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Joint analysis of GOCE gravity gradients data of gravitational potential and of gravity with seismological and geodynamic observations to infer mantle properties / Marianne Greff-Lefftz in Geophysical journal international, vol 205 n° 1 (April 2016)
[article]
Titre : Joint analysis of GOCE gravity gradients data of gravitational potential and of gravity with seismological and geodynamic observations to infer mantle properties Type de document : Article/Communication Auteurs : Marianne Greff-Lefftz, Auteur ; Laurent Métivier , Auteur ; Isabelle Panet , Auteur ; Lambert Caron, Auteur ; Gwendoline Pajot-Métivier , Auteur ; Johannes Bouman, Auteur Année de publication : 2016 Projets : TOSCA / Article en page(s) : pp 257 - 283 Note générale : bibliographie
This study was supported by CNES (Centre National d’Etudes Spatiales) through the TOSCA committee and is IPGP contribution number 3701.Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale
[Termes IGN] champ de pesanteur terrestre
[Termes IGN] données GOCE
[Termes IGN] facteur d'échelle
[Termes IGN] gradient de gravitation
[Termes IGN] manteau terrestre
[Termes IGN] méthode de Monte-Carlo
[Termes IGN] potentiel de pesanteur terrestre
[Termes IGN] viscositéRésumé : (auteur) Joint analysis of the seismic velocities and geoid, gravity and gravity gradients are used to constrain the viscosity profile within the mantle as well as the lateral density variations. Recent ESA's Gravity field and steady-state Ocean Circulation Explorer measurements of the second-order derivatives of the Earth's gravity potential give new possibilities to determine these mantle properties. Using a simple mantle model and seismic tomography results, we investigate how the gravitational potential, the three components of the gravity vector and the gravity gradients can bring information on the radial viscosity profile and on the mantle mass anomalies. We start with lateral density variations in the Earth's mantle based either on slab history or deduced from seismic tomography. The main uncertainties are: for the latter case, the relationship between seismic velocity and density—the so-called density/velocity scaling factor—and for the former case, the variation with depth of the density contrast between the cold slabs and the surrounding mantle. We perform a Monte Carlo search for the viscosity and the density/velocity scaling factor profiles within the mantle, which allows to fit the observed geoid, gravity and gradients of gravity. We compute the posterior probability distribution of the unknown parameters, and find that the gravity gradients improve the estimate of the scaling factor within the upper mantle, because of their sensitivity to the masses within the upper mantle, whereas the geoid and the gravity better constrain the scaling factor in the lower mantle. In the upper mantle, it is less than 0.02 in the upper part and about 0.08–0.14 in the lower part, and it is significantly larger for depths greater than 1200 km (about 0.32–0.34). In any case, the density/velocity scaling factor between 670 and 1150 km depth is not well constrained. We show that the viscosity of the upper part of the mantle is strongly correlated with the viscosity of the lower part of the mantle and that the viscosity profile is characterized by a decrease in the lower part of the upper mantle (about 1020–2 × 1020 Pa s) and by an increase (about 1023–2 × 1023 Pa s) at the top of the lower mantle (between 670 and 1150 km). The viscosity of the mantle below 1150 km depth is well estimated in our Monte Carlo search and is about 1022–4 × 1022 Pa s. Numéro de notice : A2016--192 Affiliation des auteurs : LASTIG LAREG+Ext (2012-mi2018) Autre URL associée : vers HAL Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1093/gji/ggw002 Date de publication en ligne : 16/02/2016 En ligne : https://doi.org/10.1093/gji/ggw002 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=91843
in Geophysical journal international > vol 205 n° 1 (April 2016) . - pp 257 - 283[article]Performance analysis of triple-frequency ambiguity resolution with BeiDou observations / Xiaohong Zhang in GPS solutions, vol 20 n° 2 (April 2016)
[article]
Titre : Performance analysis of triple-frequency ambiguity resolution with BeiDou observations Type de document : Article/Communication Auteurs : Xiaohong Zhang, Auteur ; Xiyang He, Auteur Année de publication : 2016 Article en page(s) : pp 269 - 281 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale
[Termes IGN] compensation Lambda
[Termes IGN] correction du trajet multiple
[Termes IGN] données BeiDou
[Termes IGN] performance
[Termes IGN] récepteur trifréquence
[Termes IGN] résolution d'ambiguïtéRésumé : (Auteur) We investigate triple-frequency ambiguity resolution performance using real BeiDou data. We test four ambiguity resolution (AR) methods which are applicable to triple-frequency observations. These are least squares ambiguity decorrelation adjustment (LAMBDA), GF-TCAR (geometry-free three-carrier ambiguity resolution), GB-TCAR (geometry-based three-carrier ambiguity resolution) and GIF-TCAR (three-carrier ambiguity resolution based on the geometry-free and ionospheric-free combination). A comparison between LAMBDA, GF-TCAR and GB-TCAR was conducted over three short baselines and two medium baselines. The results indicated that LAMBDA is optimal in both short baseline and medium baseline cases. However, the performances of GB-TCAR and LAMBDA differ slightly for short baselines. Compared with GF-TCAR, which uses the geometry-free model, the GB-TCAR using the geometry-based model improves the AR performance significantly. Compared with dual-frequency observations, the LAMBDA AR results show a significant improvement when using triple-frequency observations over short baselines. The performance of GIF-TCAR is evaluated using multi-epoch observations. The results indicated that multi-path errors on carrier phases will have a significant influence on GIF-TCAR AR results, which leads to different GIF-TCAR AR performance for different type of satellites. For GEO (Geostationary Orbit) satellites, the ambiguities can barely be correctly fixed because the multi-path errors on carrier phases are very systematic. For IGSO (Inclined Geosynchronous Orbit) and MEO (Medium Earth Orbit) satellites, when the elevation cutoff angle is set as 30°, several tens to several hundreds of epochs are needed for correctly fixing the narrow lane ambiguities. The comparison of positioning performance between dual-frequency observations and triple-frequency observations was also conducted. The results indicated that a minor improvement can be achieved by using triple-frequency observations compared with using dual-frequency observations. Numéro de notice : A2016-614 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.1007/s10291-014-0434-0 En ligne : http://dx.doi.org/10.1007/s10291-014-0434-0 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=81814
in GPS solutions > vol 20 n° 2 (April 2016) . - pp 269 - 281[article]A study on the dependency of GNSS pseudorange biases on correlator spacing / André Hauschild in GPS solutions, vol 20 n° 2 (April 2016)
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Titre : A study on the dependency of GNSS pseudorange biases on correlator spacing Type de document : Article/Communication Auteurs : André Hauschild, Auteur ; Oliver Montenbruck, Auteur Année de publication : 2016 Article en page(s) : pp 159 - 171 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Termes IGN] correction du trajet multiple
[Termes IGN] corrélation
[Termes IGN] erreur systématique
[Termes IGN] mesurage de pseudo-distance
[Termes IGN] mitigation
[Termes IGN] puce
[Termes IGN] récepteur GNSS
[Termes IGN] signal GNSS
[Vedettes matières IGN] Traitement de données GNSSRésumé : (Auteur) We provide a comprehensive overview of pseudorange biases and their dependency on receiver front-end bandwidth and correlator design. Differences in the chip shape distortions among GNSS satellites are the cause of individual pseudorange biases. The different biases must be corrected for in a number of applications, such as positioning with mixed signals or PPP with ambiguity resolution. Current state-of-the-art is to split the pseudorange bias into a receiver- and a satellite-dependent part. As soon as different receivers with different front-end bandwidths or correlator designs are involved, the satellite biases differ between the receivers and this separation is no longer practicable. A test with a special receiver firmware, which allows tracking a satellite with a range of different correlator spacings, has been conducted with live signals as well as a signal simulator. In addition, the variability of satellite biases is assessed through zero-baseline tests with different GNSS receivers using live satellite signals. The receivers are operated with different settings for multipath mitigation, and the changes in the satellite-dependent biases depending on the receivers’ configuration are observed. Numéro de notice : A2016-610 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.1007/s10291-014-0426-0 En ligne : http://dx.doi.org/10.1007/s10291-014-0426-0 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=81807
in GPS solutions > vol 20 n° 2 (April 2016) . - pp 159 - 171[article]An average error-ellipsoid model for evaluating TLS point-cloud accuracy / Xijiang Chen in Photogrammetric record, vol 31 n° 153 (March - May 2016)
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Titre : An average error-ellipsoid model for evaluating TLS point-cloud accuracy Type de document : Article/Communication Auteurs : Xijiang Chen, Auteur ; Guang Zhang, Auteur ; Xianghong Hua, Auteur ; Wei Xuan, Auteur Année de publication : 2016 Article en page(s) : pp 71 - 87 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Lasergrammétrie
[Termes IGN] données lidar
[Termes IGN] données localisées 3D
[Termes IGN] erreur moyenne
[Termes IGN] estimation statistique
[Termes IGN] précision des données
[Termes IGN] qualité des données
[Termes IGN] semis de points
[Termes IGN] télémétrie laser terrestreRésumé : (Auteur) Estimation of the accuracy of terrestrial laser scanning has become a topical research issue. Point-cloud accuracy should be clearly differentiated from the accuracy of individual points, as it is influenced by positional errors and adjacent error spaces. Furthermore, it cannot be determined by the sum of positional errors. In this paper, it is proposed that the average error-ellipsoid model is favourable for evaluating the accuracy of point clouds. Central to this model is the computation of the overlap between adjacent error ellipsoids and the determination of a functional relationship between the average volume of error ellipsoids and the point-cloud accuracy. This paper outlines the key advantages of the proposed evaluation model, such as the capability of providing an estimate of local point-cloud accuracy. The effectiveness of the model is discussed using a validation experiment. Numéro de notice : A2016-162 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article DOI : 10.1111/phor.12136 Date de publication en ligne : 02/03/2016 En ligne : https://doi.org/10.1111/phor.12136 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=80462
in Photogrammetric record > vol 31 n° 153 (March - May 2016) . - pp 71 - 87[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 106-2016011 RAB Revue Centre de documentation En réserve L003 Disponible Approximating prediction uncertainty for random forest regression models / John W. Coulston in Photogrammetric Engineering & Remote Sensing, PERS, vol 82 n° 3 (March 2016)
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Titre : Approximating prediction uncertainty for random forest regression models Type de document : Article/Communication Auteurs : John W. Coulston, Auteur ; Christine E. Blinn, Auteur ; Valerie A. Thomas, Auteur ; Randolph H. Wynne, Auteur Année de publication : 2016 Article en page(s) : pp 189 - 197 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de télédétection
[Termes IGN] classification par forêts d'arbres décisionnels
[Termes IGN] incertitude des données
[Termes IGN] méthode de Monte-Carlo
[Termes IGN] modèle de régression
[Termes IGN] prédiction
[Termes IGN] variableRésumé : (auteur) Machine learning approaches such as random forest have increased for the spatial modeling and mapping of continuous variables. Random forest is a non-parametric ensemble approach, and unlike traditional regression approaches there is no direct quantification of prediction error. Understanding prediction uncertainty is important when using model-based continuous maps as inputs to other modeling applications such as fire modeling. Here we use a Monte Carlo approach to quantify prediction uncertainty for random forest regression models. We test the approach by simulating maps of dependent and independent variables with known characteristics and comparing actual errors with prediction errors. Our approach produced conservative prediction intervals across most of the range of predicted values. However, because the Monte Carlo approach was data driven, prediction intervals were either too wide or too narrow in sparse parts of the prediction distribution. Overall, our approach provides reasonable estimates of prediction uncertainty for random forest regression models. Numéro de notice : A2016-176 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article DOI : 10.14358/PERS.82.3.189 En ligne : https://doi.org/10.14358/PERS.82.3.189 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=80506
in Photogrammetric Engineering & Remote Sensing, PERS > vol 82 n° 3 (March 2016) . - pp 189 - 197[article]Challenges and present fields of action at laser scanner based deformation analyses / Christoph Holst in Journal of applied geodesy, vol 10 n° 1 (March 2016)PermalinkDetermination of differential code biases with multi-GNSS observations / Ningbo Wang in Journal of geodesy, vol 90 n° 3 (March 2016)PermalinkMarkov random field-based method for super-resolution mapping of forest encroachment from remotely sensed ASTER image / L. K. Tiwari in Geocarto international, vol 31 n° 3 - 4 (March - April 2016)PermalinkMIDAS robust trend estimator for accurate GPS station velocities without step detection / Geoffrey Blewitt in Journal of geophysical research : Solid Earth, vol 121 n° 3 (March 2016)PermalinkNoise simulation and correction in synthetic airborne TIR Data for mineral quantification / Christoph Hecker in IEEE Transactions on geoscience and remote sensing, vol 54 n° 3 (March 2016)PermalinkReal time monitoring ground motion using GPS with real time corrections / R. Tu in Survey review, vol 48 n° 347 (March 2016)PermalinkRobust spatial approximation of laser scanner point clouds by means of Free-form Curve approaches in deformation analysis / Johannes Bureick in Journal of applied geodesy, vol 10 n° 1 (March 2016)PermalinkThe reliability of RANSAC method when estimating the parameters of geometric object / Tilen Urbančič in Geodetski vestnik, vol 60 n° 1 (March - May 2016)PermalinkA correctly weighted least squares adjustment - Part 2 Estimating uncertainties / Charles D. Ghilani in xyHt, vol 2016 n° 2 (February 2016)PermalinkLa géostatistique : une vision novatrice au service des géosciences / Bernard Bourgine in Géosciences, n°20 (février 2016)Permalink