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The Iranian height datum offset from the GBVP solution and spirit-leveling/gravimetry data / Amir Ebadi in Journal of geodesy, vol 93 n° 8 (August 2019)  

Public [article]  inJournal of geodesy > vol 93 n° 8 (August 2019) . - pp 1207 - 1225 Titre : The Iranian height datum offset from the GBVP solution and spirit-leveling/gravimetry data Type de document : Article/Communication Auteurs : Amir Ebadi, Auteur ; Alireza A. Ardalan, Auteur ; Roohollah Karimi, Auteur Année de publication : 2019 Article en page(s) : pp 1207 - 1225 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique [Termes descripteurs IGN] analyse de variance [Termes descripteurs IGN] champ de pesanteur terrestre [Termes descripteurs IGN] compensation par moindres carrés [Termes descripteurs IGN] géoïde terrestre [Termes descripteurs IGN] Iran [Termes descripteurs IGN] levé gravimétrique [Termes descripteurs IGN] modèle de géopotentiel [Termes descripteurs IGN] potentiel de pesanteur terrestre [Termes descripteurs IGN] problème des valeurs limites [Termes descripteurs IGN] réseau altimétrique local [Termes descripteurs IGN] réseau altimétrique national Résumé : (auteur) The gravity potential of the zero point of the Iranian height datum (IRHD) is determined as well as the IRHD offset from a global geoid. For this purpose, the geodetic boundary value problem (GBVP) solution based on the remove–compute–restore (RCR) technique is used. In the RCR technique, a global geopotential model (GGM) is required as a reference to remove and restore the long wavelengths of the gravity field. Since the GGMs do not have adequate accuracy over Iran, the IRHD offset is not precisely estimated by the GBVP solution. In this study, aiming to improve the latter, a combination solution based on the GBVP approach and spirit-leveling/gravimetry (LG) data, called the GBVP_LG solution, is proposed. To obtain the GBVP_LG solution, gravity potential obtained from the GBVP solution and the gravity potential differences derived from the LG data are used as two types of observations in a least-squares adjustment. The proper relative weight matrices are determined using the variance component estimation method. To evaluate the proposed method, the gravity potential differences between the start and end points of several check-lines in the leveling network derived from the GBVP and GBVP_LG solutions are compared with those of the LG data. The results show that the dependency of the GBVP_LG solution on the reference model used is much less than that of the GBVP solution. In addition, the results indicate that the GBVP_LG solution has a 42% improvement with respect to the GBVP solution in terms of root-mean-square error. As a result of the GBVP_LG solution, the gravity potential of the IRHD zero point is estimated equal to WIRHD0=62,636,855.89±0.16m2/s2. Therefore, the IRHD offset with respect to the geoid defined by W0=62,636,853.4m2/s2 is obtained equal to −25.4±1.6cm, which means that the IRHD is 25.4 cm below the geoid. Numéro de notice : A2019-385 Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-019-01237-x date de publication en ligne : 12/02/2019 En ligne : https://doi.org/10.1007/s00190-019-01237-x Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=93464 [article]

Deflections of the vertical from full-tensor and single-instrument gravity gradiometry / Christopher Jekeli in Journal of geodesy, vol 93 n° 3 (March 2019)  

Public [article]  inJournal of geodesy > vol 93 n° 3 (March 2019) . - pp 369 - 382 Titre : Deflections of the vertical from full-tensor and single-instrument gravity gradiometry Type de document : Article/Communication Auteurs : Christopher Jekeli, Auteur Année de publication : 2019 Article en page(s) : pp 369 - 382 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique [Termes descripteurs IGN] champ de pesanteur terrestre [Termes descripteurs IGN] déviation de la verticale [Termes descripteurs IGN] faille géologique [Termes descripteurs IGN] gradient de gravitation [Termes descripteurs IGN] intégration de données [Termes descripteurs IGN] levé gravimétrique Résumé : (Auteur) Gravity gradiometry on a moving platform, whether ground or airborne, has the potential to offer an efficient and accurate determination of the deflection of the vertical by simple line integration. A significant error in this process is a trend error that results from the integration of systematic gradient errors. Using an airborne full-tensor gradiometry data set of regularly spaced and intersecting tracks over a 10 km square region and the USDOV2012 vertical deflection model to calibrate these long wavelength errors, it is shown that the gradient-derived deflections agree with the USDOV2012 model at the level of 0.6–0.9 arcsec. Moreover, it is shown by graphical inspection that these differences represent high-frequency signal rather than error. Another data processing technique is examined using only (simulated) single-gradiometer instrument data, i.e., the local differential curvature components, (Γyy−Γxx)/2 and Γxy, of the gravity field. While in theory these data can yield deflection components using two parallel data tracks, the results in the tested case are unsatisfactory due to implicit additional cross-track integration errors that accumulate systematically. The analysis thus demonstrates the importance of using the individual horizontal gradient components, Γxx, Γyy, to derive the deflection of the vertical. Numéro de notice : A2019-152 Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-018-1162-y date de publication en ligne : 11/07/2018 En ligne : https://doi.org/10.1007/s00190-018-1162-y Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=92491 [article]

Evaluation of terrestrial and airborne gravity data over Antarctica : a generic approach / P. Zingerle in Journal of geodetic science, vol 9 n° 1 (January 2019)  

Public [article]  inJournal of geodetic science > vol 9 n° 1 (January 2019) . - pp 29 - 40 Titre : Evaluation of terrestrial and airborne gravity data over Antarctica : a generic approach Type de document : Article/Communication Auteurs : P. Zingerle, Auteur ; Roland Pail, Auteur ; M. Scheinert, Auteur ; T. Schaller, Auteur Année de publication : 2019 Article en page(s) : pp 29 - 40 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique [Termes descripteurs IGN] Antarctique [Termes descripteurs IGN] champ de pesanteur terrestre [Termes descripteurs IGN] données localisées 3D [Termes descripteurs IGN] levé gravimétrique [Termes descripteurs IGN] modèle de géopotentiel Résumé : (auteur) The AntGrav project, funded by the German Research Foundation (DFG) has the main objective to homogenize and optimize Antarctic gravity field information. Within this project an evaluation procedure is needed to inspect all different kind of gravity field surveys available in Antarctica. In this paper a suitable methodology is proposed. We present an approach for fast 3D gravity point data reduction in different spectral bands. This is achieved through pre-calculating a fine 3D mesh of synthesized gravity functionals over the entirety of the Antarctic continent, for which two different global models are used: the combined satellite model GOCO05s for the long-wavelength part, and the topographic model Earth2014 for the shorter wavelengths. To maximize the applicability separate meshes are calculated for different spectral bands in order to specifically reduce a certain band or a selected combination. All meshes are calculated for gravity anomalies as well as gravity disturbances. Utilizing these meshes, synthesized gravity data at arbitrary positions is computed by conventional 3D interpolation methods (e.g. linear, cubic or spline). It is shown that the applied approach can reach a worst-case interpolation error of less than 1 mGal. Evaluation results are presented for the AntGG grid and exemplary for the in-situ measurements of the AGAP and BAS-LAND campaigns. While general properties, large-scale errors and systematic effects can usually be detected, small-scale errors (e.g. of single points) are mostly untraceable due to the uncertainties within the topographic model. Numéro de notice : A2019-408 Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1515/jogs-2019-0004 date de publication en ligne : 19/08/2019 En ligne : https://doi.org/10.1515/jogs-2019-0004 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=93526 [article]

An analysis of gravitational gradients in rotated frames and their relation to oriented mass sources / Isabelle Panet in Journal of geophysical research : Solid Earth, vol 123 n° 12 (December 2018)  

Public [article]  inJournal of geophysical research : Solid Earth > vol 123 n° 12 (December 2018) . - pp 11062 -11090 Titre : An analysis of gravitational gradients in rotated frames and their relation to oriented mass sources Type de document : Article/Communication Auteurs : Isabelle Panet , Auteur Année de publication : 2018 Article en page(s) : pp 11062 -11090 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique [Termes descripteurs IGN] analyse de sensibilité [Termes descripteurs IGN] champ de pesanteur terrestre [Termes descripteurs IGN] gradient de gravitation [Termes descripteurs IGN] levé gravimétrique [Termes descripteurs IGN] masse de la Terre [Termes descripteurs IGN] modèle de géopotentiel [Termes descripteurs IGN] repère de référence Résumé : (auteur) Many mass sources within the Earth and its fluid envelopes show elongated geometries, aligning with the orientations of plate boundaries and plate motions, coastlines, rivers, and drainage basins for instance. To enhance their identification and separation in global or regional gravity observations and models, a dedicated method based on gravitational gradients analysis is presented here. This approach provides a detailed description of the geographic pattern of the gravity variations, which are accurately mapped thanks to the regular spatial coverage of high‐accuracy satellite data and arise from lateral density changes within the planet. First, gravity gradients are defined at different spatial scales in spherical frames, which are rotated along the radial axis according to the orientation of the source. The sensitivity of these gradients to the mass distribution inside a spherical Earth is described and analytical expressions relating the source to the observable are introduced. Then, the gravity gradients responses at different spatial scales to flat, elementary mass sources located at the surface and at increasing depth are studied. Specifically, the paper investigates how a source width and orientation can be determined, for localized and oscillatory mass anomalies with different width‐to‐length aspect ratios. This theoretical case study aims at providing a basis for the analysis of more complex mass structures, when applying the presented method to static or time‐varying satellite gravity field models. It may help deciphering the nature of the gravity sources by the detection of meaningful geometries and orientations in the gravity field. Numéro de notice : A2018-655 Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1029/2018JB016717 date de publication en ligne : 05/12/2018 En ligne : https://doi.org/10.1029/2018JB016717 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=93520 [article]

A Terrestrial Reference Frame realised on the observation level using a GPS-LEO satellite constellation / Daniel Koenig in Journal of geodesy, vol 92 n° 11 (November 2018)  

Public [article]  inJournal of geodesy > vol 92 n° 11 (November 2018) . - pp 1299 - 1312 Titre : A Terrestrial Reference Frame realised on the observation level using a GPS-LEO satellite constellation Type de document : Article/Communication Auteurs : Daniel Koenig, Auteur Année de publication : 2018 Article en page(s) : pp 1299 - 1312 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Systèmes de référence et réseaux [Termes descripteurs IGN] champ de pesanteur terrestre [Termes descripteurs IGN] données GPS [Termes descripteurs IGN] données GRACE [Termes descripteurs IGN] géocentre [Termes descripteurs IGN] International Terrestrial Reference Frame [Termes descripteurs IGN] transformation de Helmert Résumé : (Auteur) Applying a one-step integrated process, i.e. by simultaneously processing all data and determining all satellite orbits involved, a Terrestrial Reference Frame (TRF) consisting of a geometric as well as a dynamic part has been determined at the observation level using the EPOS-OC software of Deutsches GeoForschungsZentrum. The satellite systems involved comprise the Global Positioning System (GPS) as well as the twin GRACE spacecrafts. Applying a novel approach, the inherent datum defect has been overcome empirically. In order not to rely on theoretical assumptions this is done by carrying out the TRF estimation based on simulated observations and using the associated satellite orbits as background truth. The datum defect is identified here as the total of all three translations as well as the rotation about the z-axis of the ground station network leading to a rank-deficient estimation problem. To rectify this singularity, datum constraints comprising no-net translation (NNT) conditions in x, y, and z as well as a no-net rotation (NNR) condition about the z-axis are imposed. Thus minimally constrained, the TRF solution covers a time span of roughly a year with daily resolution. For the geometric part the focus is put on Helmert transformations between the a priori and the estimated sets of ground station positions, and the dynamic part is represented by gravity field coefficients of degree one and two. The results of a reference solution reveal the TRF parameters to be estimated reliably with high precision. Moreover, carrying out a comparable two-step approach using the same data and models leads to parameters and observational residuals of worse quality. A validation w.r.t. external sources shows the dynamic origin to coincide at a level of 5 mm or better in x and y, and mostly better than 15 mm in z. Comparing the derived GPS orbits to IGS final orbits as well as analysing the SLR residuals for the GRACE satellites reveals an orbit quality on the few cm level. Additional TRF test solutions demonstrate that K-Band Range-Rate observations between both GRACE spacecrafts are crucial for accurately estimating the dynamic frame’s orientation, and reveal the importance of the NNT- and NNR-conditions imposed for estimating the components of the dynamic geocenter. Numéro de notice : A2018-464 Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-018-1121-7 date de publication en ligne : 27/02/2018 En ligne : https://doi.org/10.1007/s00190-018-1121-7 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=91063 [article]

Least-squares cross-wavelet analysis and its applications in geophysical time series / Ebrahim Ghaderpour in Journal of geodesy, vol 92 n° 10 (October 2018)  

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Migrating pattern of deformation prior to the Tohoku-Oki earthquake revealed by GRACE data / Isabelle Panet in Nature geoscience, vol 11 n° 5 (May 2018)  

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High performance clocks and gravity field determination / J. Muller in Space Science Reviews, vol 214 n° 1 (February 2018)  

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Détermination d’un modèle géopotentiel à haute résolution en zone littorale aidé par des mesures d’horloges atomiques / Hugo Lecomte (2018) 

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Multi-scale modeling of Earth's gravity field in space and time / Shuo Wang in Journal of geodynamics, vol 106 (May 2017)  

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Gravity forward modeling with a tesseroid-based rock-water-ice approach / Thomas Grombein (2017)    

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Effects of space weather on GOCE electrostatic gravity gradiometer measurements / Elmas Sinem Ince in Journal of geodesy, vol 90 n° 12 (December 2016)  

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On the spectral combination of satellite gravity model, terrestrial and airborne gravity data for local gravimetric geoid computation / Tao Jian in Journal of geodesy, vol 90 n° 12 (December 2016)  

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On the usefulness of relativistic space-times for the description of the Earth’s gravitational field / Michael Soffel in Journal of geodesy, vol 90 n° 12 (December 2016)  

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A conventional value for the geoid reference potential W0 / L. Sánchez in Journal of geodesy, vol 90 n° 9 (September 2016)  

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