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The first Australian gravimetric quasigeoid model with location-specific uncertainty estimates / Will E. Featherstone in Journal of geodesy, vol 92 n° 2 (February 2018)  

Public [article]  inJournal of geodesy > vol 92 n° 2 (February 2018) . - pp 149 - 168 Titre : The first Australian gravimetric quasigeoid model with location-specific uncertainty estimates Type de document : Article/Communication Auteurs : Will E. Featherstone, Auteur ; Jack C. McCubbine, Auteur ; Nicholas J. Brown, Auteur ; S.J. Claessens, Auteur ; M. S. Filmer, Auteur ; J.F. Kirby, Auteur Année de publication : 2018 Article en page(s) : pp 149 - 168 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique [Termes IGN] Australie [Termes IGN] géoïde gravimétrique [Termes IGN] géoïde local [Termes IGN] propagation d'erreur [Termes IGN] quasi-géoïde Résumé : (Auteur) We describe the computation of the first Australian quasigeoid model to include error estimates as a function of location that have been propagated from uncertainties in the EGM2008 global model, land and altimeter-derived gravity anomalies and terrain corrections. The model has been extended to include Australia’s offshore territories and maritime boundaries using newer datasets comprising an additional ∼280,000 land gravity observations, a newer altimeter-derived marine gravity anomaly grid, and terrain corrections at 1′′×1′′ resolution. The error propagation uses a remove–restore approach, where the EGM2008 quasigeoid and gravity anomaly error grids are augmented by errors propagated through a modified Stokes integral from the errors in the altimeter gravity anomalies, land gravity observations and terrain corrections. The gravimetric quasigeoid errors (one sigma) are 50–60 mm across most of the Australian landmass, increasing to ∼100 mm in regions of steep horizontal gravity gradients or the mountains, and are commensurate with external estimates. Numéro de notice : A2018-059 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-017-1053-7 En ligne : https://doi.org/10.1007/s00190-017-1053-7 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=89392 [article]

A surface spherical harmonic expansion of gravity anomalies on the ellipsoid / S.J. Claessens in Journal of geodesy, vol 89 n° 10 (october 2015)  

Public [article]  inJournal of geodesy > vol 89 n° 10 (october 2015) . - pp 1035 - 1048 Titre : A surface spherical harmonic expansion of gravity anomalies on the ellipsoid Type de document : Article/Communication Auteurs : S.J. Claessens, Auteur ; C. Hirt, Auteur Année de publication : 2015 Article en page(s) : pp 1035 - 1048 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique [Termes IGN] anomalie de pesanteur [Termes IGN] ellipsoïde de référence [Termes IGN] ellipsoïde GRS 1980 [Termes IGN] harmonique sphérique [Termes IGN] transformation Résumé : (auteur) A surface spherical harmonic expansion of gravity anomalies with respect to a geodetic reference ellipsoid can be used to model the global gravity field and reveal its spectral properties. In this paper, a direct and rigorous transformation between solid spherical harmonic coefficients of the Earth’s disturbing potential and surface spherical harmonic coefficients of gravity anomalies in ellipsoidal approximation with respect to a reference ellipsoid is derived. This transformation cannot rigorously be achieved by the Hotine–Jekeli transformation between spherical and ellipsoidal harmonic coefficients. The method derived here is used to create a surface spherical harmonic model of gravity anomalies with respect to the GRS80 ellipsoid from the EGM2008 global gravity model. Internal validation of the model shows a global RMS precision of Numéro de notice : A2015-881 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-015-0832-2 Date de publication en ligne : 17/06/2015 En ligne : https://doi.org/10.1007/s00190-015-0832-2 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=79413 [article]

Variance component estimation uncertainty for unbalanced data: application to a continent-wide vertical datum / M. S. Filmer in Journal of geodesy, vol 88 n° 11 (November 2014)  

Public [article]  inJournal of geodesy > vol 88 n° 11 (November 2014) . - pp 1081-1093 Titre : Variance component estimation uncertainty for unbalanced data: application to a continent-wide vertical datum Type de document : Article/Communication Auteurs : M. S. Filmer, Auteur ; Will E. Featherstone, Auteur ; S.J. Claessens, Auteur Année de publication : 2014 Article en page(s) : pp 1081-1093 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Systèmes de référence et réseaux [Termes IGN] analyse de variance [Termes IGN] continent [Termes IGN] incertitude des données [Termes IGN] système de référence géodésique Résumé : (Auteur) Variance component estimation (VCE) is used to update the stochastic model in least-squares adjustments, but the uncertainty associated with the VCE-derived weights is rarely considered. Unbalanced data is where there is an unequal number of observations in each heterogeneous data set comprising the variance component groups. As a case study using highly unbalanced data, we redefine a continent-wide vertical datum from a combined least-squares adjustment using iterative VCE and its uncertainties to update weights for each data set. These are: (1) a continent-wide levelling network, (2) a model of the ocean’s mean dynamic topography and mean sea level observations, and (3) GPS-derived ellipsoidal heights minus a gravimetric quasigeoid model. VCE uncertainty differs for each observation group in the highly unbalanced data, being dependent on the number of observations in each group. It also changes within each group after each VCE iteration, depending on the magnitude of change for each observation group’s variances. It is recommended that VCE uncertainty is computed for VCE updates to the weight matrix for unbalanced data so that the quality of the updates for each group can be properly assessed. This is particularly important if some groups contain relatively small numbers of observations. VCE uncertainty can also be used as a threshold for ceasing iterations, as it is shown—for this data set at least—that it is not necessary to continue time-consuming iterations to fully converge to unity. Numéro de notice : A2014-564 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-014-0744-6 Date de publication en ligne : 24/07/2014 En ligne : https://doi.org/10.1007/s00190-014-0744-6 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=74750 [article]

Exemplaires(1)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
266-2014111	SL	Revue	Centre de documentation	Revues en salle	Disponible

A synthetic Earth gravity model designed specially for testing regional gravimetric geoid determination algorithms / I. Baran in Journal of geodesy, vol 80 n° 1 (April 2006)  

Public [article]  inJournal of geodesy > vol 80 n° 1 (April 2006) . - pp 1 - 16 Titre : A synthetic Earth gravity model designed specially for testing regional gravimetric geoid determination algorithms Type de document : Article/Communication Auteurs : I. Baran, Auteur ; M. Kuhn, Auteur ; S.J. Claessens, Auteur ; et al., Auteur Année de publication : 2006 Article en page(s) : pp 1 - 16 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique [Termes IGN] Australian Height Datum [Termes IGN] Australie [Termes IGN] champ de pesanteur terrestre [Termes IGN] géoïde gravimétrique [Termes IGN] géoïde local [Termes IGN] géoïde terrestre [Termes IGN] modèle numérique de surface [Termes IGN] nivellement Résumé : (Auteur) A synthetic [simulated] Earth gravity model (SEGM) of the geoid, gravity and topography has been constructed over Australia specifically for validating regional gravimetric geoid determination theories, techniques and computer software. This regional high-resolution (1-arc-min by 1-arc-min) Australian SEGM (AusSEGM) is a combined source and effect model. The long-wavelength effect part (up to and including spherical harmonic degree and order 360) is taken from an assumed errorless EGM96 global geopotential model. Using forward modelling via numerical Newtonian integration, the short-wavelength source part is computed from a high-resolution (3-arc-sec by 3-arc-sec) synthetic digital elevation model (SDEM), which is a fractal surface based on the GLOBE v1 DEM. All topographic masses are modelled with a constant mass-density of 2,670 kg/m3. Based on these input data, gravity values on the synthetic topography (on a grid and at arbitrarily distributed discrete points) and consistent geoidal heights at regular 1-arc-min geographical grid nodes have been computed. The precision of the synthetic gravity and geoid data (after a first iteration) is estimated to be better than 30 u Gal and 3 mm, respectively, which reduces to 1 u Gal and 1 mm after a second iteration. The second iteration accounts for the changes in the geoid due to the superposed synthetic topographic mass distribution. The first iteration of AusSEGM is compared with Australian gravity and GPS-levelling data to verify that it gives a realistic representation of the Earth's gravity field. As a by-product of this comparison, AusSEGM gives further evidence of the north-south-trending error in the Australian Height Datum. The freely available AusSEGM-derived gravity and SDEM data, included as Electronic Supplementary Material (ESM) with this paper, can be used to compute a geoid model that, if correct, will agree to in 3 mm with the AusSEGM geoidal heights, thus offering independent verification of theories and numerical techniques used for regional geoid modelling Numéro de notice : A2006-177 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-005-0002-z En ligne : https://doi.org/10.1007/s00190-005-0002-z Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=27904 [article]

Exemplaires(2)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
266-06031	RAB	Revue	Centre de documentation	En réserve L003	Disponible
266-06032	RAB	Revue	Centre de documentation	En réserve L003	Disponible