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Modélisation des retards troposphériques pour les observations GPS et impacts sur l'estimation de la hauteur ellipsoïdale / François Fund in XYZ, n° 123 (juin - août 2010)
[article]
Titre : Modélisation des retards troposphériques pour les observations GPS et impacts sur l'estimation de la hauteur ellipsoïdale Type de document : Article/Communication Auteurs : François Fund, Auteur ; Laurent Morel, Auteur ; A. Mocquet, Auteur Année de publication : 2010 Article en page(s) : pp 27 - 32 Note générale : Bibliographie Langues : Français (fre) Descripteur : [Vedettes matières IGN] Géodésie spatiale
[Termes IGN] données GPS
[Termes IGN] données météorologiques
[Termes IGN] hauteur ellipsoïdale
[Termes IGN] humidité de l'air
[Termes IGN] modèle atmosphérique
[Termes IGN] propagation troposphériqueRésumé : (Auteur) L'estimation d'une hauteur ellipsoïdale par GPS est connue pour être d'une précision inférieure à celles des composantes planimétriques. En première approximation, on peut l'expliquer par la couverture des satellites qui ne décrit pas complètement la géométrie du problème. Pourtant, d'autres paramètres peuvent aisément dégrader l'estimation de la hauteur. Un paramètre majeur concerne la traversée de la troposphère qui affecte radialement les observations GPS. Certes dans un contexte de positionnement différentiel à base courte de quelques kilomètres, cette problématique est largement résolue. Cependant pour le traitement précis de réseaux GPS à longues lignes de base, elle ne peut plus être négligée. Le choix de la modélisation des effets troposphériques peut alors entraîner des variations de plusieurs millimètres sur les estimations des hauteurs des stations du réseau. Les recherches menées parla communauté internationale depuis quelques décennies ont permis d'aboutir à différentes solutions de hauteur dont la précision ne cesse de s'améliorer. Numéro de notice : A2010-214 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : sans Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=30408
in XYZ > n° 123 (juin - août 2010) . - pp 27 - 32[article]Exemplaires(1)
Code-barres Cote Support Localisation Section Disponibilité 112-2010021 RAB Revue Centre de documentation En réserve L003 Exclu du prêt Upper mantle rheology from GRACE and GPS postseismic deformation after the 2004 Sumatra‐Andaman earthquake / Isabelle Panet in Geochemistry, Geophysics, Geosystems, vol 11 n° 6 (June 2010)
[article]
Titre : Upper mantle rheology from GRACE and GPS postseismic deformation after the 2004 Sumatra‐Andaman earthquake Type de document : Article/Communication Auteurs : Isabelle Panet , Auteur ; Fred Pollitz, Auteur ; Valentin O. Mikhailov, Auteur ; Michel Diament , Auteur ; P. Banerjee, Auteur ; K. Grijalva, Auteur Année de publication : 2010 Article en page(s) : 20 p. Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale
[Termes IGN] déformation de la croute terrestre
[Termes IGN] données GPS
[Termes IGN] données GRACE
[Termes IGN] manteau terrestre
[Termes IGN] rhéologie
[Termes IGN] séisme
[Termes IGN] SumatraRésumé : (auteur) Mantle rheology is one of the essential, yet least understood, material properties of our planet, controlling the dynamic processes inside the Earth's mantle and the Earth's response to various forces. With the advent of GRACE satellite gravity, measurements of mass displacements associated with many processes are now available. In the case of mass displacements related to postseismic deformation, these data may provide new constraints on the mantle rheology. We consider the postseismic deformation due to the Mw = 9.2 Sumatra 26 December 2004 and Mw = 8.7 Nias 28 March 2005 earthquakes. Applying wavelet analyses to enhance those local signals in the GRACE time varying geoids up to September 2007, we detect a clear postseismic gravity signal. We supplement these gravity variations with GPS measurements of postseismic crustal displacements to constrain postseismic relaxation processes throughout the upper mantle. The observed GPS displacements and gravity variations are well explained by a model of viscoelastic relaxation plus a small amount of afterslip at the downdip extension of the coseismically ruptured fault planes. Our model uses a 60 km thick elastic layer above a viscoelastic asthenosphere with Burgers body rheology. The mantle below depth 220 km has a Maxwell rheology. Assuming a low transient viscosity in the 60–220 km depth range, the GRACE data are best explained by a constant steady state viscosity throughout the ductile portion of the upper mantle (e.g., 60–660 km). This suggests that the localization of relatively low viscosity in the asthenosphere is chiefly in the transient viscosity rather than the steady state viscosity. We find a 8.1018 Pa s mantle viscosity in the 220–660 km depth range. This may indicate a transient response of the upper mantle to the high amount of stress released by the earthquakes. To fit the remaining misfit to the GRACE data, larger at the smaller spatial scales, cumulative afterslip of about 75 cm at depth should be added over the period spanned by the GRACE models. It produces only small crustal displacements. Our results confirm that satellite gravity data are an essential complement to ground geodetic and geophysical networks in order to understand the seismic cycle and the Earth's inner structure. Numéro de notice : A2010-655 Affiliation des auteurs : LAREG+Ext (1991-2011) Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1029/2009GC002905 Date de publication en ligne : 19/06/2010 En ligne : https://doi.org/10.1029/2009GC002905 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=91728
in Geochemistry, Geophysics, Geosystems > vol 11 n° 6 (June 2010) . - 20 p.[article]Documents numériques
en open access
Upper mantle rheology from GRACE and GPS ... - pdf éditeurAdobe Acrobat PDF Accuracy versus precision: a primer on GPS truth / D. Rutledge in GPS world, vol 21 n° 5 (May 2010)
[article]
Titre : Accuracy versus precision: a primer on GPS truth Type de document : Article/Communication Auteurs : D. Rutledge, Auteur Année de publication : 2010 Article en page(s) : pp 42 - 49 Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale
[Termes IGN] correction du signal
[Termes IGN] distribution de Gauss
[Termes IGN] erreur aléatoire
[Termes IGN] erreur systématique
[Termes IGN] précision du positionnement
[Termes IGN] signal GPSRésumé : (Editeur) All measurements contain errors. To extract the most useful amount of information from the measurements, the errors must be properly analyzed. Errors can be broadly grouped into two major categories: biases, which are systematic and which can be modeled in an equation describing the measurements, thereby removing or significantly reducing their effect; and noise or random error, each value of which cannot be modeled but whose statistical properties can be used to optimize the analysis results. Take GPS carrier-phase measurements, for example. It is a standard approach to collect measurements at a reference station and a target station and to form the double differences of the measurements between pairs of satellites and the pair of receivers. By so doing, the biases in the modeled measurements that are common to both receivers, such as residual satellite clock error, are canceled or significantly reduced. However, the random error in the measurements due to receiver thermal noise and the quasi-random effect of multipath cannot be differenced away. If we estimate the coordinates of the target receiver at each epoch of the measurements, how far will they be from the true coordinates? That depends on how well the biases were removed and the effects of random error. By comparing the results from many epochs of data, we might see that the coordinate values agree amongst themselves quite closely; they have high precision. But, due to some remaining bias, they are offset from the true value; their accuracy is low. Two different but complementary measures for assessing the quality of the results. In this month's column, we will examine the differences between the precision and accuracy of GPS-determined positions and, armed with a better understanding of these often confused terms, perhaps be less likely to abuse the truth in the business of GPS positioning. Copyright Questex Media Group Numéro de notice : A2010-166 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : sans Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=30361
in GPS world > vol 21 n° 5 (May 2010) . - pp 42 - 49[article]Exemplaires(1)
Code-barres Cote Support Localisation Section Disponibilité 067-2010051 RAB Revue Centre de documentation En réserve L003 Disponible GPS slant total electron content accuracy using the single layer model under different geomagnetic regions and ionospheric conditions / C. Brunini in Journal of geodesy, vol 84 n° 5 (May 2010)
[article]
Titre : GPS slant total electron content accuracy using the single layer model under different geomagnetic regions and ionospheric conditions Type de document : Article/Communication Auteurs : C. Brunini, Auteur ; F. Azpilicueta, Auteur Année de publication : 2010 Article en page(s) : pp 293 - 304 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale
[Termes IGN] erreur systématique
[Termes IGN] ionosphère
[Termes IGN] positionnement par GPS
[Termes IGN] teneur totale en électrons
[Termes IGN] traitement de données GNSSRésumé : (Auteur) The use of observations from the Global Positioning System (GPS) has significantly impacted the study of the ionosphere. As it is widely known, dual-frequency GPS observations can provide very precise estimation of the slant Total Electron Content (sTEC—the linear integral of the electron density along a ray-path) and that the precision level is bounded by the carrier-phase noise and multi-path effects on both frequencies. Despite its precision, GPS sTEC estimations can be systematically affected by errors in the estimation of the satellites and receivers by Inter-Frequency Biases (IFB) that are simultaneously determined with the sTEC. Thus, the ultimate accuracy of the GPS sTEC estimation is determined by the errors with which the IFBs are estimated. This contribution attempts to assess the accuracy of IFBs estimation techniques based on the single layer model for different ionospheric regions (low, mid and high magnetic latitude); different seasons (summer and winter solstices and spring and autumn equinoxes); different solar activity levels (high and low); and different geomagnetic conditions (quiet and very disturbed). The followed strategy relies upon the generation of a synthetic data set free of IFB, multi-path, measurement noise and of any other error source. Therefore, when a data set with such properties is used as the input of the IFB estimation algorithms, any deviation from zero on the estimated IFBs should be taken as indications of the errors introduced by the estimation technique. The truthfulness of this assessment work is warranted by the fact that the synthetic data sets resemble, as realistically as possible, the different conditions that may happen in the real ionosphere. The results of this work show that during the high solar activity period the accuracy for the estimated sTEC is approximately of 110 TECu for the low geomagnetic region and of 12.2 TECu for the mid-latitude. During low solar activity the accuracy can be assumed to be in the order of 12 TECu. For the geomagnetic high-disturbed period, the results show that the accuracy is degraded for those stations located over the region where the storm has the strongest impact, but for those stations over regions where the storm has a moderate effect, the accuracy is comparable to that obtained in the quiet period. Numéro de notice : A2010-182 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-010-0367-5 Date de publication en ligne : 29/01/2010 En ligne : https://doi.org/10.1007/s00190-010-0367-5 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=30377
in Journal of geodesy > vol 84 n° 5 (May 2010) . - pp 293 - 304[article]Exemplaires(1)
Code-barres Cote Support Localisation Section Disponibilité 266-2010051 SL Revue Centre de documentation Revues en salle Disponible Single receiver phase ambiguity resolution with GPS data / Willy I. Bertiger in Journal of geodesy, vol 84 n° 5 (May 2010)
[article]
Titre : Single receiver phase ambiguity resolution with GPS data Type de document : Article/Communication Auteurs : Willy I. Bertiger, Auteur ; Shailen Desai, Auteur ; Bruce J. Haines, Auteur ; et al., Auteur Année de publication : 2010 Article en page(s) : pp 327 - 337 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale
[Termes IGN] données GPS
[Termes IGN] GIPSY-OASIS
[Termes IGN] mesurage de phase
[Termes IGN] phase GPS
[Termes IGN] positionnement cinématique
[Termes IGN] positionnement par GPS
[Termes IGN] positionnement ponctuel précis
[Termes IGN] positionnement statique
[Termes IGN] résolution d'ambiguïté
[Termes IGN] traitement de données GNSSRésumé : (Auteur) Global positioning system (GPS) data processing algorithms typically improve positioning solution accuracy by fixing double-differenced phase bias ambiguities to integer values. These “double-difference ambiguity resolution” methods usually invoke linear combinations of GPS carrier phase bias estimates from pairs of transmitters and pairs of receivers, and traditionally require simultaneous measurements from at least two receivers. However, many GPS users point position a single local receiver, based on publicly available solutions for GPS orbits and clocks. These users cannot form double differences. We present an ambiguity resolution algorithm that improves solution accuracy for single receiver point-positioning users. The algorithm processes dual- frequency GPS data from a single receiver together with wide-lane and phase bias estimates from the global network of GPS receivers that were used to generate the orbit and clock solutions for the GPS satellites. We constrain (rather than fix) linear combinations of local phase biases to improve compatibility with global phase bias estimates. For this precise point positioning, no other receiver data are required. When tested, our algorithm significantly improved repeatability of daily estimates of ground receiver positions, most notably in the east component by approximately 30% with respect to the nominal case wherein the carrier biases are estimated as real values. In this “static” test for terrestrial receiver positions, we achieved daily repeatability of 1.9, 2.1 and 6.0 mm in the east, north and vertical (ENV) components, respectively. For kinematic solutions, ENV repeatability is 7.7, 8.4, and 11.7 mm, respectively, representing improvements of 22, 8, and 14% with respect to the nominal. Results from precise orbit determination of the twin GRACE satellites demonstrated that the inter-satellite baseline accuracy improved by a factor of three, from 6 to 2 mm up to a long-term bias. Jason-2/Ocean Surface Topography Mission precise orbit determination tests results implied radial orbit accuracy significantly below the 10 mm level. Stability of time transfer, in low-Earth orbit, improved from 40 to 7 ps. We produced these results by applying this algorithm within the Jet Propulsion Laboratory’s (JPL’s) GIPSY/OASIS software package and using JPL’s orbit and clock products for the GPS constellation. These products now include a record of the wide-lane and phase bias estimates from the underlying global network of GPS stations. This implies that all GIPSY–OASIS positioning users can now benefit from this capability to perform single-receiver ambiguity resolution. Numéro de notice : A2010-185 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-010-0371-9 Date de publication en ligne : 21/03/2010 En ligne : https://doi.org/10.1007/s00190-010-0371-9 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=30380
in Journal of geodesy > vol 84 n° 5 (May 2010) . - pp 327 - 337[article]Exemplaires(1)
Code-barres Cote Support Localisation Section Disponibilité 266-2010051 SL Revue Centre de documentation Revues en salle Disponible Impact of regional reference frame definition on geodynamic interpretations / Juliette Legrand in Journal of geodynamics, vol 49 n° 3-4 (April 2010)PermalinkHomogeneous zenith total delay parameter estimation from European permanent GNSS sites / Wolfgang Söhne in Bulletin of geodesy and geomatics BGG, vol 69 n° 1 (March 2010)PermalinkHybrid positioning: a prototype system for navigation in GPS-challenged environments / Chris Rizos in GPS world, vol 21 n° 3 (March 2010)PermalinkReady to navigate: a methodology for the estimation of the time-to-first-fix / M. Anghileri in Inside GNSS, vol 5 n° 2 (March - April 2010)PermalinkWide-area RTK: high precision positioning on a continental scale / Manuel Hernández-Pajares in Inside GNSS, vol 5 n° 2 (March - April 2010)PermalinkAnalyse combinée de données GPS et lidar Raman acquises lors de la campagne COPS pour l'amélioration du positionnement vertical par GPS / Martin Blocquaux (2010)PermalinkCombined integrity of GPS and Galileo / F. Kneissl in Inside GNSS, vol 5 n° 1 (January - February 2010)PermalinkGlobal gravity field determination using the GPS measurements made onboard the low Earth orbiting satellite CHAMP / Lars Prange (2010)PermalinkMéthodologie GPS, mesure des déformations verticales et humidité atmosphérique / Marie-Noëlle Bouin (2010)PermalinkModernization milestone: the GPS civil monitoring performance specification / T. Nagle in Inside GNSS, vol 5 n° 1 (January - February 2010)PermalinkTesting software receivers / A. Mitelman in GPS world, vol 20 n° 12 (December 2009)PermalinkHomogeneous reprocessing of the EUREF permanent network : first experiences and comparisons / A. Kenyeres in Bulletin of geodesy and geomatics BGG, vol 68 n° 3 (October 2009)PermalinkInvestigating tropospheric effects and seasonal position variations in GPS and DORIS time-series from the Nepal Himalaya / Mireille Flouzat in Geophysical journal international, vol 178 n° 3 (September 2009)PermalinkOne year in orbit: GIOVE-B E1 CBOC signal quality assessment / M. Sollner in GPS world, vol 20 n° 9 (September 2009)PermalinkRemote sensing with reflected signals: GNSS-R data processing software and test analysis / D. Yang in Inside GNSS, vol 4 n° 5 (September - October 2009)PermalinkSignal authentication: a secure civil GNSS for today / S. Lo in Inside GNSS, vol 4 n° 5 (September - October 2009)PermalinkThe SVN49 pseudorange error / R. Langley in GPS world, vol 20 n° 8 (August 2009)PermalinkArchitecture for a future C-band/L-band GNSS mission : Part 2 signal considerations and related user terminal aspects / José Avila-Rodriguez in Inside GNSS, vol 4 n° 4 (July - August 2009)PermalinkMaking sense of inter-signal corrections: accounting for GPS satellite calibration parameters in legacy and modernized ionosphere correction algorithms / Avram Tetewsky in Inside GNSS, vol 4 n° 4 (July - August 2009)PermalinkGNSS update: frequenting frequencies / Huibert-Jan Lekkerkerk in Geoinformatics, vol 12 n° 4 (01/06/2009)Permalink