : T. Majumba, Auteur ; R. Bhattacharyya, Auteur Année de publication : 2010 Article en page(s) : pp 269 - 280 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique
[Termes IGN] anomalie de pesanteur
[Termes IGN] champ de pesanteur local
[Termes IGN] corrélation
[Termes IGN] données GRACE
[Termes IGN] épicentre
[Termes IGN] Inde
[Termes IGN] levé gravimétrique
[Termes IGN] risque naturel
[Termes IGN] séismeRésumé : (Auteur) High-resolution satellite gravity data have been generated and utilized to infer subsurface geological structures in the area of devastating earthquake that struck the Bhuj region in Gujarat on 26 January 2001. Latitudinal gravity profiles have been generated in the Bhuj, Anjar and IBF regions across the epicentres (23.5° N, 69.8° E/Mw 7.0 in 2001; 23.2° N, 70° E/Mw 7.0 in 1956; 24.2° N, 69.2° E/Mw 7.8 in 1819). Substantial differences in gravity anomaly patterns as high as 37 mGal could be observed existing near the epicentre regions. These gravitational differences might have caused due to the plate tectonic processes and due to the changes in densities of different lithospheric zones/sedimentary layers. Temporal variations of the satellite-derived gravity and their probable relations with already occurred major earthquakes in this region have been studied. Hence we conclude that drastic changes in gravity anomalies can be considered as a precursor for occurrences of substantially large earthquakes. Numéro de notice : A2010-278 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1080/10106040903486148 Date de publication en ligne : 09/04/2010 En ligne : https://doi.org/10.1080/10106040903486148 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=30472
in Geocarto international > vol 25 n° 4 (July 2010) . - pp 269 - 280[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 059-2010041 RAB Revue Centre de documentation En réserve L003 Disponible Ocean loading effects on the prediction of Antarctic glacial isostatic uplift and gravity rates / K. Simon in Journal of geodesy, vol 84 n° 5 (May 2010)
[article]
Titre : Ocean loading effects on the prediction of Antarctic glacial isostatic uplift and gravity rates Type de document : Article/Communication Auteurs : K. Simon, Auteur ; T. James, Auteur ; Eric Ivins, Auteur Année de publication : 2010 Article en page(s) : pp 305 - 317 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique
[Termes IGN] Antarctique
[Termes IGN] champ de pesanteur local
[Termes IGN] déformation de la croute terrestre
[Termes IGN] données GRACE
[Termes IGN] isostasie
[Termes IGN] positionnement par GPS
[Termes IGN] surcharge océaniqueRésumé : (Auteur) The effect of regional ocean loading on predicted rates of crustal uplift and gravitational change due to glacial isostatic adjustment (GIA) is determined for Antarctica. The effect is found to be significant for the ICE-3G and ICE-5G loading histories (up to -8 mm/year and -3 mm/year change in uplift rate and -3 cm/year and -1 cm/year equivalent water height change (EWHC) of surface mass, respectively). The effect is smaller (+1 mm/year; +0.25 cm/year) for the IJ05 loading history. The impact of ocean loading on the rate of change of the long-wavelength zonal harmonics of the Earth’s gravitational field is also significantly smaller for IJ05 than ICE-3G. A simple analytical formula is derived that is accurate to about 3% in a root-mean-square sense that relates predicted or observed gravitational change at the surface of the Earth (r = a) to the EWHC. A fundamental difference in the definition of the load histories accounts for the differing sensitivities to ocean loading. IJ05 defines its surface load history relative to the present-day surface load, rather than specifying an absolute loading history, and thus implicitly approximates the temporal and spatial mass exchange between grounded ice and open ocean. In contrast, ICE-3G and ICE-5G specify an absolute load history and explicit regional ocean loading substantially perturbs predicted GIA rates. Conclusions of previous studies that used IJ05 predictions without ocean loading are relatively robust. Numéro de notice : A2010-183 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-010-0368-4 Date de publication en ligne : 12/02/2010 En ligne : https://doi.org/10.1007/s00190-010-0368-4 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=30378
in Journal of geodesy > vol 84 n° 5 (May 2010) . - pp 305 - 317[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 266-2010051 SL Revue Centre de documentation Revues en salle Disponible Construction of spherical harmonic series for the potential derivatives of arbitrary orders in the geocentric Earth-fixed reference frame / M. Petrovskaya in Journal of geodesy, vol 84 n° 3 (March 2010)PermalinkSciences of geodesy, vol 1. Advanced and future directions / Guochang Xu (2010)PermalinkWavelet modeling of the gravity field over Japan / Isabelle Panet in Bulletin of the Geographical survey institute, vol 57 (December 2009)PermalinkTriangulated spherical splines for geopotential reconstruction / M.J. Lai in Journal of geodesy, vol 83 n° 8 (August 2009)PermalinkJournées de la recherche IGN 2009 / Anonyme in Géomatique expert, n° 68 (01/04/2009)PermalinkPermalinkPermalinkThe gravitational effect of ocean tide loading at high latitude coastal stations in Norway / D.I. Lysaker in Journal of geodesy, vol 82 n° 9 (September 2008)PermalinkA data-driven approach to local gravity field modelling using spherical radial basis functions / R. Klees in Journal of geodesy, vol 82 n° 8 (August 2008)PermalinkAstronomical-topographic levelling using high-precision astrogeodetic vertical deflections and Digital Terrain Model data / C. Hirt in Journal of geodesy, vol 82 n° 4-5 (April - May 2008)Permalink