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Intersatellite laser ranging instrument for the GRACE follow-on mission / B. Sheard in Journal of geodesy, vol 86 n° 12 (December 2012)  

Public [article]  inJournal of geodesy > vol 86 n° 12 (December 2012) . - pp 1083 - 1095 Titre : Intersatellite laser ranging instrument for the GRACE follow-on mission Type de document : Article/Communication Auteurs : B. Sheard, Auteur ; Gerhard Heinzel, Auteur ; K. Danzmann, Auteur ; et al., Auteur Année de publication : 2012 Article en page(s) : pp 1083 - 1095 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique [Termes IGN] GRACE [Termes IGN] mission spatiale [Termes IGN] poursuite de satellite [Termes IGN] surveillance Résumé : (Auteur) The Gravity Recovery and Climate Experiment (GRACE) has demonstrated that low–low satellite-to-satellite tracking enables monitoring the time variations of the Earth’s gravity field on a global scale, in particular those caused by mass-transport within the hydrosphere. Due to the importance of long-term continued monitoring of the variations of the Earth’s gravitational field and the limited lifetime of GRACE, a follow-on mission is currently planned to be launched in 2017. In order to minimise risk and the time to launch, the follow-on mission will be basically a rebuild of GRACE with microwave ranging as the primary instrument for measuring changes of the intersatellite distance. Laser interferometry has been proposed as a method to achieve improved ranging precision for future GRACE-like missions and is therefore foreseen to be included as demonstrator experiment in the follow-on mission now under development. This paper presents the top-level architecture of an interferometric laser ranging system designed to demonstrate the technology which can also operate in parallel with the microwave ranging system of the GRACE follow-on mission. Numéro de notice : A2012-649 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-012-0566-3 Date de publication en ligne : 08/05/2012 En ligne : https://doi.org/10.1007/s00190-012-0566-3 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=32095 [article]

Exemplaires(1)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
266-2012121	RAB	Revue	Centre de documentation	En réserve L003	Disponible

The 2008 DGFI realization of the ITRS: DTRF2008 / Manuela Seitz in Journal of geodesy, vol 86 n° 12 (December 2012)  

Public [article]  inJournal of geodesy > vol 86 n° 12 (December 2012) . - pp 1097 - 1123 Titre : The 2008 DGFI realization of the ITRS: DTRF2008 Type de document : Article/Communication Auteurs : Manuela Seitz, Auteur ; Detlef Angermann, Auteur ; et al., Auteur Année de publication : 2012 Article en page(s) : pp 1097 - 1123 Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Systèmes de référence et réseaux [Termes IGN] Institut national de l'information géographique et forestière (France) [Termes IGN] International Terrestrial Reference Frame [Termes IGN] International Terrestrial Reference System [Termes IGN] station permanente [Termes IGN] système de positionnement par satellites Résumé : (Auteur) A new realization of the International Terrestrial System was computed at the ITRS Combination Centre at DGFI as a contribution to ITRF2008. The solution is labelled DTRF2008. In the same way as in the DGFI computation for ITRF2005 it is based on either normal equation systems or estimated parameters derived from VLBI, SLR, GPS and DORIS observations by weekly or session-wise processing. The parameter space of the ITRS realization comprises station positions and velocities and daily resolved Earth Orientation Parameters (EOP), whereby for the first time also nutation parameters are included. The advantage of starting from time series of input data is that the temporal behaviour of geophysical parameters can be investigated to decide whether the parameters can contribute to the datum realization of the ITRF. In the same way, a standardized analysis of station position time series can be performed to detect and remove discontinuities. The advantage of including EOP in the ITRS realization is twofold: (1) the combination of the coordinates of the terrestrial pole—estimated from all contributing techniques—links the technique networks in two components of the orientation, leading to an improvement of consistency of the Terrestrial Reference Frame (TRF) and (2) in their capacity as parameters common to all techniques, the terrestrial pole coordinates enhance the selection of local ties as they provide a measure for the consistency of the combined frame. The computation strategy of DGFI is based on the combination of normal equation systems while at the ITRS Combination Centre at IGN solutions are combined. The two independent ITRS realizations provide the possibility to assess the accuracy of ITRF by comparison of the two frames. The accuracy evaluation was done separately for the datum parameters (origin, orientation and scale) and the network geometry. The accuracy of the datum parameters, assessed from the comparison of DTRF2008 and ITRF2008, is between 2–5 mm and 0.1–0.8 mm/year depending on the technique. The network geometry (station positions and velocities) agrees within 3.2 mm and 1.0 mm/year. A comparison of DTRF2008 and ITRF2005 provides similar results for the datum parameters, but there are larger differences for the network geometry. The internal accuracy of DTRF2008—that means the level of conservation of datum information and network geometry within the combination—was derived from comparisons with the technique-only multi-year solutions. From this an internal accuracy of 0.32 mm for the VLBI up to 3.3 mm for the DORIS part of the network is found. The internal accuracy of velocities ranges from 0.05 mm/year for VLBI to 0.83 mm/year for DORIS. The internal consistency of DTRF2008 for orientation can be derived from the analysis of the terrestrial pole coordinates. It is estimated at 1.5–2.5 mm for the GPS, VLBI and SLR parts of the network. The consistency of these three and the DORIS network part is within 6.5 mm. Numéro de notice : A2012-650 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-012-0567-2 Date de publication en ligne : 04/05/2012 En ligne : https://doi.org/10.1007/s00190-012-0567-2 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=32096 [article]

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Code-barres	Cote	Support	Localisation	Section	Disponibilité
266-2012121	RAB	Revue	Centre de documentation	En réserve L003	Disponible

High-frequency signal and noise estimates of CSR GRACE RL04 / J.A. Bonin in Journal of geodesy, vol 86 n° 12 (December 2012)  

Public [article]  inJournal of geodesy > vol 86 n° 12 (December 2012) . - pp 1165 - 1177 Titre : High-frequency signal and noise estimates of CSR GRACE RL04 Type de document : Article/Communication Auteurs : J.A. Bonin, Auteur ; S. Bettadpur, Auteur ; B. Tapley, Auteur Année de publication : 2012 Article en page(s) : pp 1165 - 1177 Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique [Termes IGN] bruit (théorie du signal) [Termes IGN] données GRACE [Termes IGN] erreur [Termes IGN] filtrage du bruit [Termes IGN] force de gravitation [Termes IGN] levé gravimétrique [Termes IGN] rapport signal sur bruit [Termes IGN] traitement du signal Résumé : (Auteur) A sliding window technique is used to create daily-sampled Gravity Recovery and Climate Experiment (GRACE) solutions with the same background processing as the official CSR RL04 monthly series. By estimating over shorter time spans, more frequent solutions are made using uncorrelated data, allowing for higher frequency resolution in addition to daily sampling. Using these data sets, high-frequency GRACE errors are computed using two different techniques: assuming the GRACE high-frequency signal in a quiet area of the ocean is the true error, and computing the variance of differences between multiple high-frequency GRACE series from different centers. While the signal-to-noise ratios prove to be sufficiently high for confidence at annual and lower frequencies, at frequencies above 3 cycles/year the signal-to-noise ratios in the large hydrological basins looked at here are near 1.0. Comparisons with the GLDAS hydrological model and high frequency GRACE series developed at other centers confirm CSR GRACE RL04’s poor ability to accurately and reliably measure hydrological signal above 3–9 cycles/year, due to the low power of the large-scale hydrological signal typical at those frequencies compared to the GRACE errors. Numéro de notice : A2012-651 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-012-0572-5 Date de publication en ligne : 03/06/2012 En ligne : https://doi.org/10.1007/s00190-012-0572-5 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=32097 [article]

Exemplaires(1)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
266-2012121	RAB	Revue	Centre de documentation	En réserve L003	Disponible