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Ajouter le résultat dans votre panierImpacts of real-time satellite clock errors on GPS precise point positioning-based troposphere zenith delay estimation / Junbo Shi in Journal of geodesy, vol 89 n° 8 (August 2015)
Titre : Impacts of real-time satellite clock errors on GPS precise point positioning-based troposphere zenith delay estimation Type de document : Article/Communication Auteurs : Junbo Shi, Auteur ; Chaoqian Xu, Auteur ; Yihe Li, Auteur ; Yang Gao, Auteur Année de publication : 2015 Article en page(s) : pp 747-756 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Termes IGN] erreur corrélée au temps
[Termes IGN] horloge atomique
[Termes IGN] orbite précise
[Termes IGN] positionnement cinématique en temps réel
[Termes IGN] positionnement par GPS
[Termes IGN] positionnement ponctuel précis
[Termes IGN] retard troposphérique zénithal
[Termes IGN] temps réel
[Vedettes matières IGN] Traitement de données GNSSRésumé : (auteur) Global Positioning System (GPS) has become a cost-effective tool to determine troposphere zenith total delay (ZTD) with accuracy comparable to other atmospheric sensors such as the radiosonde, the water vapor radiometer, the radio occultation and so on. However, the high accuracy of GPS troposphere ZTD estimates relies on the precise satellite orbit and clock products available with various latencies. Although the International GNSS Service (IGS) can provide predicted orbit and clock products for real-time applications, the predicted clock accuracy of 3 ns cannot always guarantee the high accuracy of troposphere ZTD estimates. Such limitations could be overcome by the use of the newly launched IGS real-time service which provides ∼5 cm orbit and 0.2–1.0 ns (an equivalent range error of 6–30 cm) clock products in real time. Considering the relatively larger magnitude of the clock error than that of the orbit error, this paper investigates the effect of real-time satellite clock errors on the GPS precise point positioning (PPP)-based troposphere ZTD estimation. Meanwhile, how the real-time satellite clock errors impact the GPS PPP-based troposphere ZTD estimation has also been studied to obtain the most precise ZTD solutions. First, two types of real-time satellite clock products are assessed with respect to the IGS final clock product in terms of accuracy and precision. Second, the real-time GPS PPP-based troposphere ZTD estimation is conducted using data from 34 selected IGS stations over three independent weeks in April, July and October, 2013. Numerical results demonstrate that the precision, rather than the accuracy, of the real-time satellite clock products impacts the real-time PPP-based ZTD solutions more significantly. In other words, the real-time satellite clock product with better precision leads to more precise real-time PPP-based troposphere ZTD solutions. Therefore, it is suggested that users should select and apply real-time satellite products with better clock precision to obtain more consistent real-time PPP-based ZTD solutions. Numéro de notice : A2015-374 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-015-0811-7 Date de publication en ligne : 04/04/2015 En ligne : https://doi.org/10.1007/s00190-015-0811-7 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=76852
in Journal of geodesy > vol 89 n° 8 (August 2015) . - pp 747-756[article]
Titre : Alternative validation method of satellite gradiometric data by integral transform of satellite altimetry data Type de document : Article/Communication Auteurs : Michal Šprlák, Auteur ; Eliška Hamáčková, Auteur ; Pavel Novák, Auteur Année de publication : 2015 Article en page(s) : pp 757 - 773 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique
[Termes IGN] altimétrie satellitaire par radar
[Termes IGN] champ de gravitation
[Termes IGN] données GOCE
[Termes IGN] équation intégrale
[Termes IGN] gradient de gravitation
[Termes IGN] gradiométrie
[Termes IGN] potentiel de pesanteur terrestreRésumé : (auteur) Integral transforms of the disturbing gravitational potential derived from satellite altimetry onto satellite gradiometric data are formulated, investigated and applied in this article. First, corresponding differential operators, that relate the disturbing gravitational potential to the six components of the disturbing gradiometric tensor in the spherical local north-oriented frame, are applied to the spherical Abel-Poisson integral equation. This yields six new integral equations for which respective kernel functions are given in both spectral and spatial forms. Second, truncation error formulas for each of the integral transforms are provided in the spectral form. Also expressions for the corresponding truncation error coefficients are derived. Third, practical estimators for evaluation of the disturbing gravitational gradients are formulated, and their correctness and expected accuracy are investigated. Finally, the practical estimators are applied for validation of a sample of the gradiometric data provided by the GOCE satellite mission. Obtained results demonstrate applicability of the new apparatus as an alternative validation method of the satellite gravitational gradients. Numéro de notice : A2015-375 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-015-0813-5 Date de publication en ligne : 24/04/2015 En ligne : http://dx.doi.org/10.1007/s00190-015-0813-5 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=76853
in Journal of geodesy > vol 89 n° 8 (August 2015) . - pp 757 - 773[article]
Titre : CODE’s new solar radiation pressure model for GNSS orbit determination Type de document : Article/Communication Auteurs : Daniel Arnold, Auteur ; Michael Meindl, Auteur ; Gerhard Beutler, Auteur ; et al., Auteur Année de publication : 2015 Article en page(s) : pp 775 - 791 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Technologies spatiales
[Termes IGN] géocentre
[Termes IGN] International GNSS Service
[Termes IGN] modèle d'orbite
[Termes IGN] orbitographie
[Termes IGN] rayonnement solaire
[Termes IGN] récepteur GLONASS
[Termes IGN] récepteur GPS
[Termes IGN] rotation de la TerreRésumé : (auteur) The Empirical CODE Orbit Model (ECOM) of the Center for Orbit Determination in Europe (CODE), which was developed in the early 1990s, is widely used in the International GNSS Service (IGS) community. For a rather long time, spurious spectral lines are known to exist in geophysical parameters, in particular in the Earth Rotation Parameters (ERPs) and in the estimated geocenter coordinates, which could recently be attributed to the ECOM. These effects grew creepingly with the increasing influence of the GLONASS system in recent years in the CODE analysis, which is based on a rigorous combination of GPS and GLONASS since May 2003. In a first step we show that the problems associated with the ECOM are to the largest extent caused by the GLONASS, which was reaching full deployment by the end of 2011. GPS-only, GLONASS-only, and combined GPS/GLONASS solutions using the observations in the years 2009–2011 of a global network of 92 combined GPS/GLONASS receivers were analyzed for this purpose. In a second step we review direct solar radiation pressure (SRP) models for GNSS satellites. We demonstrate that only even-order short-period harmonic perturbations acting along the direction Sun-satellite occur for GPS and GLONASS satellites, and only odd-order perturbations acting along the direction perpendicular to both, the vector Sun-satellite and the spacecraft’s solar panel axis. Based on this insight we assess in the third step the performance of four candidate orbit models for the future ECOM. The geocenter coordinates, the ERP differences w. r. t. the IERS 08 C04 series of ERPs, the misclosures for the midnight epochs of the daily orbital arcs, and scale parameters of Helmert transformations for station coordinates serve as quality criteria. The old and updated ECOM are validated in addition with satellite laser ranging (SLR) observations and by comparing the orbits to those of the IGS and other analysis centers. Based on all tests, we present a new extended ECOM which substantially reduces the spurious signals in the geocenter coordinate z (by about a factor of 2–6), reduces the orbit misclosures at the day boundaries by about 10 %, slightly improves the consistency of the estimated ERPs with those of the IERS 08 C04 Earth rotation series, and substantially reduces the systematics in the SLR validation of the GNSS orbits. Numéro de notice : A2015-376 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-015-0814-4 Date de publication en ligne : 12/05/2015 En ligne : https://doi.org/10.1007/s00190-015-0814-4 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=76854
in Journal of geodesy > vol 89 n° 8 (August 2015) . - pp 775 - 791[article]
Titre : Single-frequency precise point positioning: an analytical approach Type de document : Article/Communication Auteurs : Oskar Sterle, Auteur ; Bojan Stopar, Auteur ; Polona Pavlovčič Prešeren, Auteur Année de publication : 2015 Article en page(s) : pp 793-810 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Termes IGN] analyse comparative
[Termes IGN] analyse de données
[Termes IGN] coordonnées géographiques
[Termes IGN] horloge
[Termes IGN] positionnement ponctuel précis
[Termes IGN] propagation troposphérique
[Termes IGN] récepteur monofréquence
[Termes IGN] station permanente
[Termes IGN] transformation de Helmert
[Vedettes matières IGN] Traitement de données GNSSRésumé : (auteur) An analytical approach to single-frequency precise point positioning (PPP) is discussed in this paper. To obtain highest precision results, all biases must be eliminated or modelled to centimetre level. The use of the GRAPHIC ionosphere-free linear combination that is based on single-frequency phase and code observations eliminates the ionosphere bias; however, the rank deficient Gauss–Markov model is obtained. We explicitly determine rank deficiency of a Gauss–Markov model as a number of all ambiguity clusters, each of them defined as a set of all ambiguities overlapping in time. On the basis of S-transformation we prove that the single-frequency PPP represents an unbiased estimator for station coordinates and troposphere parameters, while it presents a biased estimator for ambiguities and receiver-clock error parameters. Additionally we describe the estimable parameters in each ambiguity cluster as the differences between ambiguity parameters and the sum of receiver-clock parameters with one of the ambiguities. We also show that any other particular solution on the basis of S-transformation is obtained only when the common least-squares estimation in single step is applied. The recursive least-squares estimation with parameter pre-elimination only determines the vector of unknowns as possible to transform through S-transformation, whereas the same does not hold for the cofactor matrix of unknowns. For a case study, we present our method on GPS data from 19 permanent stations (14 IGS and 5 EPN) in Europe, for 89 consecutive days in the beginning of 2013. The static case study revealed the precision of daily coordinates as 7.6, 11.7 and 19.6 mm for N, E and U, respectively. The accuracies of the N, E and U components were determined as 6.9, 13.5 and 31.4 mm, respectively, and were calculated using the Helmert transformation of weighted-mean daily single-frequency PPP and IGb08 coordinates. The estimated convergence times were relatively diverse, expanding from 1.75 h (CAGL) to 5.25 h (GRAZ) for the horizontal position with the 10-cm precision threshold, and from 1.00 h (GRAS) to 3.25 h (BZRG) for the height component with a 20-cm precision threshold. The convergence times were shown to be strongly correlated to the remaining unmodelled biases in the GRAPHIC linear combination, primarily with multipath, where the correlation coefficient for the horizontal position was determined as ρP = 0.68 and for height as ρU = 0.85. The comparison to the model where raw observations are used (C, L) and where the ionosphere bias is mitigated with global ionosphere models (GIM) revealed the supremacy of the proposed single-frequency PPP method based on the GRAPHIC linear combination in both the static and the semi-kinematic case study. In the static case study, the proposed single-frequency PPP model was superior both in terms of precision and accuracy. In the semi-kinematic case study, the usage of raw observations with GIM would improve results only when multipath and noise of code observations would prevail over the remaining ionosphere bias, i.e. after applying GIM. Numéro de notice : A2015-377 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-015-0816-2 Date de publication en ligne : 29/04/2015 En ligne : https://doi.org/10.1007/s00190-015-0816-2 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=76855
in Journal of geodesy > vol 89 n° 8 (August 2015) . - pp 793-810[article]
Titre : The Fresnel–Fizeau effect and the atmospheric time delay in geodetic VLBI Type de document : Article/Communication Auteurs : S. M. Kopeikin, Auteur ; B. Han, Auteur Année de publication : 2015 Article en page(s) : pp 829 - 834 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement du signal
[Termes IGN] correction atmosphérique
[Termes IGN] données ITGB
[Termes IGN] interférométrie à très grande base
[Termes IGN] International Earth Rotation Service
[Termes IGN] rayonnement électromagnétique
[Termes IGN] retard troposphériqueRésumé : (auteur) The Fresnel–Fizeau effect is a special relativistic effect that makes the speed of light dependent on the velocity of a transparent, moving medium. We present a theoretical formalism for discussing propagation of electromagnetic signals through the moving Earth atmosphere taking into account the Fresnel–Fizeau effect. It provides the rigorous relativistic derivation of the atmospheric time delay equation in the consensus model of geodetic VLBI observations which has never been published before. The paper confirms the atmospheric time delay of the consensus VLBI model used in IERS standards and provides a firm theoretical basis for calculation of even more subtle relativistic corrections. Numéro de notice : A2015-378 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-015-0812-6 Date de publication en ligne : 24/04/2015 En ligne : https://doi.org/10.1007/s00190-015-0812-6 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=76856
in Journal of geodesy > vol 89 n° 8 (August 2015) . - pp 829 - 834[article]
Titre : The status of measurement of the Mediterranean mean dynamic topography by geodetic techniques Type de document : Article/Communication Auteurs : Philip L. Woodworth, Auteur ; Médéric Gravelle, Auteur ; Marta Marcos, Auteur ; Guy Wöppelmann Année de publication : 2015 Article en page(s) : pp 811 - 827 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale
[Termes IGN] données marégraphiques
[Termes IGN] géoïde local
[Termes IGN] hauteur ellipsoïdale
[Termes IGN] Méditerranée, mer
[Termes IGN] océanographie dynamique
[Termes IGN] océanographie spatiale
[Termes IGN] positionnement par GPS
[Termes IGN] surface de la merRésumé : (auteur) We review the measurement of the mean dynamic topography (MDT) of the Mediterranean using ellipsoidal heights of sea level at discrete tide gauge locations, and across the entire basin using satellite altimetry, subtracting estimates of the geoid obtained from recent models. This ‘geodetic approach’ to the determination of the MDT can be compared to the independent ‘ocean approach’ that involves the use of in situ oceanographic measurements and ocean modelling. We demonstrate that with modern geoid and ocean models there is an encouraging level of consistency between the two sets of MDTs. In addition, we show how important geodetic MDT information can be in judging between existing global ocean circulation models, and in providing insight for the development of new ones. The review makes clear the major limitations in Mediterranean data sets that prevent a more complete validation, including the need for improved geoid models of high spatial resolution and accuracy. Suggestions are made on how a greater amount of reliable geo-located tide gauge information can be obtained in the future. Numéro de notice : A2015-423 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-015-0817-1 Date de publication en ligne : 01/05/2015 En ligne : https://doi.org/10.1007/s00190-015-0817-1 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=77009
in Journal of geodesy > vol 89 n° 8 (August 2015) . - pp 811 - 827[article]
