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Auteur Pierguido Sarti |
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Affiner la recherche Interroger des sources externesGlobal geodetic observatories / Claude Boucher in Advances in space research, vol 55 n° 1 ([01/01/2015])
Titre : Global geodetic observatories Type de document : Article/Communication Auteurs : Claude Boucher Année de publication : 2015 Article en page(s) : pp 24 - 39 Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale
[Termes IGN] co-positionnement
[Termes IGN] Global Geodetic Observing System
[Termes IGN] International Terrestrial Reference Frame
[Termes IGN] point de liaison (géodésie)Résumé : (auteur) Global geodetic observatories (GGO) play an increasingly important role both for scientific and societal applications, in particular for the maintenance and evolution of the reference frame and those applications that rely on the reference frame for their viability. The International Association of Geodesy (IAG), through the Global Geodetic Observing System (GGOS), is fully involved in coordinating the development of these systems and ensuring their quality, perenniality and accessibility. This paper reviews the current role, basic concepts, and some of the critical issues associated with the GGOs, and advocates for their expansion to enhance co-location with other observing techniques (gravity, meteorology, etc). The historical perspective starts with the MERIT campaign, followed by the creation of international services (IERS, IGS, ILRS, IVS, IDS, etc). It provides a basic definition of observing systems and observatories and the build up of the international networks and the role of co-locations in geodesy and geosciences and multi-technique processing and data products. This paper gives special attention to the critical topic of local surveys and tie vectors among co-located systems in sites; the agreement of space geodetic solutions and the tie vectors now place one of the most significant limitations on the quality of integrated data products, most notably the ITRF. This topic focuses on survey techniques, extrapolation to instrument reference points, computation techniques, systematic biases, and alignment of the individual technique reference frames into ITRF. The paper also discusses the design, layout and implementation of network infrastructure, including the role of GGOS and the benefit that would be achieved with better standardization and international governance. Numéro de notice : A2015-295 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.asr.2014.10.011 En ligne : https://doi.org/10.1016/j.asr.2014.10.011 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=76455
in Advances in space research > vol 55 n° 1 [01/01/2015] . - pp 24 - 39[article]
contenu dans Reference frames for applications in geosciences, Proceedings of IAG Symposium REFAG 2010 / Zuheir Altamimi (2013)
Titre : Local ties and co-location sites : Some considerations after the release of ITRF2 Type de document : Article/Communication Auteurs : Pierguido Sarti, Auteur ; Claudio Abbondanza, Auteur ; Zuheir Altamimi Editeur : Berlin, Heidelberg, Vienne, New York, ... : Springer Année de publication : 2013 Collection : International Association of Geodesy Symposia, ISSN 0939-9585 num. 138 Conférence : REFAG 2010, Reference Frames for Applications in Geosciences, IAG symposium 04/10/2010 08/10/2010 Champs-sur-Marne France Proceedings Springer Importance : pp 75 - 80 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Systèmes de référence et réseaux
[Termes IGN] International Terrestrial Reference Frame
[Termes IGN] point de liaison (géodésie)
[Termes IGN] résiduRésumé : (Auteur) Tie vectors (TVs) measured at co-location sites carry fundamental information for the computation of the International Terrestrial Reference Frame (ITRF). The combination of the different frames stemming from each space geodetic (SG) technique relies on the availability and accuracy of the relative positions between reference points of co-located SG instruments, i.e. TV. If, on the one hand, TVs accurate at 1 mm level are sought to preserve the accuracy of the global frame and fulfill the requirements of the global geodetic observing system (GGOS), on the other hand, the assessment of TVs accuracy is not easy. Their accuracies are often questioned on the base of their agreement within the combination of SG solutions and the combination residuals. Though, the final discrepancies highlighted by the combination residuals do not depend uniquely on the accuracy of the TVs but are influenced by several factors of different origin. In this paper, we identify some of these factors and investigate their possible origin adopting different perspectives: local ties and terrestrial surveying, SG techniques and frames combination. Our purpose is to highlight some of the possible systematic errors in terrestrial and SG data analysis as well as to identify actions to be taken in the near future to mitigate the biases highlighted by the residuals of the combination. In contrast to what is commonly assumed, we show that the residuals are potentially influenced by a combination of biases affecting the TVs, their alignment and the SG solutions. Therefore, an objective evaluation of the error sources is necessary for each SG technique in order to improve their results as well as the combined SG products. Numéro de notice : C2010-014 Affiliation des auteurs : LAREG+Ext (1991-2011) Thématique : POSITIONNEMENT Nature : Communication nature-HAL : ComAvecCL&ActesPubliésIntl DOI : 10.1007/978-3-642-32998-2_13 Date de publication en ligne : 27/11/2012 En ligne : https://doi.org/10.1007/978-3-642-32998-2_13 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=65069
Titre : Local effects of redundant terrestrial and GPS-based tie vectors in ITRF-like combinations Type de document : Article/Communication Auteurs : Claudio Abbondanza, Auteur ; Zuheir Altamimi Année de publication : 2009 Article en page(s) : pp 1031 - 1040 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Systèmes de référence et réseaux
[Termes IGN] analyse comparative
[Termes IGN] géodésie terrestre
[Termes IGN] interférométrie à très grande base
[Termes IGN] International Terrestrial Reference Frame
[Termes IGN] point de liaison (géodésie)
[Termes IGN] positionnement par GPS
[Termes IGN] système de référence mondialRésumé : (Auteur) Tie vectors (TVs) between co-located space geodetic instruments are essential for combining terrestrial reference frames (TRFs) realised using different techniques. They provide relative positioning between instrumental reference points (RPs) which are part of a global geodetic network such as the international terrestrial reference frame (ITRF). This paper gathers the set of very long baseline interferometry (VLBI)–global positioning system (GPS) local ties performed at the observatory of Medicina (Northern Italy) during the years 2001–2006 and discusses some important aspects related to the usage of co-location ties in the combinations of TRFs. Two measurement approaches of local survey are considered here: a GPS-based approach and a classical approach based on terrestrial observations (i.e. angles, distances and height differences). The behaviour of terrestrial local ties, which routinely join combinations of space geodetic solutions, is compared to that of GPS-based local ties. In particular, we have performed and analysed different combinations of satellite laser ranging (SLR), VLBI and GPS long term solutions in order to (i) evaluate the local effects of the insertion of the series of TVs computed at Medicina, (ii) investigate the consistency of GPS-based TVs with respect to space geodetic solutions, (iii) discuss the effects of an imprecise alignment of TVs from a local to a global reference frame. Results of ITRF-like combinations show that terrestrial TVs originate the smallest residuals in all the three components. In most cases, GPS-based TVs fit space geodetic solutions very well, especially in the horizontal components (N, E). On the contrary, the estimation of the VLBI RP Up component through GPS technique appears to be awkward, since the corresponding post fit residuals are considerably larger. Besides, combination tests including multi-temporal TVs display local effects of residual redistribution, when compared to those solutions where Medicina TVs are added one at a time. Finally, the combination of TRFs turns out to be sensitive to the orientation of the local tie into the global frame. Copyright Springer Numéro de notice : A2009-476 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-009-0321-6 En ligne : https://doi.org/10.1007/s00190-009-0321-6 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=30105
in Journal of geodesy > vol 83 n° 11 (November 2009) . - pp 1031 - 1040[article]Exemplaires(1)
Code-barres Cote Support Localisation Section Disponibilité 266-09101 SL Revue Centre de documentation Revues en salle Disponible
Titre : Local effects of redundant terrestrial and GPS-based tie vectors in ITRF-like combinations Type de document : Article/Communication Auteurs : Claudio Abbondanza, Auteur ; Zuheir Altamimi Année de publication : 2009 Article en page(s) : pp 1031 - 1040 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Systèmes de référence et réseaux
[Termes IGN] co-positionnement
[Termes IGN] interférométrie à très grande base
[Termes IGN] International Terrestrial Reference Frame
[Termes IGN] point de liaison (géodésie)
[Termes IGN] positionnement par GPSRésumé : (auteur) Tie vectors (TVs) between co-located space geodetic instruments are essential for combining terrestrial reference frames (TRFs) realised using different techniques. They provide relative positioning between instrumental reference points (RPs) which are part of a global geodetic network such as the international terrestrial reference frame (ITRF). This paper gathers the set of very long baseline interferometry (VLBI)–global positioning system (GPS) local ties performed at the observatory of Medicina (Northern Italy) during the years 2001–2006 and discusses some important aspects related to the usage of co-location ties in the combinations of TRFs. Two measurement approaches of local survey are considered here: a GPS-based approach and a classical approach based on terrestrial observations (i.e. angles, distances and height differences). The behaviour of terrestrial local ties, which routinely join combinations of space geodetic solutions, is compared to that of GPS-based local ties. In particular, we have performed and analysed different combinations of satellite laser ranging (SLR), VLBI and GPS long term solutions in order to (i) evaluate the local effects of the insertion of the series of TVs computed at Medicina, (ii) investigate the consistency of GPS-based TVs with respect to space geodetic solutions, (iii) discuss the effects of an imprecise alignment of TVs from a local to a global reference frame. Results of ITRF-like combinations show that terrestrial TVs originate the smallest residuals in all the three components. In most cases, GPS-based TVs fit space geodetic solutions very well, especially in the horizontal components (N, E). On the contrary, the estimation of the VLBI RP Up component through GPS technique appears to be awkward, since the corresponding post fit residuals are considerably larger. Besides, combination tests including multi-temporal TVs display local effects of residual redistribution, when compared to those solutions where Medicina TVs are added one at a time. Finally, the combination of TRFs turns out to be sensitive to the orientation of the local tie into the global frame. Numéro de notice : A2009-583 Affiliation des auteurs : IGN+Ext (1940-2011) Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-009-0321-6 En ligne : https://doi.org/10.1007/s00190-009-0321-6 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=88652
in Journal of geodesy > vol 83 n° 11 (November 2009) . - pp 1031 - 1040[article]Exemplaires(1)
Code-barres Cote Support Localisation Section Disponibilité 266-09101 SL Revue Centre de documentation Revues en salle Disponible
Titre : Indirect approach to invariant point determination for SLR and VLBI systems: an assessment Type de document : Article/Communication Auteurs : John Dawson, Auteur ; Pierguido Sarti, Auteur ; G.M. Johnston, Auteur ; et al., Auteur Année de publication : 2007 Article en page(s) : pp 433 - 441 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale
[Termes IGN] erreur systématique
[Termes IGN] interférométrie à très grande base
[Termes IGN] invariant
[Termes IGN] point de liaison (géodésie)
[Termes IGN] télémétrie laser sur satelliteRésumé : (Auteur) We assess the accuracy of some indirect approaches to invariant point (IVP), or system reference point, determination of satellite laser ranging (SLR) and very long baseline interferometry (VLBI) systems using both observed and simulated survey data sets. Indirect IVP determination involves the observation of targets located on these systems during specific rotational sequences and by application of geometrical models that describe the target motion during these sequences. Of concern is that most SLR and VLBI systems have limited rotational freedom thereby placing constraint on the reliability of parameter estimation, including the IVP position. We assess two current approaches to IVP analysis using survey data observed at the Yarragadee (Australia) SLR and the Medicina (Italy) VLBI sites and also simulated data of a large rotationally constrained (azimuth-elevation) VLBI system. To improve reliability we introduce and assess some new geometric conditions, including inter-axis, inter-circle and inter-target conditions, to existing IVP analysis strategies. The error component of a local tie specifically associated with the indirect determination of SLR and VLBI IVP is less than 0.5 mm. For systems with significant rotational limits we find that the inter-axis and inter-circle conditions are critical to the computation of unbiased IVP coordinates at the sub-millimetre level. When the inter-axis and inter-circle geometric conditions are not imposed, we retrieve biased vertical coordinates of the IVP (in our simulated VLBI system) in the range of 1.2–3.4 mm. Using the new geometric conditions we also find that the axis-offset estimates can be recovered at the sub- millimetre accuracy (0.5 mm). Copyright Springer Numéro de notice : A2007-241 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-006-0125-x En ligne : https://doi.org/10.1007/s00190-006-0125-x Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=28604
in Journal of geodesy > vol 81 n° 6-8 (June - August 2007) . - pp 433 - 441[article]Exemplaires(2)
Code-barres Cote Support Localisation Section Disponibilité 266-07062 RAB Revue Centre de documentation En réserve L003 Disponible 266-07061 RAB Revue Centre de documentation En réserve L003 Disponible Permalink
