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A strategy for determining the regional geoid by combining limited ground data with satellite-based global geopotential and topographical models: a case study of Iran / R. Kiamehr in Journal of geodesy, vol 79 n° 10-11 (February 2006)  

Public [article]  inJournal of geodesy > vol 79 n° 10-11 (February 2006) . - pp 602 - 612 Titre : A strategy for determining the regional geoid by combining limited ground data with satellite-based global geopotential and topographical models: a case study of Iran Type de document : Article/Communication Auteurs : R. Kiamehr, Auteur Année de publication : 2006 Article en page(s) : pp 602 - 612 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique [Termes IGN] anomalie de pesanteur [Termes IGN] données hétérogènes [Termes IGN] formule de Stokes [Termes IGN] géoïde gravimétrique [Termes IGN] géoïde local [Termes IGN] Iran [Termes IGN] méthode des moindres carrés [Termes IGN] MNS SRTM [Termes IGN] modèle numérique de terrain [Termes IGN] nivellement par GPS Résumé : (Auteur) The computation of regional gravimetric geoid models with reasonable accuracy, in developing countries, with sparse data is a difficult task that needs great care. Here, we investigate the procedure for gathering, evaluating and combining different data for the determination of a gravimetric geoid model for Iran, where limited ground gravity data are available. Heterogeneous data, including gravity anomalies, the high-resolution Shuttle Radar Topography Mission global digital terrain model and different global geopotential models including recently published Gravity Recovery and Climate Experiment models, are combined through least-squares modification of the Stokes formula. The new gravimetric geoid model, IRG04, agrees considerably better with GPS-levelling than any of the other recent local geoid model in the area. Its RMS fit with GPS-levelling is 0.27m and 3.8 ppm in the absolute and relative view, respectively. The relative accuracy of IRG04 is four times better than the most recently published global and regional geoid models available in this area. This progress shows the practical potential of the method of least-squares modification of Stokes's formula in combination with heterogeneous data for regional geoid determination. Numéro de notice : A2006-087 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-005-0009-5 En ligne : https://doi.org/10.1007/s00190-005-0009-5 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=27814 [article]

Exemplaires(2)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
266-06012	RAB	Revue	Centre de documentation	En réserve L003	Disponible
266-06011	RAB	Revue	Centre de documentation	En réserve L003	Disponible

Effect of the STRM global DEM on the determination of a high-resolution geoid model: A case study in Iran / R. Kiamehr in Journal of geodesy, vol 79 n° 9 (December 2005)  

Public [article]  inJournal of geodesy > vol 79 n° 9 (December 2005) . - pp 540 - 551 Titre : Effect of the STRM global DEM on the determination of a high-resolution geoid model: A case study in Iran Type de document : Article/Communication Auteurs : R. Kiamehr, Auteur ; Lard Erik Sjöberg, Auteur Année de publication : 2005 Article en page(s) : pp 540 - 551 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique [Termes IGN] altitude [Termes IGN] anomalie de pesanteur [Termes IGN] géoïde gravimétrique [Termes IGN] géoïde local [Termes IGN] Iran [Termes IGN] MNS SRTM [Termes IGN] modèle numérique de surface [Termes IGN] modèle numérique de terrain [Termes IGN] nivellement [Termes IGN] positionnement par GPS [Termes IGN] propagation d'erreur Résumé : (Auteur) Any errors in digital elevation models (DEMs) will introduce errors directly in gravity anomalies and geoid models when used in interpolating Bouguer gravity anomalies. Errors are also propagated into the geoid model by the topographie and downward continuation (DWC) corrections in the application of Stokes's formula. The effects of those errors are assessed by the evaluation of the absolute accuracy of nine independent DEMs for the Iran region. It is shown that the improvement in using the high-resolution Shuttle Radar Topography Mission (SRTM) data versus previously available DEMs in gridding of gravity anomalies, terrain corrections and DWC effects for the geoid model are significant. Based on the Iranian GPS/levelling network data, we estimate the absolute vertical accuracy of the SRTM in Iran to be 6.5 m, which is much better than the estimated global accuracy of the SRTM (say 16 m). Hence, this DEM has a comparable accuracy to a current photogrammetric high-resolution DEM of Iran under development. We also found very large differences between the GLOBE and SRTM models on the range of -750 to 550 m. This difference causes an error in the range of -160 to 140mGal in interpolating surface gravity anomalies and -60 to 60 mGal in simple Bouguer anomaly correction terins. In the view of geoid heights, we found large differences between the use of GLOBE and SRTM DEMs, in the range of - 1.1 to 1 m for the study area. The terrain correction of the geoid model at selected GPS/levelling points only differs by 3 cm for these two DEMs. Numéro de notice : A2005-609 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-005-0006-8 En ligne : https://doi.org/10.1007/s00190-005-0006-8 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=27656 [article]

Exemplaires(2)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
266-05091	RAB	Revue	Centre de documentation	En réserve L003	Disponible
266-05092	RAB	Revue	Centre de documentation	En réserve L003	Disponible