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Geodetic monitoring of subrosion-induced subsidence processes in urban areas / Tobias Kersten in Journal of applied geodesy, vol 11 n° 1 (March 2017)
[article]
Titre : Geodetic monitoring of subrosion-induced subsidence processes in urban areas Type de document : Article/Communication Auteurs : Tobias Kersten, Auteur ; Martin Kobe, Auteur ; Gerald Gabriel, Auteur ; Ludger Timmen, Auteur ; Steffen Schön, Auteur ; Detlef Vogel, Auteur Année de publication : 2017 Article en page(s) : pp 21 - 30 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale
[Termes IGN] église
[Termes IGN] gravimétrie
[Termes IGN] Hambourg
[Termes IGN] nivellement
[Termes IGN] positionnement par GNSS
[Termes IGN] réseau de surveillance géophysique
[Termes IGN] subsidence
[Termes IGN] surveillance géologique
[Termes IGN] Thuringe
[Termes IGN] tour (bâtiment)
[Termes IGN] zone urbaineRésumé : (Résumé) The research project SIMULTAN applies an advanced combination of geophysical, geodetic, and modelling techniques to gain a better understanding of the evolution and characteristics of sinkholes. Sinkholes are inherently related to surface deformation and, thus, of increasing societal relevance, especially in dense populated urban areas. One work package of SIMULTAN investigates an integrated approach to monitor sinkhole-related mass translations and surface deformations induced by salt dissolution. Datasets from identical and adjacent points are used for a consistent combination of geodetic and geophysical techniques. Monitoring networks are established in Hamburg and Bad Frankenhausen (Thuringia). Levelling surveys indicate subsidence rates of about 4–5 mm per year in the main subsidence areas of Bad Frankenhausen with a local maximum of 10 mm per year around the leaning church tower.
Here, the concept of combining geodetic and gravimetric techniques to monitor and characterise geological processes on and below the Earth's surface is exemplary discussed for the focus area Bad Frankenhausen. For the different methods (levelling, GNSS, relative/absolute gravimetry) stable network results at identical points are obtained by the first campaigns, i.e., the results are generally in agreement.Numéro de notice : A2017-281 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.1515/jag-2016-0029 En ligne : https://doi.org/10.1515/jag-2016-0029 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=85314
in Journal of applied geodesy > vol 11 n° 1 (March 2017) . - pp 21 - 30[article]
[article]
Titre : Géoïde : mythe ou réalité ? Type de document : Article/Communication Auteurs : Françoise Duquenne , Auteur ; François L'écu, Auteur ; Julien Gazeaux , Auteur Année de publication : 2017 Article en page(s) : pp 39 - 48 Note générale : Bibliographie Langues : Français (fre) Descripteur : [Vedettes matières IGN] Géodésie physique
[Termes IGN] altitude normale
[Termes IGN] altitude orthométrique
[Termes IGN] conversion altimétrique
[Termes IGN] géoïde
[Termes IGN] gravimétrie spatiale
[Termes IGN] mission spatiale
[Termes IGN] précision centimétrique
[Termes IGN] quasi-géoïde
[Termes IGN] récepteur GNSS
[Termes IGN] transformation de coordonnéesRésumé : (Auteur) Il devient dorénavant possible de déterminer la hauteur de n'importe quel sommet montagneux avec une précision centimétrique. Il suffit pour cela d'y monter avec un récepteur GNSS multifréquence, de respecter les temps d'observations et d'utiliser les méthodes de calculs précis. On peut alors atteindre ce centimètre tant désiré dans la détermination de la hauteur au-dessus d'un ellipsoïde et dans un référentiel géodésique bien précis. Pourtant dans les colonnes de la plupart des journaux (on remarquera ici que XYZ, ne fait pas partie du lot) on lit souvent que l'altitude a été mesurée au centimètre près. Le passage de la hauteur au-dessus de l'ellipsoïde à l'altitude n'a rien de trivial et le centimètre est difficile à obtenir dans cette transformation, même si comme on l'entend souvent il suffit d'utiliser un géoïde. Le but des lignes ci-dessous est, tout en reprenant les notions de base, de faire le point sur ce qu'on peut attendre en matière de géoïde et de conversion de hauteur en altitude. Numéro de notice : A2017-094 Affiliation des auteurs : IGN+Ext (2012-2019) Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueNat DOI : sans Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=84432
in XYZ > n° 150 (mars - mai 2017) . - pp 39 - 48[article]Réservation
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Géoïde : mythe ou réalité ? - pdf éditeurAdobe Acrobat PDF Assessment of second- and third-order ionospheric effects on regional networks : case study in China with longer CMONOC GPS coordinate time series / Liansheng Deng in Journal of geodesy, vol 91 n° 2 (February 2017)
[article]
Titre : Assessment of second- and third-order ionospheric effects on regional networks : case study in China with longer CMONOC GPS coordinate time series Type de document : Article/Communication Auteurs : Liansheng Deng, Auteur ; Weiping Jiang, Auteur ; Zhao Li, Auteur ; et al., Auteur Année de publication : 2017 Article en page(s) : pp 207 - 227 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Systèmes de référence et réseaux
[Termes IGN] analyse diachronique
[Termes IGN] Chine
[Termes IGN] coordonnées GPS
[Termes IGN] correction ionosphérique
[Termes IGN] déformation de la croute terrestre
[Termes IGN] effet atmosphérique
[Termes IGN] propagation ionosphérique
[Termes IGN] réseau géodésique local
[Termes IGN] retard ionosphèrique
[Termes IGN] série temporelle
[Termes IGN] surcharge atmosphériqueRésumé : (Auteur) Higher-order ionospheric (HOI) delays are one of the principal technique-specific error sources in precise global positioning system analysis and have been proposed to become a standard part of precise GPS data processing. In this research, we apply HOI delay corrections to the Crustal Movement Observation Network of China’s (CMONOC) data processing (from January 2000 to December 2013) and furnish quantitative results for the effects of HOI on CMONOC coordinate time series. The results for both a regional reference frame and global reference frame are analyzed and compared to clarify the HOI effects on the CMONOC network. We find that HOI corrections can effectively reduce the semi-annual signals in the northern and vertical components. For sites with lower semi-annual amplitudes, the average decrease in magnitude can reach 30 and 10 % for the northern and vertical components, respectively. The noise amplitudes with HOI corrections and those without HOI corrections are not significantly different. Generally, the HOI effects on CMONOC networks in a global reference frame are less obvious than the results in the regional reference frame, probably because the HOI-induced errors are smaller in comparison to the higher noise levels seen when using a global reference frame. Furthermore, we investigate the combined contributions of environmental loading and HOI effects on the CMONOC stations. The largest loading effects on the vertical displacement are found in the mid- to high-latitude areas. The weighted root mean square differences between the corrected and original weekly GPS height time series of the loading model indicate that the mass loading adequately reduced the scatter on the CMONOC height time series, whereas the results in the global reference frame showed better agreements between the GPS coordinate time series and the environmental loading. When combining the effects of environmental loading and HOI corrections, the results with the HOI corrections reduced the scatter on the observed GPS height coordinates better than the height when estimated without HOI corrections, and the combined solutions in the regional reference frame indicate more preferred improvements. Therefore, regional reference frames are recommended to investigate the HOI effects on regional networks. Numéro de notice : A2017-064 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-016-0957-y En ligne : http://dx.doi.org/10.1007/s00190-016-0957-y Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=84278
in Journal of geodesy > vol 91 n° 2 (February 2017) . - pp 207 - 227[article]Geodesic equations and their numerical solutions in geodetic and cartesian coordinates on an oblate spheroid / Georgios Panou in Journal of geodetic science, vol 7 n° 1 (February 2017)
[article]
Titre : Geodesic equations and their numerical solutions in geodetic and cartesian coordinates on an oblate spheroid Type de document : Article/Communication Auteurs : Georgios Panou, Auteur ; Romylos Korakitis, Auteur Année de publication : 2017 Article en page(s) : pp 31 - 42 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Systèmes de référence et réseaux
[Termes IGN] coordonnées cartésiennes
[Termes IGN] coordonnées géodésiques
[Termes IGN] géométrie différentielle
[Termes IGN] problème des valeurs limites
[Termes IGN] sphèroïde
[Termes IGN] système de coordonnéesRésumé : (Auteur) The direct geodesic problem on an oblate spheroid is described as an initial value problem and is solved numerically using both geodetic and Cartesian coordinates. The geodesic equations are formulated by means of the theory of differential geometry. The initial value problem under consideration is reduced to a system of first-order ordinary differential equations, which is solved using a numerical method. The solution provides the coordinates and the azimuths at any point along the geodesic. The Clairaut constant is not used for the solution but it is computed, allowing to check the precision of the method. An extensive data set of geodesics is used, in order to evaluate the performance of the method in each coordinate system. The results for the direct geodesic problem are validated by comparison to Karney’s method. We conclude that a complete, stable, precise, accurate and fast solution of the problem in Cartesian coordinates is accomplished. Numéro de notice : A2017-300 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.1515/jogs-2017-0004 En ligne : https://doi.org/10.1515/jogs-2017-0004 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=85335
in Journal of geodetic science > vol 7 n° 1 (February 2017) . - pp 31 - 42[article]GRACE era variability in the Earth's oblateness: a comparison of estimates from six different sources / Thierry Meyrath in Geophysical journal international, vol 208 n° 2 (February 2017)
[article]
Titre : GRACE era variability in the Earth's oblateness: a comparison of estimates from six different sources Type de document : Article/Communication Auteurs : Thierry Meyrath, Auteur ; Paul Rebischung , Auteur ; Tonie M. van Dam, Auteur Année de publication : 2017 Projets : 1-Pas de projet / Article en page(s) : pp 1126 - 1138 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique
[Termes IGN] données GRACE
[Termes IGN] données TLS (télémétrie)
[Termes IGN] gravimétrie spatiale
[Termes IGN] longueur du jour
[Termes IGN] potentiel de pesanteur terrestre
[Termes IGN] rotation de la Terre
[Termes IGN] série temporelleRésumé : (auteur) We study fluctuations in the degree-2 zonal spherical harmonic coefficient of the Earth's gravity potential, C20, over the period 2003–2015. This coefficient is related to the Earth's oblateness and studying its temporal variations, ΔC20, can be used to monitor large-scale mass movements between high and low latitude regions. We examine ΔC20 inferred from six different sources, including satellite laser ranging (SLR), GRACE and global geophysical fluids models. We further include estimates that we derive from measured variations in the length-of-day (LOD), from the inversion of global crustal displacements as measured by GPS, as well as from the combination of GRACE and the output of an ocean model as described by Sun et al. We apply a sequence of trend and seasonal moving average filters to the different time-series in order to decompose them into an interannual, a seasonal and an intraseasonal component. We then perform a comparison analysis for each component, and we further estimate the noise level contained in the different series using an extended version of the three-cornered-hat method. For the seasonal component, we generally obtain a very good agreement between the different sources, and except for the LOD-derived series, we find that over 90 per cent of the variance in the seasonal components can be explained by the sum of an annual and semiannual oscillation of constant amplitudes and phases, indicating that the seasonal pattern is stable over the considered time period. High consistency between the different estimates is also observed for the intraseasonal component, except for the solution from GRACE, which is known to be affected by a strong tide-like alias with a period of about 161 d. Estimated interannual components from the different sources are generally in agreement with each other, although estimates from GRACE and LOD present some discrepancies. Slight deviations are further observed for the estimate from the geophysical models, likely to be related to the omission of polar ice and groundwater changes in the model combination we use. On the other hand, these processes do not seem to play an important role at seasonal and shorter timescales, as the sum of modelled atmospheric, oceanic and hydrological effects effectively explains the observed C20 variations at those scales. We generally obtain very good results for the solution from SLR, and we confirm that this well-established technique accurately tracks changes in C20. Good agreement is further observed for the estimate from the GPS inversion, showing that this indirect method is successful in capturing fluctuations in C20 on scales ranging from intra- to interannual. Obtaining accurate estimates from LOD, however, remains a challenging task and more reliable models of atmospheric wind fields are needed in order to obtain high-quality ΔC20, in particular at the seasonal scale. The combination of GRACE data and the output of an ocean model appears to be a promising approach, particularly since corresponding ΔC20 is not affected by tide-like aliases, and generally gives better results than the solution from GRACE, which still seems to be of rather poor quality. Numéro de notice : A2017-863 Affiliation des auteurs : LASTIG LAREG+Ext (2012-mi2018) Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1093/gji/ggw441 Date de publication en ligne : 24/11/2016 En ligne : https://doi.org/10.1093/gji/ggw441 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=89852
in Geophysical journal international > vol 208 n° 2 (February 2017) . - pp 1126 - 1138[article]On the consistency of the current conventional EOP series and the celestial and terrestrial reference frames / Santiago Belda in Journal of geodesy, vol 91 n° 2 (February 2017)PermalinkPermalinkEléments de géodésie et de la théorie des moindres carrés / Abdelmajid Ben Hadj Salem (2017)PermalinkLa gravimétrie mobile en champ proche : outil essentiel pour la haute résolution en géodésie physique et en géosciences / Jérome Verdun (2017)PermalinkPermalinkLes références de temps et d'espace / Claude Boucher (2017)PermalinkIs the Jason-2 DORIS oscillator also affected by the South Atlantic Anomaly? / Pascal Willis in Advances in space research, vol 58 n° 12 (15 December 2016)PermalinkThe International DORIS Service contribution to the 2014 realization of the International Terrestrial Reference Frame / Guilhem Moreaux in Advances in space research, vol 58 n° 12 (15 December 2016)PermalinkAssessment of the accuracy of global geodetic satellite laser ranging observations and estimated impact on ITRF scale: estimation of systematic errors in LAGEOS observations 1993–2014 / Graham Appleby in Journal of geodesy, vol 90 n° 12 (December 2016)PermalinkComplex demodulation in monitoring earth rotation by VLBI: testing the algorithm by analysis of long periodic EOP components / Agata Wielgosz in Artificial satellites, vol 51 n° 4 (December 2016)Permalink