Centre dedocumentation
scientifique

Dépouillements

Geocenter variations derived from GPS tracking of the GRACE satellites / Z. Kang in Journal of geodesy, vol 83 n° 10 (October 2009)  

Public [article]  inJournal of geodesy > vol 83 n° 10 (October 2009) . - pp 895 - 901 Titre : Geocenter variations derived from GPS tracking of the GRACE satellites Type de document : Article/Communication Auteurs : Z. Kang, Auteur ; B. Tapley, Auteur ; J. Chen, Auteur ; John Ries, Auteur ; S. Bettadpur, Auteur Année de publication : 2009 Article en page(s) : pp 895 - 901 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique [Termes IGN] géocentre [Termes IGN] GRACE [Termes IGN] orbite basse [Termes IGN] orbitographie par GNSS [Termes IGN] poursuite de satellite Résumé : (Auteur) Two 4.5-year sets of daily geocenter variations have been derived from GPS-LEO (Low-Earth Orbiter) tracking of the GRACE (Gravity Recovery And Climate Experiment) satellites. The twin GRACE satellites, launched in March 2002, are each equipped with a BlackJack global positioning system (GPS) receiver for precise orbit determination and gravity recovery. Since launch, there have been significant improvements in the background force models used for satellite orbit determination, most notably the model for the geopotential, which has resulted in significant improvements to the orbit determination accuracy. The purpose of this paper is to investigate the potential for determining seasonal (annual and semiannual) geocenter variations using GPS-LEO tracking data from the GRACE twin satellites. Internal comparison between the GRACE-A and GRACE-B derived geocenter variations shows good agreement. In addition, the annual and semiannual variations of geocenter motions determined from this study have been compared with other space geodetic solutions and predictions from geophysical models. The comparisons show good agreement except for the phase of the z-translation component. Copyright Springer Numéro de notice : A2009-428 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-009-0307-4 En ligne : https://doi.org/10.1007/s00190-009-0307-4 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=30059 [article]

Réservation

Réserver ce document

Exemplaires (1)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
266-09091	SL	Revue	Centre de documentation	Revues en salle	Disponible

Recursive algorithms for the computation of the potential harmonic coefficients of a constant density polyhedron / Dimitrios Tsoulis in Journal of geodesy, vol 83 n° 10 (October 2009)  

Public [article]  inJournal of geodesy > vol 83 n° 10 (October 2009) . - pp 925 - 942 Titre : Recursive algorithms for the computation of the potential harmonic coefficients of a constant density polyhedron Type de document : Article/Communication Auteurs : Dimitrios Tsoulis, Auteur ; Olivier Jamet , Auteur ; Jérome Verdun , Auteur ; Nicolas Gonindard, Auteur Année de publication : 2009 Projets : 3-projet - voir note / Article en page(s) : pp 925 - 942 Note générale : Bibliographie The present research has been carried out in the frame of France-Greek bilateral cooperation PHC Platon, project number 15063 VE. Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique [Termes IGN] harmonique sphérique [Termes IGN] polyèdre [Termes IGN] potentiel de pesanteur terrestre Résumé : (Auteur) The gravitational potential of a constant density general polyhedron can be expressed both in terms of a closed analytical expression and as a series expansion involving the corresponding spherical harmonic coefficients. The latter can be obtained from two independent algorithms, which differ not only in their algorithmic architecture but in their efficiency and overall performance, especially when computing the coefficients of higher degree and order. In the present paper a comparative study of all these three approaches is carried out focusing on the numerical implementation of the recursive relations appearing in the two algorithms for the computation of the polyhedral potential harmonic coefficients. The performed numerical investigations show that the linear algorithm proposed by Jamet and Thomas (Proceedings of the second international GOCE user workshop, ‘GOCE, The Geoid and Oceanography’, ESA-ESRIN, Frascati, Italy, 8–10 March 2004, ESA SP-569, 2004), but so far not implemented, achieves a reasonable accuracy at a computational expense that opens to practical applications, for instance in the field of satellite gravimetry/gradiometry interpretation. The convergence behavior of the linear recursion algorithm is studied thoroughly and a computational procedure is proposed that enables the stable computation of potential harmonic coefficients up to degree 60 when referring to an arbitrarily shaped polyhedral body. Numéro de notice : A2009-429 Affiliation des auteurs : LAREG+Ext (1991-2011) Autre URL associée : vers HAL Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-009-0310-9 Date de publication en ligne : 10/03/2009 En ligne : http://dx.doi.org/10.1007/s00190-009-0310-9 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=30060 [article]

Réservation

Réserver ce document

Exemplaires (1)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
266-09091	SL	Revue	Centre de documentation	Revues en salle	Disponible

Improving the GNSS positioning stochastic model in the presence of ionospheric scintillation / M. Aquino in Journal of geodesy, vol 83 n° 10 (October 2009)  

Public [article]  inJournal of geodesy > vol 83 n° 10 (October 2009) . - pp 953 - 966 Titre : Improving the GNSS positioning stochastic model in the presence of ionospheric scintillation Type de document : Article/Communication Auteurs : M. Aquino, Auteur ; João F.G. Monico, Auteur ; A.H. Dodson, Auteur ; et al., Auteur Année de publication : 2009 Article en page(s) : pp 953 - 966 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale [Termes IGN] modèle stochastique [Termes IGN] positionnement par GNSS [Termes IGN] propagation ionosphérique [Termes IGN] récepteur GNSS [Termes IGN] scintillation [Termes IGN] teneur totale en électrons Résumé : (Auteur) Ionospheric scintillations are caused by time- varying electron density irregularities in the ionosphere, occurring more often at equatorial and high latitudes. This paper focuses exclusively on experiments undertaken in Europe, at geographic latitudes between ~50°N and ~80°N, where a network of GPS receivers capable of monitoring Total Electron Content and ionospheric scintillation parameters was deployed. The widely used ionospheric scintillation indices S4 and {\sigma_{\varphi}} represent a practical measure of the intensity of amplitude and phase scintillation affecting GNSS receivers. However, they do not provide sufficient information regarding the actual tracking errors that degrade GNSS receiver performance. Suitable receiver tracking models, sensitive to ionospheric scintillation, allow the computation of the variance of the output error of the receiver PLL (Phase Locked Loop) and DLL (Delay Locked Loop), which expresses the quality of the range measurements used by the receiver to calculate user position. The ability of such models of incorporating phase and amplitude scintillation effects into the variance of these tracking errors underpins our proposed method of applying relative weights to measurements from different satellites. That gives the least squares stochastic model used for position computation a more realistic representation, vis-a-vis the otherwise ‘equal weights’ model. For pseudorange processing, relative weights were com- puted, so that a ‘scintillation-mitigated’ solution could be performed and compared to the (non-mitigated) ‘equal weights’ solution. An improvement between 17 and 38% in height accuracy was achieved when an epoch by epoch differential solution was computed over baselines ranging from 1 to 750 km. The method was then compared with alternative approaches that can be used to improve the least squares stochastic model such as weighting according to satellite elevation angle and by the inverse of the square of the standard deviation of the code/carrier divergence (sigma CCDiv). The influence of multipath effects on the proposed mitigation approach is also discussed. With the use of high rate scintillation data in addition to the scintillation indices a carrier phase based mitigated solution was also implemented and compared with the conventional solution. During a period of occurrence of high phase scintillation it was observed that problems related to ambiguity resolution can be reduced by the use of the proposed mitigated solution. Copyright Springer Numéro de notice : A2009-430 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-009-0313-6 En ligne : https://doi.org/10.1007/s00190-009-0313-6 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=30061 [article]

Réservation

Réserver ce document

Exemplaires (1)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
266-09091	SL	Revue	Centre de documentation	Revues en salle	Disponible

On the topographic bias in geoid determination by the external gravity field / Lard Erik Sjöberg in Journal of geodesy, vol 83 n° 10 (October 2009)  

Public [article]  inJournal of geodesy > vol 83 n° 10 (October 2009) . - pp 967 - 972 Titre : On the topographic bias in geoid determination by the external gravity field Type de document : Article/Communication Auteurs : Lard Erik Sjöberg, Auteur Année de publication : 2009 Article en page(s) : pp 967 - 972 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique [Termes IGN] erreur systématique [Termes IGN] géoïde gravimétrique [Termes IGN] modèle numérique de terrain Résumé : (Auteur) The topographic bias is defined as the error/bias committed by continuing the external gravity field inside the topographic masses by a harmonic function. We study the topographic bias given by a digital terrain model defined by a spherical template, and we show that the topographic bias is given only by the potential of an inner-zone cap, and it equals the bias of the Bouguer shell, independent of the size of the cap. Then we study the effect on the real Earth by decomposing its topography into a template, and we show also in this case that the topographic bias is that of the Bouguer shell, independent of the shape of the terrain. Finally, we show that the topographic potential of the terrain at the geoid can be determined to any precision by a Taylor expansion outside the Earth’s surface. The last statement is demonstrated by a Taylor expansion to fourth order. Copyright Springer Numéro de notice : A2009-431 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-009-0314-5 En ligne : https://doi.org/10.1007/s00190-009-0314-5 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=30062 [article]

Réservation

Réserver ce document

Exemplaires (1)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
266-09091	SL	Revue	Centre de documentation	Revues en salle	Disponible

Efficient propagation of error covariance matrices of gravitational models: application to GRACE and GOCE / Georges Balmino in Journal of geodesy, vol 83 n° 10 (October 2009)  

Public [article]  inJournal of geodesy > vol 83 n° 10 (October 2009) . - pp 989 - 995 Titre : Efficient propagation of error covariance matrices of gravitational models: application to GRACE and GOCE Type de document : Article/Communication Auteurs : Georges Balmino, Auteur Année de publication : 2009 Article en page(s) : pp 989 - 995 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique [Termes IGN] données GOCE [Termes IGN] données GRACE [Termes IGN] harmonique sphérique [Termes IGN] matrice de covariance [Termes IGN] modèle de géopotentiel [Termes IGN] propagation d'erreur Résumé : (Auteur) We have applied efficient methods for computing variances and covariances of functions of a global gravity field model expanded in spherical harmonics, using the full variance–covariance matrix of the coefficients. Examples are given with recent models derived from GRACE (up to degree and order 150), and with simulated GOCE derived solutions (up to degree and order 200). Copyright Springer Numéro de notice : A2009-432 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-009-0317-2 En ligne : https://doi.org/10.1007/s00190-009-0317-2 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=30063 [article]

Réservation

Réserver ce document

Exemplaires (1)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
266-09091	SL	Revue	Centre de documentation	Revues en salle	Disponible