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Geodetic VLBI for precise orbit determination of Earth satellites: a simulation study / Grzegorz Klopotek in Journal of geodesy, vol 94 n° 6 (June 2020)
Titre : Geodetic VLBI for precise orbit determination of Earth satellites: a simulation study Type de document : Article/Communication Auteurs : Grzegorz Klopotek, Auteur ; Thomas Hobiger, Auteur ; Rüdiger Haas, Auteur ; Toshimichi Otsubo, Auteur Année de publication : 2020 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale
[Termes descripteurs IGN] constellation GNSS
[Termes descripteurs IGN] données Galileo
[Termes descripteurs IGN] données Lageos
[Termes descripteurs IGN] données VGOS
[Termes descripteurs IGN] géocentre
[Termes descripteurs IGN] interférométrie à très grande base
[Termes descripteurs IGN] méthode de Monte-Carlo
[Termes descripteurs IGN] orbitographie
[Termes descripteurs IGN] paramètres d'orientation de la Terre
[Termes descripteurs IGN] quasar
[Termes descripteurs IGN] rotation de la TerreRésumé : (auteur) Recent efforts of tracking low Earth orbit and medium Earth orbit (MEO) satellites using geodetic very long baseline interferometry (VLBI) raise questions on the potential of this novel observation concept for space geodesy. Therefore, we carry out extensive Monte Carlo simulations in order to investigate the feasibility of geodetic VLBI for precise orbit determination (POD) of MEO satellites and assess the impact of quality and quantity of satellite observations on the derived geodetic parameters. The MEO satellites are represented in our study by LAGEOS-1/-2 and a set of Galileo satellites. The concept is studied on the basis of 3-day solutions in which satellite observations are included into real schedules of the continuous geodetic VLBI campaign 2017 (CONT17) as well as simulated schedules concerning the next-generation VLBI system, known as the VLBI Global Observing System (VGOS). Our results indicate that geodetic VLBI can perform on a comparable level as other space-geodetic techniques concerning POD of MEO satellites. For an assumed satellite observation precision better than 14.1 mm (47 ps), an average 3D orbit precision of 2.0 cm and 6.3 cm is found for schedules including LAGEOS-1/-2 and Galileo satellites, respectively. Moreover, geocenter offsets, which were so far out of scope for the geodetic VLBI analysis, are close to the detection limit for the simulations concerning VGOS observations of Galileo satellites, with the potential to further enhance the results. Concerning the estimated satellite orbits, VGOS leads to an average precision improvement of 80% with respect to legacy VLBI. In absolute terms and for satellite observation precision of 14.1 mm (47 ps), this corresponds to an average value of 17 mm and 7 mm concerning the 3D orbit scatter and precision of geocenter components, respectively. As shown in this study, a poor satellite geometry can degrade the derived Earth rotation parameters and VLBI station positions, compared to the quasar-only reference schedules. Therefore, careful scheduling of both quasar and satellite observations should be performed in order to fully benefit from this novel observation concept. Numéro de notice : A2020-342 Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-020-01381-9 date de publication en ligne : 11/06/2020 En ligne : https://doi.org/10.1007/s00190-020-01381-9 Format de la ressource électronique : url article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=95221
in Journal of geodesy > vol 94 n° 6 (June 2020)[article]
Titre : Impact of network constraining on the terrestrial reference frame realization based on SLR observations to LAGEOS Type de document : Article/Communication Auteurs : R. Zajdel, Auteur ; Krzysztof Sosnica, Auteur ; M. Drożdżewski, Auteur ; Grzegorz Bury, Auteur ; D. Strugarek, Auteur Année de publication : 2019 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale
[Termes descripteurs IGN] géocentre
[Termes descripteurs IGN] International Terrestrial Reference Frame
[Termes descripteurs IGN] Lageos
[Termes descripteurs IGN] réseau de contraintes
[Termes descripteurs IGN] rotation de la Terre
[Termes descripteurs IGN] station TLS (télémétrie)
[Termes descripteurs IGN] système de référence géodésique
[Termes descripteurs IGN] système de référence local
[Termes descripteurs IGN] télémétrie laser sur satellite
[Termes descripteurs IGN] transformation de HelmertRésumé : (auteur)
The Satellite Laser Ranging (SLR) network struggles with some major limitations including an inhomogeneous global station distribution and uneven performance of SLR sites. The International Laser Ranging Service (ILRS) prepares the time-variable list of the most well-performing stations denoted as ‘core sites’ and recommends using them for the terrestrial reference frame (TRF) datum realization in SLR processing. Here, we check how different approaches of the TRF datum realization using minimum constraint conditions (MCs) and the selection of datum-defining stations affect the estimated SLR station coordinates, the terrestrial scale, Earth rotation parameters (ERPs), and geocenter coordinates (GCC). The analyses are based on the processing of the SLR observations to LAGEOS-1/-2 collected between 2010 and 2018. We show that it is essential to reject outlying stations from the reference frame realization to maintain a high quality of SLR-based products. We test station selection criteria based on the Helmert transformation of the network w.r.t. the a priori SLRF2014 coordinates to reject misbehaving stations from the list of datum-defining stations. The 25 mm threshold is optimal to eliminate the epoch-wise temporal deviations and to provide a proper number of datum-defining stations. According to the station selection algorithm, we found that some of the stations that are not included in the list of ILRS core sites could be taken into account as potential core stations in the TRF datum realization. When using a robust station selection for the datum definition, we can improve the station coordinate repeatability by 8%, 4%, and 6%, for the North, East and Up components, respectively. The global distribution of datum-defining stations is also crucial for the estimation of ERPs and GCC. When excluding just two core stations from the SLR network, the amplitude of the annual signal in the GCC estimates is changed by up to 2.2 mm, and the noise of the estimated pole coordinates is substantially increased.Numéro de notice : A2019-610 Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-019-01307-0 date de publication en ligne : 17/10/2019 En ligne : https://doi.org/10.1007/s00190-019-01307-0 Format de la ressource électronique : url article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=94794
in Journal of geodesy > vol 93 n°11 (November 2019)[article]
Titre : Troposphere delay modeling with horizontal gradients for satellite laser ranging Type de document : Article/Communication Auteurs : M. Drożdżewski, Auteur ; Krzysztof Sosnica, Auteur ; Florian Zus, Auteur ; Kyriakos Balidakis, Auteur Année de publication : 2019 Note générale : bibbliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale
[Termes descripteurs IGN] angle vertical
[Termes descripteurs IGN] coordonnées polaires
[Termes descripteurs IGN] dissymétrie
[Termes descripteurs IGN] erreur systématique
[Termes descripteurs IGN] géocentre
[Termes descripteurs IGN] gradient de troposphère
[Termes descripteurs IGN] interférométrie à très grande base
[Termes descripteurs IGN] Lageos
[Termes descripteurs IGN] retard troposphérique
[Termes descripteurs IGN] Sentinel-3
[Termes descripteurs IGN] station TLS (télémétrie)
[Termes descripteurs IGN] télémètre laser sur satelliteRésumé : (auteur) Satellite laser ranging (SLR) constitutes a fundamental space geodetic technique providing global geodetic parameters, such as geocenter coordinates, Earth rotation parameters, and low-degree gravity field coefficients. The tropospheric delay correction is one of the crucial corrections that have to be taken into account when processing SLR data. Current conventional models of the troposphere delays assume a full symmetry of the atmosphere above SLR stations. Neglecting horizontal gradients in SLR solutions introduces a systematic error in SLR products, especially for the observations at low elevation angles, and leads to a deterioration of the consistency between SLR and other space geodetic techniques, such as global navigational satellite systems and very-long-baseline interferometry. We derive new mapping function coefficients, as well as first- and second-order horizontal gradients, all of which are based on numerical weather models, in order to properly consider the azimuthal asymmetry in SLR solutions. We test the enhanced mapping function and horizontal gradients on the solutions based on 11 years of SLR observations to LAGEOS-1/2 satellites and 1 year of SLR observations to Sentinel-3A. The consideration of azimuthal asymmetry of the atmosphere above the SLR stations has a systematic effect on SLR-derived products, such as station and geocenter coordinates and pole coordinates. Horizontal gradients in SLR solutions improve the consistency between SLR-derived pole coordinates and the combined IERS-C04 series by means of reducing the offset for the X and Y pole coordinates by 20 μas. The second-order horizontal gradients are negligible in SLR solutions; thus, including first-order gradients is sufficient for SLR solutions. Numéro de notice : A2019-607 Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-019-01287-1 date de publication en ligne : 22/08/2019 En ligne : https://doi.org/10.1007/s00190-019-01287-1 Format de la ressource électronique : url article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=94790
in Journal of geodesy > vol 93 n°10 (October 2019)[article]
Titre : A Terrestrial Reference Frame realised on the observation level using a GPS-LEO satellite constellation Type de document : Article/Communication Auteurs : Daniel Koenig, Auteur Année de publication : 2018 Article en page(s) : pp 1299 - 1312 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Systèmes de référence et réseaux
[Termes descripteurs IGN] champ de pesanteur terrestre
[Termes descripteurs IGN] données GPS
[Termes descripteurs IGN] données GRACE
[Termes descripteurs IGN] géocentre
[Termes descripteurs IGN] International Terrestrial Reference Frame
[Termes descripteurs IGN] transformation de HelmertRésumé : (Auteur) Applying a one-step integrated process, i.e. by simultaneously processing all data and determining all satellite orbits involved, a Terrestrial Reference Frame (TRF) consisting of a geometric as well as a dynamic part has been determined at the observation level using the EPOS-OC software of Deutsches GeoForschungsZentrum. The satellite systems involved comprise the Global Positioning System (GPS) as well as the twin GRACE spacecrafts. Applying a novel approach, the inherent datum defect has been overcome empirically. In order not to rely on theoretical assumptions this is done by carrying out the TRF estimation based on simulated observations and using the associated satellite orbits as background truth. The datum defect is identified here as the total of all three translations as well as the rotation about the z-axis of the ground station network leading to a rank-deficient estimation problem. To rectify this singularity, datum constraints comprising no-net translation (NNT) conditions in x, y, and z as well as a no-net rotation (NNR) condition about the z-axis are imposed. Thus minimally constrained, the TRF solution covers a time span of roughly a year with daily resolution. For the geometric part the focus is put on Helmert transformations between the a priori and the estimated sets of ground station positions, and the dynamic part is represented by gravity field coefficients of degree one and two. The results of a reference solution reveal the TRF parameters to be estimated reliably with high precision. Moreover, carrying out a comparable two-step approach using the same data and models leads to parameters and observational residuals of worse quality. A validation w.r.t. external sources shows the dynamic origin to coincide at a level of 5 mm or better in x and y, and mostly better than 15 mm in z. Comparing the derived GPS orbits to IGS final orbits as well as analysing the SLR residuals for the GRACE satellites reveals an orbit quality on the few cm level. Additional TRF test solutions demonstrate that K-Band Range-Rate observations between both GRACE spacecrafts are crucial for accurately estimating the dynamic frame’s orientation, and reveal the importance of the NNT- and NNR-conditions imposed for estimating the components of the dynamic geocenter. Numéro de notice : A2018-464 Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-018-1121-7 date de publication en ligne : 27/02/2018 En ligne : https://doi.org/10.1007/s00190-018-1121-7 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=91063
in Journal of geodesy > vol 92 n° 11 (November 2018) . - pp 1299 - 1312[article]
Titre : Dependency of geodynamic parameters on the GNSS constellation Type de document : Article/Communication Auteurs : Stefano Scaramuzza, Auteur ; Rolf Dach, Auteur ; Gerhard Beutler, Auteur ; Daniel Arnold, Auteur ; Andreja Sušnik, Auteur ; Adrian Jäggi, Auteur Année de publication : 2018 Article en page(s) : pp 93 - 104 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique
[Termes descripteurs IGN] constellation GLONASS
[Termes descripteurs IGN] constellation GPS
[Termes descripteurs IGN] géocentre
[Termes descripteurs IGN] mouvement du pôle
[Termes descripteurs IGN] orbite
[Termes descripteurs IGN] série temporelleRésumé : (Auteur) Significant differences in time series of geodynamic parameters determined with different Global Navigation Satellite Systems (GNSS) exist and are only partially explained. We study whether the different number of orbital planes within a particular GNSS contributes to the observed differences by analyzing time series of geocenter coordinates (GCCs) and pole coordinates estimated from several real and virtual GNSS constellations: GPS, GLONASS, a combined GPS/GLONASS constellation, and two virtual GPS sub-systems, which are obtained by splitting up the original GPS constellation into two groups of three orbital planes each. The computed constellation-specific GCCs and pole coordinates are analyzed for systematic differences, and their spectral behavior and formal errors are inspected. We show that the number of orbital planes barely influences the geocenter estimates. GLONASS’ larger inclination and formal errors of the orbits seem to be the main reason for the initially observed differences. A smaller number of orbital planes may lead, however, to degradations in the estimates of the pole coordinates. A clear signal at three cycles per year is visible in the spectra of the differences between our estimates of the pole coordinates and the corresponding IERS 08 C04 values. Combinations of two 3-plane systems, even with similar ascending nodes, reduce this signal. The understanding of the relation between the satellite constellations and the resulting geodynamic parameters is important, because the GNSS currently under development, such as the European Galileo and the medium Earth orbit constellation of the Chinese BeiDou system, also consist of only three orbital planes. Numéro de notice : A2018-012 Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-017-1047-5 En ligne : https://doi.org/10.1007/s00190-017-1047-5 Format de la ressource électronique : URL Article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=89055
in Journal of geodesy > vol 92 n° 1 (January 2018) . - pp 93 - 104[article]PermalinkPermalinkPermalinkPermalinkPermalinkPermalinkCombination of GNSS and SLR measurements : contribution to the realization of the terrestrial reference frame / Sara Bruni (2016)
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