Journal of geodesy . vol 87 n° 9Paru le : 01/09/2013 ISBN/ISSN/EAN : 0949-7714 |
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Code-barres | Cote | Support | Localisation | Section | Disponibilité |
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266-2013091 | SL | Revue | Centre de documentation | Revues en salle | Disponible |
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Ajouter le résultat dans votre panierA technique for routinely updating the ITU-R database using radio occultation electron density profiles / Claudio Brunini in Journal of geodesy, vol 87 n° 9 (September 2013)
[article]
Titre : A technique for routinely updating the ITU-R database using radio occultation electron density profiles Type de document : Article/Communication Auteurs : Claudio Brunini, Auteur ; Francisco Azpilicueta, Auteur ; Bruno Nava, Auteur Année de publication : 2013 Article en page(s) : pp 813 - 823 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement du signal
[Termes IGN] Formosat / COSMIC
[Termes IGN] International Reference Ionosphere
[Termes IGN] ionosphère
[Termes IGN] mise à jour de base de données
[Termes IGN] modèle ionosphérique
[Termes IGN] orbite basse
[Termes IGN] radiooccultation
[Termes IGN] teneur totale en électrons
[Termes IGN] trajectographie par GPSRésumé : (Auteur) Well credited and widely used ionospheric models, such as the International Reference Ionosphere or NeQuick, describe the variation of the electron density with height by means of a piecewise profile tied to the F2-peak parameters: the electron density, NmF2 , and the height, hmF2. Accurate values of these parameters are crucial for retrieving reliable electron density estimations from those models. When direct measurements of these parameters are not available, the models compute the parameters using the so-called ITU-R database, which was established in the early 1960s. This paper presents a technique aimed at routinely updating the ITU-R database using radio occultation electron density profiles derived from GPS measurements gathered from low Earth orbit satellites. Before being used, these radio occultation profiles are validated by fitting to them an electron density model. A re-weighted Least Squares algorithm is used for down-weighting unreliable measurements (occasionally, entire profiles) and to retrieve NmF2 and hmF2 values—together with their error estimates—from the profiles. These values are used to monthly update the database, which consists of two sets of ITU-R-like coefficients that could easily be implemented in the IRI or NeQuick models. The technique was tested with radio occultation electron density profiles that are delivered to the community by the COSMIC/FORMOSAT-3 mission team. Tests were performed for solstices and equinoxes seasons in high and low-solar activity conditions. The global mean error of the resulting maps—estimated by the Least Squares technique—is between 0.5*1010 and 3.6*1010 elec/m-3 for the F2-peak electron density (which is equivalent to 7 % of the value of the estimated parameter) and from 2.0 to 5.6 km for the height ( ~ 2 %). Numéro de notice : A2013-563 Affiliation des auteurs : non IGN Thématique : IMAGERIE/POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-013-0648-x Date de publication en ligne : 13/06/2013 En ligne : https://doi.org/10.1007/s00190-013-0648-x Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=32699
in Journal of geodesy > vol 87 n° 9 (September 2013) . - pp 813 - 823[article]Exemplaires(1)
Code-barres Cote Support Localisation Section Disponibilité 266-2013091 SL Revue Centre de documentation Revues en salle Disponible Improvement of GPS/acoustic seafloor positioning precision through controlling the ship’s track line / M. Sato in Journal of geodesy, vol 87 n° 9 (September 2013)
[article]
Titre : Improvement of GPS/acoustic seafloor positioning precision through controlling the ship’s track line Type de document : Article/Communication Auteurs : M. Sato, Auteur ; M. Fujita, Auteur ; Y. Matsumoto, Auteur ; et al., Auteur Année de publication : 2013 Article en page(s) : pp 825 - 842 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Navigation et positionnement
[Termes IGN] bathymétrie acoustique
[Termes IGN] cable
[Termes IGN] fond marin
[Termes IGN] GPS assisté pour la navigation (technologies)
[Termes IGN] Japon
[Termes IGN] lever bathymétrique
[Termes IGN] navigation maritime
[Termes IGN] navire
[Termes IGN] positionnement par GPS
[Termes IGN] précision du positionnement
[Termes IGN] sondeur acoustiqueRésumé : (Auteur) The precision of GPS/acoustic seafloor positioning was improved by introducing a hull-mounted onboard system in March 2008, which allows us to conduct acoustic ranging measurements with the vessel sailing along the pre-determined track lines, while the early system before 2008 could only adopt the uncontrollable drifting observation. The continuity of the positioning results due to the transition was first confirmed through the comparison between results from sailing and drifting observations conducted in parallel. Using the data acquired for about 3 years since 2008, the repeatability of the determined position for the sailing observation was evaluated to be about 2 cm in root mean squares in the horizontal component, significantly better than that for the early drifting observation. The improvement of positioning precision probably resulted from the improvement of geometric distribution of acoustic ranging data by controlling the track lines. It was also shown that the sailing observation allows to obtain reliable results with a smaller amount of data. Comparison between the results in different sea regions suggests that positioning precision is better in the region along the Nankai Trough than in the region along the Japan Trench, probably because of the complicated acoustic velocity structure of seawater often observed in the latter. Furthermore, the precision of height determination was also improved, which leads us to expect that vertical crustal movement will be detectable in the future through accumulation of data as well as further technology development. Numéro de notice : A2013-564 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-013-0649-9 Date de publication en ligne : 02/07/2013 En ligne : https://doi.org/10.1007/s00190-013-0649-9 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=32700
in Journal of geodesy > vol 87 n° 9 (September 2013) . - pp 825 - 842[article]Exemplaires(1)
Code-barres Cote Support Localisation Section Disponibilité 266-2013091 SL Revue Centre de documentation Revues en salle Disponible The static gravity field model DGM-1S from GRACE and GOCE data: computation, validation and an analysis of GOCE mission’s added value / Hassan Hashemi Farahani in Journal of geodesy, vol 87 n° 9 (September 2013)
[article]
Titre : The static gravity field model DGM-1S from GRACE and GOCE data: computation, validation and an analysis of GOCE mission’s added value Type de document : Article/Communication Auteurs : Hassan Hashemi Farahani, Auteur ; Pavel Ditmar, Auteur ; R. Klees, Auteur Année de publication : 2013 Article en page(s) : pp 843 - 867 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique
[Termes IGN] champ de pesanteur terrestre
[Termes IGN] données GOCE
[Termes IGN] données GRACE
[Termes IGN] gradiométrie
[Termes IGN] modèle de géopotentielRésumé : (Auteur) We present a global static model of the Earth’s gravity field entitled DGM-1S based on GRACE and GOCE data. The collection of used data sets includes nearly 7 years of GRACE KBR data and 10 months of GOCE gravity gradient data. The KBR data are transformed with a 3-point differentiation into quantities that are approximately inter-satellite accelerations. Gravity gradients are processed in the instrumental frame. Noise is handled with a frequency-dependent data weighting. DGM-1S is complete to spherical harmonic degree 250 with a Kaula regularization being applied above degree 179. Its performance is compared with a number of other satellite-only GRACE/GOCE models by confronting them with (i) an independent model of the oceanic mean dynamic topography, and (ii) independent KBR and gravity gradient data. The tests reveal a competitive quality for DGM-1S. Importantly, we study added value of GOCE data by comparing the performance of satellite-only GRACE/GOCE models with models produced without GOCE data: either ITG-Grace2010s or EGM2008 depending on which of the two performs better in a given region. The test executed based on independent gravity gradients quantifies this added value as 25–38 % in the continental areas poorly covered with terrestrial gravimetry data (Equatorial Africa, Himalayas, and South America), 7–17 % in those with a good coverage with these data (Australia, North America, and North Eurasia), and 14 % in the oceans. This added value is shown to be almost entirely related to coefficients below degree 200. It is shown that this gain must be entirely attributed to gravity gradients acquired by the mission. The test executed based on an independent model of the mean dynamic topography suggests that problems still seem to exist in satellite-only GRACE/GOCE models over the Pacific ocean, where noticeable deviations between these models and EGM2008 are detected, too. Numéro de notice : A2013-565 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-013-0650-3 Date de publication en ligne : 12/07/2013 En ligne : https://doi.org/10.1007/s00190-013-0650-3 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=32701
in Journal of geodesy > vol 87 n° 9 (September 2013) . - pp 843 - 867[article]Exemplaires(1)
Code-barres Cote Support Localisation Section Disponibilité 266-2013091 SL Revue Centre de documentation Revues en salle Disponible