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The AUSGeoid09 model of the Australian Height Datum / Will E. Featherstone in Journal of geodesy, vol 85 n° 3 (March 2011)  

Public [article]  inJournal of geodesy > vol 85 n° 3 (March 2011) . - pp 133 - 150 Titre : The AUSGeoid09 model of the Australian Height Datum Type de document : Article/Communication Auteurs : Will E. Featherstone, Auteur ; J.F. Kirby, Auteur ; C. Hirt, Auteur ; M. Filmer, Auteur ; et al., Auteur Année de publication : 2011 Article en page(s) : pp 133 - 150 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Systèmes de référence et réseaux [Termes IGN] Australian Height Datum [Termes IGN] Australie [Termes IGN] géoïde local [Termes IGN] positionnement par GNSS Résumé : (Auteur) AUSGeoid09 is the new Australia-wide gravimetric quasigeoid model that has been a posteriori fitted to the Australian Height Datum (AHD) so as to provide a product that is practically useful for the more direct determination of AHD heights from Global Navigation Satellite Systems (GNSS). This approach is necessary because the AHD is predominantly a third-order vertical datum that contains a ~1 m north-south tilt and ~0.5 m regional distortions with respect to the quasigeoid, meaning that GNSS-gravimetric-quasigeoid and AHD heights are inconsistent. Because the AHD remains the official vertical datum in Australia, it is necessary to provide GNSS users with effective means of recovering AHD heights. The gravimetric component of the quasigeoid model was computed using a hybrid of the remove-compute-restore technique with a degree-40 deterministically modified kernel over a one-degree spherical cap, which is superior to the remove-compute-restore technique alone in Australia (with or without a cap). This is because the modified kernel and cap combine to filter long-wavelength errors from the terrestrial gravity anomalies. The zero-tide EGM2008 global gravitational model to degree 2,190 was used as the reference field. Other input data are ~1.4 million land gravity anomalies from Geoscience Australia, 1' x ' DNSC2008GRA altimeter-derived gravity anomalies offshore, the 9"x 9" GEODATA-DEM9S Australian digital elevation model, and a readjustment of Australian National Levelling Network (ANLN) constrained to the CARS2006 mean dynamic ocean topography model. To determine the numerical integration parameters for the modified kernel, the gravimetric component of AUSGeoid09 was compared with 911 GNSS-observed ellipsoidal heights at benchmarks. The standard deviation of fit to the GNSS-AHD heights is + 222 mm, which dropped to + 134 mm for the readjusted GNSS-ANLN heights showing that careful consideration now needs to be given to the quality of the levelling data used to assess gravimetric quasigeoid models. The publicly released version of AUSGeoid09 also includes a geometric component that models the difference between the gravimetric quasigeoid and the zero surface of the AHD at 6,794 benchmarks. This a posteriori fitting used least-squares collocation (LSC) in cross-validation mode to determine a correlation length of 75 km for the analytical covariance function, whereas the noise was taken from the estimated standard deviation of the GNSS ellipsoidal heights. After this LSC surface fitting, the standard deviation of fit reduced to + 30 mm, one-third of which is attributable to the uncertainty in the GNSS ellipsoidal heights. Numéro de notice : A2011-163 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-010-0422-2 Date de publication en ligne : 19/11/2010 En ligne : https://doi.org/10.1007/s00190-010-0422-2 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=30941 [article]

Exemplaires(1)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
266-2011031	RAB	Revue	Centre de documentation	En réserve L003	Disponible

The effect of EGM2008-based normal, normal-orthometric and Helmert orthometric height systems on the Australian levelling network / M. Filmer in Journal of geodesy, vol 84 n° 8 (August 2010)  

Public [article]  inJournal of geodesy > vol 84 n° 8 (August 2010) . - pp 501 - 513 Titre : The effect of EGM2008-based normal, normal-orthometric and Helmert orthometric height systems on the Australian levelling network Type de document : Article/Communication Auteurs : M. Filmer, Auteur ; Will E. Featherstone, Auteur ; M. Kuhn, Auteur Année de publication : 2010 Article en page(s) : pp 501 - 513 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique [Termes IGN] altitude [Termes IGN] altitude orthométrique [Termes IGN] Australian Height Datum [Termes IGN] Australie [Termes IGN] correction orthométrique [Termes IGN] Earth Gravity Model 2008 [Termes IGN] réseau altimétrique national [Termes IGN] système de référence altimétrique Résumé : (Auteur) This paper investigates the normal-orthometric correction used in the definition of the Australian Height Datum, and also computes and evaluates normal and Helmert orthometric corrections for the Australian National Levelling Network (ANLN). Testing these corrections in Australia is important to establish which height system is most appropriate for any new Australian vertical datum. An approximate approach to assigning gravity values to ANLN benchmarks (BMs) is used, where the EGM2008-modelled gravity field is used to ‘re-construct’ observed gravity at the BMs. Network loop closures (for first- and second-order levelling) indicate reduced misclosures for all height corrections considered, particularly in the mountainous regions of south eastern Australia. Differences between Helmert orthometric and normal-orthometric heights reach 44 cm in the Australian Alps, and differences between Helmert orthometric and normal heights are about 26 cm in the same region. Normal-orthometric heights differ from normal heights by up to 18 cm in mountainous regions >2,000 m. This indicates that the quasigeoid is not compatible with normal-orthometric heights in Australia. Numéro de notice : A2010-441 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-010-0388-0 Date de publication en ligne : 11/06/2010 En ligne : https://doi.org/10.1007/s00190-010-0388-0 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=30634 [article]

Exemplaires(1)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
266-2010081	SL	Revue	Centre de documentation	Revues en salle	Disponible