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Self-consistent determination of the Earth’s GM, geocenter motion and figure axis orientation / Alexandre Couhert in Journal of geodesy, vol 94 n° 12 (December 2020)  

Public [article]  inJournal of geodesy > vol 94 n° 12 (December 2020) . - n° 113 Titre : Self-consistent determination of the Earth’s GM, geocenter motion and figure axis orientation Type de document : Article/Communication Auteurs : Alexandre Couhert, Auteur ; Christian Bizouard, Auteur ; F. Mercier, Auteur ; Kristel Chanard , Auteur ; Marianne Greff-Lefftz, Auteur ; Pierre Exertier, Auteur Année de publication : 2020 Projets : 1-Pas de projet / Article en page(s) : n° 113 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique [Termes IGN] données Ajisai [Termes IGN] données Jason [Termes IGN] données Lageos [Termes IGN] données LARES [Termes IGN] données Starlette [Termes IGN] données Stella [Termes IGN] données TLS (télémétrie) [Termes IGN] erreur de modèle [Termes IGN] harmonique sphérique [Termes IGN] incertitude géométrique [Termes IGN] mouvement du géocentre [Termes IGN] surface de la mer Résumé : (auteur) The very low-degree Earth’s gravity coefficients, associated with the largest-scale mass redistribution in the Earth’s fluid envelope (atmosphere, oceans and continental hydrology), are the most poorly known. In particular, the first three degree geopotential terms are important, as they relate to intrinsic Earth’s mass references: gravitational coefficient (GM) of the Earth (degree 0), geocenter motion (degree 1), Earth’s figure axis orientation (degree 2). This paper presents a self-consistent determination of these three properties of the Earth. The main objective is to deal with the remaining sources of altimetry satellite orbit uncertainties affecting the fundamental record of sea surface height measurements. The analysis identifies the modeling errors, which should be mitigated when estimating the geocenter coordinates from Satellite Laser Ranging (SLR) observations. The long-term behavior of the degree-0 and -2 spherical harmonics is also observed over the 34-year period 1984–2017 from the long-time history of satellite laser tracking to geodetic spherical satellites. From the analysis of the evolution of these two coefficients, constraints regarding the Earth’s rheology and uncertainties in the value of GM could be inferred. Overall, the influence of the orbit characteristics, SLR station ranging/position biases and satellite signature effects, measurement modeling errors (tropospheric corrections, non-tidal deformations) are also discussed. Numéro de notice : A2020-330 Affiliation des auteurs : UMR IPGP-Géod+Ext (2020- ) Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-020-01450-z Date de publication en ligne : 18/11/2020 En ligne : https://doi.org/10.1007/s00190-020-01450-z Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=96858 [article]

Center-of-mass corrections for sub-cm-precision laser-ranging targets: Starlette, Stella and LARES / Toshimichi Otsubo in Journal of geodesy, vol 89 n° 4 (April 2015)  

Public [article]  inJournal of geodesy > vol 89 n° 4 (April 2015) . - pp 303 - 312 Titre : Center-of-mass corrections for sub-cm-precision laser-ranging targets: Starlette, Stella and LARES Type de document : Article/Communication Auteurs : Toshimichi Otsubo, Auteur ; Robert A. Sherwood, Auteur ; Graham M. Appleby, Auteur ; et al., Auteur Année de publication : 2015 Article en page(s) : pp 303 - 312 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale [Termes IGN] données LARES [Termes IGN] données Starlette [Termes IGN] données Stella [Termes IGN] géodésie physique [Termes IGN] masse de la Terre [Termes IGN] précision des données [Termes IGN] télémétrie laser sur satellite Résumé : (auteur) To realize the full potential of satellite laser ranging for accurate geodesy, it is crucial that all systematic effects in the measurements are taken into account. This paper derives new values for the so-called center-of-mass corrections for three geodetic satellites that are regularly tracked and used in geodetic studies. Optical responses of the twin satellites, Starlette and Stella, and the LARES satellite are retrieved from kHz single-photon laser-ranging data observed at Herstmonceux and Potsdam. The detection timing inside single-photon systems, C-SPAD-based systems and photomultiplier-based systems is numerically simulated, and the center-of-mass corrections are derived to be in the range of 74 to 82 mm for Starlette and Stella, and 127–135 mm for LARES. The system dependence is below 1 cm, but should not be ignored for millimeter accuracy. The longtime standard center-of-mass correction 75 mm of Starlette and Stella is revealed to be too small for the current laser-ranging stations on average, which is considered to have resulted in a non-negligible systematic error in geodetic products. Numéro de notice : A2015-339 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-014-0776-y Date de publication en ligne : 13/11/2014 En ligne : https://doi.org/10.1007/s00190-014-0776-y Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=76708 [article]

Determination of precise satellite orbits and geodetic parameters using satellite laser ranging / Krzysztof Sosnica (2015)  

Public Titre : Determination of precise satellite orbits and geodetic parameters using satellite laser ranging Type de document : Rapport Auteurs : Krzysztof Sosnica, Auteur Editeur : Zurich : Schweizerischen Geodatischen Kommission / Commission Géodésique Suisse Année de publication : 2015 Collection : Geodätisch-Geophysikalische Arbeiten in der Schweiz, ISSN 0257-1722 num. 93 Importance : 257 p. Format : 21 x 30 cm ISBN/ISSN/EAN : 978-3-908440-38-3 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale [Termes IGN] Bernese [Termes IGN] données Ajisai [Termes IGN] données Lageos [Termes IGN] données Starlette [Termes IGN] données Stella [Termes IGN] géocentre [Termes IGN] Global Geodetic Observing System [Termes IGN] orbite basse [Termes IGN] perturbation orbitale [Termes IGN] repère de référence [Termes IGN] rotation de la Terre [Termes IGN] satellite de télémétrie [Termes IGN] télémétrie laser sur satellite Index. décimale : 30.63 Télémétrie laser sur satellite, Télémétrie laser sur lune, VLBI Résumé : (auteur) The contribution of the SLR to the definition of the origin of reference frame (geocenter coordinates), the global scale (in both the geometric and dynamic sense), and low degree coefficients of the Earth's gravity field (especially the oblateness term) is essential, due to the high stability of satellite orbits and the exceptional precision of SLR observations, which are affected only by few error sources. Moreover, the SLR technique has a great contribution to a definition of the global terrestrial reference frame, estimation of the Earth rotation parameters and the time variable Earth's gravity field. The long time series of precise SLR observations allow validating many models, e.g., ocean tide models, Earth gravity field models, atmospheric pressure loading models, atmosphere and ocean induced time variable gravity field models, etc. We have shown that appropriate modeling of gravitational and non-gravitational forces is essential for orbit determination of geodetic satellites. Concerning the gravitational forces, the coefficient C20 couses the largest perturbations on LAGEOS satellites. The sensitivity of LAGEOS orbits dramatically decreases for higher degree geopotential coefficients, whereas low orbiting geodetic satellites are very sensitive to both, low- and medium-degree coefficients of the Earth's gravity field. The differences between the current ocean tide models have bigger impact on LAGEOS orbits than the differences between the current Earth gravity field models. The mean differences between solutions using various ocean tide models (max. 1.32 mm of RMS) are larger than the mean differences between orbit solutions using various Earth gravity field models (max. 1.16 mm of RMS). Insufficient quality of the S2 tide constituent causes large variations of the empirical orbit parameters of SLR geodetic satellites, as well as variations for different type satellites, e.g., GRACE. The atmospheric drag causes a secular decay of semi-major axes of low orbiting geodetic satellites, i.e., Starlette, Stella, and AJISAI, whereas the Yarkovsky and the Yarkovsky- Schach effects cause a secular decay of LAGEOS-1 and LAGEOS-2. The decay of the semi-major axis of LAGEOS-1 is smaller than the decay reported in many earlier papers due to the satellite's de-spinning effect. The decay is fiaL1 = Note de contenu : 1 Introduction 1.1 Role of Satellite Laser Ranging in Science 1.2 Objectives and Methods 1.3 Structure 2 Satellite Geodesy 2.1 Reference Systems and Frames 2.2 Satellite Orbit Modeling 2.3 Parameter Estimation Using the Least-Squares Method 2.4 Global Navigation Satellite Systems (GNSS) 2.5 Satellite Laser Ranging 3 Gravitational Forces Acting on Geodetic Satellites 3.1 Solution Description 3.2 LAGEOS Sensitivity to Earth Gravity Field Models 3.3 LAGEOS Sensitivity to Ocean Tide Models 3.4 Discussion and Conclusions 4 Non-gravitational Forces Acting on Geodetic Satellites 4.1 Thermal effects 4.2 Earth Radiation Pressure 4.3 Atmospheric Drag 4.4 Discussion and Conclusions 5 Improving SLR Solutions 5.1 Impact of Loading Corrections on SLR Solutions 5.2 The Blue-Sky effect 5.3 Orbit Modeling of Low Orbiting Geodetic Satellites 5.4 Combined LAGEOS-LEO Solutions 5.5 Simultaneous Estimation of Gravity Field along with other Parameters 5.6 Time Variable Earth's Gravity Field From SLR 5.7 Discussion and Conclusions Numéro de notice : 14914 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Rapport de recherche DOI : sans En ligne : https://www.sgc.ethz.ch/sgc-volumes/sgk-93.pdf Format de la ressource électronique : URL Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=76821

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Laser ranging data analysis for a colocation campaign of French Transportable Laser Ranging System (FTLRS) in Tahiti / Xiaoni Wang in Journal of geodesy, vol 89 n° 1 (January 2015)  

Public [article]  inJournal of geodesy > vol 89 n° 1 (January 2015) . - pp 1 - 11 Titre : Laser ranging data analysis for a colocation campaign of French Transportable Laser Ranging System (FTLRS) in Tahiti Type de document : Article/Communication Auteurs : Xiaoni Wang, Auteur ; Pascal Bonnefond, Auteur ; Pierre Exertier, Auteur ; David Coulot , Auteur ; Richard Biancale, Auteur ; Jean-Michel Lemoine, Auteur ; Jean-Claude Poyard, Auteur ; Clément Courde, Auteur ; Jean-Pierre Barriot, Auteur ; François Barlier, Auteur Année de publication : 2015 Article en page(s) : pp 1 - 11 Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Systèmes de référence et réseaux [Termes IGN] analyse comparative [Termes IGN] co-positionnement [Termes IGN] données DORIS [Termes IGN] données GPS [Termes IGN] données Lageos [Termes IGN] données Starlette [Termes IGN] données TLS (télémétrie) [Termes IGN] International Terrestrial Reference Frame [Termes IGN] point de liaison (géodésie) [Termes IGN] Tahiti [Termes IGN] télémétrie laser transportable Résumé : (auteur) Tahiti is a unique geodetic site located in the south Pacific Ocean where few observatories exist nearby. The American mobile station MOBLAS-8 was installed in Tahiti in 1998, and GPS and DORIS systems were also deployed in its vicinity in order to develop this site into one of the fundamental colocated sites of the International Terrestrial Reference Frame. In order to make a new estimate of the colocation differences between the different techniques, a campaign of the French Transportable Laser Ranging System (FTLRS) was conducted in Tahiti between April and October 2011. The FTLRS was deployed close to the existing equipment. Observations for LAGEOS 1, LAGEOS 2 and Starlette were studied, and the solutions to the local ties between FTLRS, MOBLAS-8, DORIS and GPS were evaluated. Our results of the geodetic local-ties between laser stations and GPS agree well with the measurements made by the Institut National de l’Information Géographique et Forestière (IGN) during the campaign, with differences less than 2 mm in the vertical direction. The laser station range biases as a function of satellites are also presented, −3 (±2) mm for MOBLAS-8 and 3 (±3) mm for FTLRS, respectively. In addition, we investigated the role of time bias (ranging from a few hundreds of nanoseconds to one microsecond) given by the Time Transfer by Laser Link experiment, which shows a limited impact on the present SLR analysis. We also compared the coordinates of the three available techniques at Tahiti, i.e., laser, GPS and DORIS. We found the accuracy of laser solutions still needs to be improved, so that the SLR at Tahiti could contribute more effectively to the tracking of satellites and thus to the international reference frame. This study is useful in evaluating the SLR and other space techniques in order to prepare the deployment of new equipment in Tahiti in the near future. Numéro de notice : A2015-230 Affiliation des auteurs : IGN+Ext (2012-2019) Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-014-0755-3 En ligne : https://doi.org/10.1007/s00190-014-0755-3 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=76064 [article]