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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]

Three-Corner Hat for the assessment of the uncertainty of non-linear residuals of space-geodetic time series in the context of terrestrial reference frame analysis / Claudio Abbondanza in Journal of geodesy, vol 89 n° 4 (April 2015)  

Public [article]  inJournal of geodesy > vol 89 n° 4 (April 2015) . - pp 313-329 Titre : Three-Corner Hat for the assessment of the uncertainty of non-linear residuals of space-geodetic time series in the context of terrestrial reference frame analysis Type de document : Article/Communication Auteurs : Claudio Abbondanza, Auteur ; Zuheir Altamimi , Auteur ; T.M. Chin, Auteur ; Richard S. Gross, Auteur ; Michael B. Heflin, Auteur ; J. W. Parker, Auteur ; X. Wu, Auteur Année de publication : 2015 Article en page(s) : pp 313-329 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Systèmes de référence et réseaux [Termes IGN] co-positionnement [Termes IGN] corrélation temporelle [Termes IGN] estimation de cohérence [Termes IGN] hauteur ellipsoïdale [Termes IGN] incertitude de position [Termes IGN] International Terrestrial Reference Frame [Termes IGN] série temporelle [Termes IGN] signal GPS Résumé : (auteur) We discuss the application of the Three-Corner Hat (TCH) to time series of space-geodetic station position residuals with the purpose of characterizing the uncertainties of GPS, VLBI, SLR, DORIS for the International Terrestrial Reference Frame (ITRF) determination. Adopting simulations, we show that, in the absence of time-correlated errors, TCH is able to fully recover the nominal uncertainties of groups of observations whose intrinsic precisions are remarkably dissimilar to one another, as is the case for the space-geodetic techniques. When time-correlated errors are predominant, as it happens with GPS, TCH is affected by the increased variance of the observations and its estimates are positively biased. TCH applied to 16 ITRF co-located sites confirms that GPS, albeit affected by time-correlated errors, is the most precise of the space-geodetic techniques. GPS median uncertainties are 1.1, 1.2 and 2.8 mm, for the north, east and height component, respectively. VLBI performs particularly well in the horizontal component, the median uncertainties being ≈2 mm. The height component is ∼3 times larger than the GPS one. SLR and DORIS median uncertainties exceed by far the 7 mm level on all of the three components. Comparing TCH results with station position repeatabilities, we find that the two metrics are in striking agreement for VLBI and DORIS, but not for SLR and GPS. The inconsistencies between TCH and station repeatabilities for co-located GPS and SLR point to the presence of either specific station-dependent biases or low-quality co-locations. Scaling factors derived adopting the ratio between TCH and median formal errors on the positions suggest the station position covariances have to be up-scaled for VLBI, SLR, DORIS and down-scaled for GPS. Numéro de notice : A2015-340 Affiliation des auteurs : LASTIG LAREG+Ext (2012-mi2018) Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-014-0777-x Date de publication en ligne : 18/11/2014 En ligne : https://doi.org/10.1007/s00190-014-0777-x Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=76709 [article]

SHPTS: towards a new method for generating precise global ionospheric TEC map based on spherical harmonic and generalized trigonometric series functions / Zishen Li in Journal of geodesy, vol 89 n° 4 (April 2015)  

Public [article]  inJournal of geodesy > vol 89 n° 4 (April 2015) . - pp 333 - 345 Titre : SHPTS: towards a new method for generating precise global ionospheric TEC map based on spherical harmonic and generalized trigonometric series functions Type de document : Article/Communication Auteurs : Zishen Li, Auteur ; Yunbin Yuan, Auteur ; Ningbo Wang, Auteur ; et al., Auteur Année de publication : 2015 Article en page(s) : pp 333 - 345 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale [Termes IGN] données DORIS [Termes IGN] données Topex-Poseidon [Termes IGN] fonction harmonique [Termes IGN] harmonique sphérique [Termes IGN] modèle ionosphérique [Termes IGN] série de Fourier [Termes IGN] signal GNSS [Termes IGN] teneur totale en électrons [Termes IGN] trigonométrie sphérique Résumé : (auteur) To take maximum advantage of the increasing Global Navigation Satellite Systems (GNSS) data to improve the accuracy and resolution of global ionospheric TEC map (GIM), an approach, named Spherical Harmonic plus generalized Trigonometric Series functions (SHPTS), is proposed by integrating the spherical harmonic and the generalized trigonometric series functions on global and local scales, respectively. The SHPTS-based GIM from January 1st, 2001 to December 31st, 2011 (about one solar cycle) is validated by the ionospheric TEC from raw global GPS data, the GIM released by the current Ionospheric Associate Analysis Center (IAAC), the TOPEX/Poseidon satellite and the DORIS. The present results show that the SHPTS-based GIM over the area where no real data are available has the same accuracy level (approximately 2–6 TECu) to that released by the current IAAC. However, the ionospheric TEC in the SHPTS-based GIM over the area covered by real data is more accurate (approximately 1.5 TECu) than that of the GIM (approximately 3.0 TECu) released by the current IAAC. The external accuracy of the SHPTS-based GIM validated by the TOPEX/Poseidon and DORIS is approximately 2.5–5.5 and 1.5–4.5 TECu, respectively. In particular, the SHPTS-based GIM is the best or almost the best ranked, along with those of JPL and UPC, when they are compared with TOPEX/Poseidon measurements, and the best (in addition to UPC) when they are validated with DORIS data. With the increase in the number of GNSS satellites and contributing stations, the performance of the SHPTS-based GIM can be further improved. The SHPTS-based GIM routinely calculated using global GPS, GLONASS and BDS data will be found at the website http://​www.​gipp.​org.​cn. Numéro de notice : A2015-341 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-014-0778-9 Date de publication en ligne : 02/12/2014 En ligne : https://doi.org/10.1007/s00190-014-0778-9 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=76710 [article]

Regional vertical total electron content (VTEC) modeling together with satellite and receiver differential code biases (DCBs) using semi-parametric multivariate adaptive regression B-splines (SP-BMARS) / Murat Durmaz in Journal of geodesy, vol 89 n° 4 (April 2015)  

Public [article]  inJournal of geodesy > vol 89 n° 4 (April 2015) . - pp 347 - 360 Titre : Regional vertical total electron content (VTEC) modeling together with satellite and receiver differential code biases (DCBs) using semi-parametric multivariate adaptive regression B-splines (SP-BMARS) Type de document : Article/Communication Auteurs : Murat Durmaz, Auteur ; Mahmut Onur Karslioglu, Auteur Année de publication : 2015 Article en page(s) : pp 347 - 360 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale [Termes IGN] analyse comparative [Termes IGN] B-Spline [Termes IGN] erreur systématique [Termes IGN] harmonique sphérique [Termes IGN] modèle ionosphérique [Termes IGN] régression multiple [Termes IGN] teneur totale en électrons [Termes IGN] teneur verticale totale en électrons Résumé : (auteur) There are various global and regional methods that have been proposed for the modeling of ionospheric vertical total electron content (VTEC). Global distribution of VTEC is usually modeled by spherical harmonic expansions, while tensor products of compactly supported univariate B-splines can be used for regional modeling. In these empirical parametric models, the coefficients of the basis functions as well as differential code biases (DCBs) of satellites and receivers can be treated as unknown parameters which can be estimated from geometry-free linear combinations of global positioning system observables. In this work we propose a new semi-parametric multivariate adaptive regression B-splines (SP-BMARS) method for the regional modeling of VTEC together with satellite and receiver DCBs, where the parametric part of the model is related to the DCBs as fixed parameters and the non-parametric part adaptively models the spatio-temporal distribution of VTEC. The latter is based on multivariate adaptive regression B-splines which is a non-parametric modeling technique making use of compactly supported B-spline basis functions that are generated from the observations automatically. This algorithm takes advantage of an adaptive scale-by-scale model building strategy that searches for best-fitting B-splines to the data at each scale. The VTEC maps generated from the proposed method are compared numerically and visually with the global ionosphere maps (GIMs) which are provided by the Center for Orbit Determination in Europe (CODE). The VTEC values from SP-BMARS and CODE GIMs are also compared with VTEC values obtained through calibration using local ionospheric model. The estimated satellite and receiver DCBs from the SP-BMARS model are compared with the CODE distributed DCBs. The results show that the SP-BMARS algorithm can be used to estimate satellite and receiver DCBs while adaptively and flexibly modeling the daily regional VTEC. Numéro de notice : A2015-342 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-014-0779-8 Date de publication en ligne : 23/11/2014 En ligne : https://doi.org/10.1007/s00190-014-0779-8 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=76712 [article]

Separation of atmospheric, oceanic and hydrological polar motion excitation mechanisms based on a combination of geometric and gravimetric space observations / F. Göttl in Journal of geodesy, vol 89 n° 4 (April 2015)  

Public [article]  inJournal of geodesy > vol 89 n° 4 (April 2015) . - pp 377 - 390 Titre : Separation of atmospheric, oceanic and hydrological polar motion excitation mechanisms based on a combination of geometric and gravimetric space observations Type de document : Article/Communication Auteurs : F. Göttl, Auteur ; M. Schmidt, Auteur ; Florian Seitz, Auteur ; Mathis Blossfeld, Auteur Année de publication : 2015 Article en page(s) : pp 377 - 390 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale [Termes IGN] atmosphère terrestre [Termes IGN] champ de pesanteur terrestre [Termes IGN] géodésie physique [Termes IGN] masse d'eau [Termes IGN] mouvement du pôle [Termes IGN] océanographie spatiale [Termes IGN] réseau de surveillance géophysique [Termes IGN] rotation de la Terre Résumé : (auteur) The goal of our study is to determine accurate time series of geophysical Earth rotation excitations to learn more about global dynamic processes in the Earth system. For this purpose, we developed an adjustment model which allows to combine precise observations from space geodetic observation systems, such as Satellite Laser Ranging (SLR), Global Navigation Satellite Systems, Very Long Baseline Interferometry, Doppler Orbit determination and Radiopositioning Integrated on Satellite, satellite altimetry and satellite gravimetry in order to separate geophysical excitation mechanisms of Earth rotation. Three polar motion time series are applied to derive the polar motion excitation functions (integral effect). Furthermore we use five time variable gravity field solutions from Gravity Recovery and Climate Experiment to determine not only the integral mass effect but also the oceanic and hydrological mass effects by applying suitable filter techniques and a land–ocean mask. For comparison the integral mass effect is also derived from degree 2 potential coefficients that are estimated from SLR observations. The oceanic mass effect is also determined from sea level anomalies observed by satellite altimetry by reducing the steric sea level anomalies derived from temperature and salinity fields of the oceans. Due to the combination of all geodetic estimated excitations the weaknesses of the individual processing strategies can be reduced and the technique-specific strengths can be accounted for. The formal errors of the adjusted geodetic solutions are smaller than the RMS differences of the geophysical model solutions. The improved excitation time series can be used to improve the geophysical modeling. Numéro de notice : A2015-343 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-014-0782-0 Date de publication en ligne : 18/12/2014 En ligne : https://doi.org/10.1007/s00190-014-0782-0 Format de la ressource électronique : URL Article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=76715 [article]

An alternative ionospheric correction model for global navigation satellite systems / M.M. Hoque in Journal of geodesy, vol 89 n° 4 (April 2015)  

Public [article]  inJournal of geodesy > vol 89 n° 4 (April 2015) . - pp 391 - 406 Titre : An alternative ionospheric correction model for global navigation satellite systems Type de document : Article/Communication Auteurs : M.M. Hoque, Auteur ; Norbert Jakowski, Auteur Année de publication : 2015 Article en page(s) : pp 391 - 406 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale [Termes IGN] correction ionosphérique [Termes IGN] ionosphère [Termes IGN] modèle ionosphérique [Termes IGN] propagation ionosphérique Résumé : (auteur) The ionosphere is recognized as a major error source for single-frequency operations of global navigation satellite systems (GNSS). To enhance single-frequency operations the global positioning system (GPS) uses an ionospheric correction algorithm (ICA) driven by 8 coefficients broadcasted in the navigation message every 24 h. Similarly, the global navigation satellite system Galileo uses the electron density NeQuick model for ionospheric correction. The Galileo satellite vehicles (SVs) transmit 3 ionospheric correction coefficients as driver parameters of the NeQuick model. In the present work, we propose an alternative ionospheric correction algorithm called Neustrelitz TEC broadcast model NTCM-BC that is also applicable for global satellite navigation systems. Like the GPS ICA or Galileo NeQuick, the NTCM-BC can be optimized on a daily basis by utilizing GNSS data obtained at the previous day at monitor stations. To drive the NTCM-BC, 9 ionospheric correction coefficients need to be uploaded to the SVs for broadcasting in the navigation message. Our investigation using GPS data of about 200 worldwide ground stations shows that the 24-h-ahead prediction performance of the NTCM-BC is better than the GPS ICA and comparable to the Galileo NeQuick model. We have found that the 95 percentiles of the prediction error are about 16.1, 16.1 and 13.4 TECU for the GPS ICA, Galileo NeQuick and NTCM-BC, respectively, during a selected quiet ionospheric period, whereas the corresponding numbers are found about 40.5, 28.2 and 26.5 TECU during a selected geomagnetic perturbed period. However, in terms of complexity the NTCM-BC is easier to handle than the Galileo NeQuick and in this respect comparable to the GPS ICA. Numéro de notice : A2015-344 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-014-0783-z Date de publication en ligne : 13/12/2014 En ligne : https://doi.org/10.1007/s00190-014-0783-z Format de la ressource électronique : URL Article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=76716 [article]