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Global height system unification with GOCE: a simulation study on the indirect bias term in the GBVP approach / C. Gerlach in Journal of geodesy, vol 87 n° 1 (January 2013)
[article]
Titre : Global height system unification with GOCE: a simulation study on the indirect bias term in the GBVP approach Type de document : Article/Communication Auteurs : C. Gerlach, Auteur ; Reiner Rummel, Auteur Année de publication : 2013 Article en page(s) : pp 57 - 67 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique
[Termes IGN] altitude
[Termes IGN] anomalie de pesanteur
[Termes IGN] données GOCE
[Termes IGN] erreur systématique
[Termes IGN] géoïde gravimétrique
[Termes IGN] géoïde terrestre
[Termes IGN] harmonique sphérique
[Termes IGN] hauteur ellipsoïdale
[Termes IGN] modèle de géopotentiel
[Termes IGN] problème des valeurs limites
[Termes IGN] résidu
[Termes IGN] système de référence altimétriqueRésumé : (Auteur) One of the main objectives of ESA’s Gravity Field and Steady-State Ocean Circulation mission GOCE (Gravity field and steady-state ocean circulation mission, 1999) is to allow global unification of height systems by directly providing potential differences between benchmarks in different height datum zones. In other words, GOCE provides a globally consistent and unbiased geoid. If this information is combined with ellipsoidal (derived from geodetic space techniques) and physical heights (derived from leveling/gravimetry) at the same benchmarks, datum offsets between the datum zones can be determined and all zones unified. The expected accuracy of GOCE is around 2–3 cm up to spherical harmonic degree nmax ~ 200. The omission error above this degree amounts to about 30 cm which cannot be neglected. Therefore, terrestrial residual gravity anomalies are necessary to evaluate the medium and short wavelengths of the geoid, i.e. one has to solve the Geodetic Boundary Value Problem (GBVP). The theory of height unification by the GBVP approach is well developed, see e.g. Colombo (A World Vertical Network. Report 296, Department of Geodetic Science and Surveying, 1980) or Rummel and Teunissen (Bull Geod 62:477–498, 1988). Thereby, it must be considered that terrestrial gravity anomalies referring to different datum zones are biased due to the respective datum offsets. Consequently, the height reference surface of a specific datum zone deviates from the unbiased geoid not only due to its own datum offset (direct bias term) but is also indirectly affected by the integration of biased gravity anomalies. The latter effect is called the indirect bias term and it considerably complicates the adjustment model for global height unification. If no satellite based gravity model is employed, this error amounts to about the same size as the datum offsets, i.e. 1–2 m globally. We show that this value decreases if a satellite-only gravity model is used. Specifically for GOCE with nmax ~ 200, the error can be expected not to exceed the level of 1 cm, allowing the effect to be neglected in practical height unification. The results are supported by recent findings by Gatti et al. (J Geod, 2012). Numéro de notice : A2013-074 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-012-0579-y En ligne : https://doi.org/10.1007/s00190-012-0579-y Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=32212
in Journal of geodesy > vol 87 n° 1 (January 2013) . - pp 57 - 67[article]Exemplaires(1)
Code-barres Cote Support Localisation Section Disponibilité 266-2013011 SL Revue Centre de documentation Revues en salle Disponible The height datum problem and the role of satellite gravity models / A. Gatti in Journal of geodesy, vol 87 n° 1 (January 2013)
[article]
Titre : The height datum problem and the role of satellite gravity models Type de document : Article/Communication Auteurs : A. Gatti, Auteur ; M. Reguzzoni, Auteur ; Giovanna Venuti, Auteur Année de publication : 2013 Article en page(s) : pp 15 - 22 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique
[Termes IGN] altitude normale
[Termes IGN] anomalie de pesanteur
[Termes IGN] données GOCE
[Termes IGN] données GRACE
[Termes IGN] Earth Gravity Model 2008
[Termes IGN] erreur en altitude
[Termes IGN] erreur systématique
[Termes IGN] géoïde altimétrique
[Termes IGN] hauteur ellipsoïdale
[Termes IGN] modèle de géopotentiel
[Termes IGN] niveau moyen des mers
[Termes IGN] réseau de nivellement
[Termes IGN] système de référence altimétriqueRésumé : (Auteur) Regional height systems do not refer to a common equipotential surface, such as the geoid. They are usually referred to the mean sea level at a reference tide gauge. As mean sea level varies (by +1 to 2 m) from place to place and from continent to continent each tide gauge has an unknown bias with respect to a common reference surface, whose determination is what the height datum problem is concerned with. This paper deals with this problem, in connection to the availability of satellite gravity missions data. Since biased heights enter into the computation of terrestrial gravity anomalies, which in turn are used for geoid determination, the biases enter as secondary or indirect effect also in such a geoid model. In contrast to terrestrial gravity anomalies, gravity and geoid models derived from satellite gravity missions, and in particular GRACE and GOCE, do not suffer from those inconsistencies. Those models can be regarded as unbiased. After a review of the mathematical formulation of the problem, the paper examines two alternative approaches to its solution. The first one compares the gravity potential coefficients in the range of degrees from 100 to 200 of an unbiased gravity field from GOCE with those of the combined model EGM2008, that in this range is affected by the height biases. This first proposal yields a solution too inaccurate to be useful. The second approach compares height anomalies derived from GNSS ellipsoidal heights and biased normal heights, with anomalies derived from an anomalous potential which combines a satellite-only model up to degree 200 and a high-resolution global model above 200. The point is to show that in this last combination the indirect effects of the height biases are negligible. To this aim, an error budget analysis is performed. The biases of the high frequency part are proved to be irrelevant, so that an accuracy of 5 cm per individual GNSS station is found. This seems to be a promising practical method to solve the problem. Numéro de notice : A2013-070 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-012-0574-3 Date de publication en ligne : 03/07/2012 En ligne : https://doi.org/10.1007/s00190-012-0574-3 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=32208
in Journal of geodesy > vol 87 n° 1 (January 2013) . - pp 15 - 22[article]Exemplaires(1)
Code-barres Cote Support Localisation Section Disponibilité 266-2013011 SL Revue Centre de documentation Revues en salle Disponible New constraints on the origin of the Hawaiian swell from wavelet analysis of the geoid-to-topography ratio / Cécilia Cadio in Earth and planetary science letters, vol 359–360 (15 December 2012)
[article]
Titre : New constraints on the origin of the Hawaiian swell from wavelet analysis of the geoid-to-topography ratio Type de document : Article/Communication Auteurs : Cécilia Cadio, Auteur ; Maxim D. Ballmer, Auteur ; Isabelle Panet , Auteur ; Michel Diament , Auteur ; Neil Ribe, Auteur Année de publication : 2012 Article en page(s) : pp 40 - 54 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale
[Termes IGN] anomalie de pesanteur
[Termes IGN] convection
[Termes IGN] géoïde local
[Termes IGN] Hawaii (Etats-Unis)
[Termes IGN] houle
[Termes IGN] lithosphère
[Termes IGN] ondelette
[Termes IGN] transformation en ondelettes
[Termes IGN] volcanRésumé : (Auteur) Analyzing the formation mechanism of hotspot swells enhances our understanding of intraplate volcanism and the underlying geodynamical processes. The two main hypotheses for the origin of the archetypal Hawaiian swell are thermal lithospheric thinning, and dynamic support by an ascending plume. Any successful model would have to be able to simultaneously explain the swell topography and the corresponding geoid anomaly. In simple models of isostatic compensation, the geoid-to-topography ratio (GTR) is linearly related to the depth of the compensating mass; therefore it is often considered a fundamental parameter to assess swell support mechanisms. Previous estimates for the geoid-to-topography ratio (GTR) of the Hawaiian swell however are biased towards low values by incomplete removal of the effects of volcanic loading and lithospheric flexure. In order to resolve these issues, we here apply a continuous wavelet transform, which allows resolution of lateral variations of the GTR at various spatial scales. In a series of synthetic tests, the robustness of this approach and its power to identify the origin of hotspot swells are established. With 8 m/km on the youngest part of the chain, the recovered GTR agrees well with the predictions for dynamic support, therefore ruling out thermal rejuvenation as an important mechanism. We also find that the depth of the compensating mass decays by 20 km over a distance of 500 km from Hawaii to Kauai, and identify sublithospheric erosion by small-scale convection in the ponded plume material as a viable mechanism to support this decay. Numéro de notice : A2012-740 Affiliation des auteurs : LAREG+Ext (1991-2011) Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.epsl.2012.10.006 Date de publication en ligne : 05/11/2012 En ligne : https://doi.org/10.1016/j.epsl.2012.10.006 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=91475
in Earth and planetary science letters > vol 359–360 (15 December 2012) . - pp 40 - 54[article]Wavelet‐based directional analysis of the gravity field : evidence for large‐scale undulations / M. Hayn in Geophysical journal international, vol 189 n° 3 (June 2012)
[article]
Titre : Wavelet‐based directional analysis of the gravity field : evidence for large‐scale undulations Type de document : Article/Communication Auteurs : M. Hayn, Auteur ; Isabelle Panet , Auteur ; Michel Diament , Auteur ; Matthias Holschneider, Auteur ; Mioara Mandea, Auteur ; Anne Davaille Année de publication : 2012 Article en page(s) : pp 1430 - 1456 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique
[Termes IGN] anomalie de pesanteur
[Termes IGN] données GRACE
[Termes IGN] manteau terrestre
[Termes IGN] modèle de géopotentiel
[Termes IGN] ondelette d'Abel-Poisson
[Termes IGN] Pacifique (océan)
[Termes IGN] subduction
[Termes IGN] transformation en ondelettesRésumé : (Auteur) In the eighties, the analysis of satellite altimetry data leads to the major discovery of gravity lineations in the oceans, with wavelengths between 200 and 1400 km. While the existence of the 200 km scale undulations is widely accepted, undulations at scales larger than 400 km are still a matter of debate. In this paper, we revisit the topic of the large‐scale geoid undulations over the oceans in the light of the satellite gravity data provided by the GRACE mission, considerably more precise than the altimetry data at wavelengths larger than 400 km.
First, we develop a dedicated method of directional Poisson wavelet analysis on the sphere with significance testing, in order to detect and characterize directional structures in geophysical data on the sphere at different spatial scales. This method is particularly well suited for potential field analysis. We validate it on a series of synthetic tests, and then apply it to analyze recent gravity models, as well as a bathymetry data set independent from gravity. Our analysis confirms the existence of gravity undulations at large scale in the oceans, with characteristic scales between 600 and 2000 km. Their direction correlates well with present‐day plate motion over the Pacific ocean, where they are particularly clear, and associated with a conjugate direction at 1500 km scale. A major finding is that the 2000 km scale geoid undulations dominate and had never been so clearly observed previously. This is due to the great precision of GRACE data at those wavelengths. Given the large scale of these undulations, they are most likely related to mantle processes. Taking into account observations and models from other geophysical information, as seismological tomography, convection and geochemical models and electrical conductivity in the mantle, we conceive that all these inputs indicate a directional fabric of the mantle flows at depth, reflecting how the history of subduction influences the organization of lower mantle upwellings.Numéro de notice : A2012-742 Affiliation des auteurs : LAREG+Ext (1991-2011) Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1111/j.1365-246X.2012.05455.x Date de publication en ligne : 19/04/2012 En ligne : https://doi.org/10.1111/j.1365-246X.2012.05455.x Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=91491
in Geophysical journal international > vol 189 n° 3 (June 2012) . - pp 1430 - 1456[article]
Titre : Auvergne dataset: Testing several geoid computation methods Type de document : Article/Communication Auteurs : Pierre Valty , Auteur ; Henri Duquenne (1948-2010) , Auteur ; Isabelle Panet , Auteur Editeur : Berlin, Heidelberg, Vienne, New York, ... : Springer Année de publication : 2012 Collection : International Association of Geodesy Symposia, ISSN 0939-9585 num. 136 Conférence : IAG 2009 Symposium, Geodesy for Planet Earth 31/08/2009 04/09/2009 Buenos Aires Argentine Proceedings Springer Importance : pp 465 - 472 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique
[Termes IGN] altitude
[Termes IGN] analyse de données
[Termes IGN] anomalie de pesanteur
[Termes IGN] Auvergne
[Termes IGN] formule de Stokes
[Termes IGN] levé gravimétrique
[Termes IGN] quasi-géoïdeRésumé : (auteur) In 2004, the French Institut Géographique National (IGN), upon the request of the steering committee of the European Gravity and Geoid Project, prepared a dataset to test geoid computation methods. It consists of a set of about 240,000 gravity points, three digital terrestrial models (an accurate one, a low-resolution one and a filtered one) and 75 GPS/levelling points to evaluate the quality of the computed geoid models (Duquenne, A data set to test geoid computation methods. In: Dergisi H (eds.), Proceedings of the 1st international symposium of the international gravity field service “gravity field of the earth”, pp 61–65, 2006). In this paper, we compared the following geoid computation methods using the Auvergne dataset: the remove-compute-restore method using the unmodified Stokes’ kernel, the deterministic (Wong and Gore) and stochastic (KTH) modifications of Stokes’ kernel. For each method, we tested different choices of the parameters (radius of integration of Stokes’ anomalies, degree of modification of Stokes’ kernel, radius of integration of terrain effect, etc.). We analysed the results in order to find out which method performs the best and how the geoid modelling method impacts the results, considering the presence of errors in the dataset. The question that this work intends to answer is whether we should put our efforts rather on the theoretical investigations of geoid modelling methodologies, or on the acquisition of gravity measurements. Numéro de notice : C2009-032 Affiliation des auteurs : LAREG (1991-2011) Thématique : POSITIONNEMENT Nature : Communication nature-HAL : ComAvecCL&ActesPubliésIntl DOI : 10.1007/978-3-642-20338-1_56 Date de publication en ligne : 16/07/2011 En ligne : https://doi.org/10.1007/978-3-642-20338-1_56 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=91509 GRACE-derived surface water mass anomalies by energy integral approach: application to continental hydrology / Guillaume Ramillien in Journal of geodesy, vol 85 n° 6 (June 2011)PermalinkPacific geoid anomalies revisited in light of thermochemical oscillating domes in the lower mantle / Cécilia Cadio in Earth and planetary science letters, vol 306 n° 1-2 (June 2011)PermalinkGeneration 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)PermalinkCan mean values of Helmert's gravity anomalies be continued downward directly? / Petr Vanicek in Geomatica, vol 64 n° 2 (June 2010)PermalinkSea surface topography and marine geoid by airborne laser altimetry and shipborne ultrasound altimetry / Philippe Limpach (2010)PermalinkClassical globally reflected gravity field determination in modern locally oriented multiscale framework / W. Freeden in Journal of geodesy, vol 83 n° 12 (December 2009)PermalinkUsing gravity and topography-implied anomalies to assess data requirements for precise geoid computation / Christopher Jekeli in Journal of geodesy, vol 83 n° 12 (December 2009)PermalinkDétermination du géoïde gravimétrique au nord de l'Algérie : méthodes de Stokes-Helmert / N. Zekkour in Bulletin des sciences géographiques, n° 24 (Septembre 2009)PermalinkGravity gradient modeling using gravity and DEM / L. Zhu in Journal of geodesy, vol 83 n° 6 (June 2009)PermalinkThe 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)Permalink