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Time variable Earth’s gravity field from SLR satellites / Krzysztof Sosnica in Journal of geodesy, vol 89 n° 10 (october 2015)  

Public [article]  inJournal of geodesy > vol 89 n° 10 (october 2015) . - pp 945 - 960 Titre : Time variable Earth’s gravity field from SLR satellites Type de document : Article/Communication Auteurs : Krzysztof Sosnica, Auteur ; Adrian Jäggi, Auteur ; Ulrich Meyer, Auteur ; et al., Auteur Année de publication : 2015 Article en page(s) : pp 945 - 960 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique [Termes IGN] analyse comparative [Termes IGN] champ de pesanteur terrestre [Termes IGN] données GRACE [Termes IGN] masse d'air [Termes IGN] masse d'eau [Termes IGN] masse de la Terre Résumé : (auteur) The time variable Earth’s gravity field contains information about the mass transport within the system Earth, i.e., the relationship between mass variations in the atmosphere, oceans, land hydrology, and ice sheets. For many years, satellite laser ranging (SLR) observations to geodetic satellites have provided valuable information of the low-degree coefficients of the Earth’s gravity field. Today, the Gravity Recovery and Climate Experiment (GRACE) mission is the major source of information for the time variable field of a high spatial resolution. We recover the low-degree coefficients of the time variable Earth’s gravity field using SLR observations up to nine geodetic satellites: LAGEOS-1, LAGEOS-2, Starlette, Stella, AJISAI, LARES, Larets, BLITS, and Beacon-C. We estimate monthly gravity field coefficients up to degree and order 10/10 for the time span 2003–2013 and we compare the results with the GRACE-derived gravity field coefficients. We show that not only degree-2 gravity field coefficients can be well determined from SLR, but also other coefficients up to degree 10 using the combination of short 1-day arcs for low orbiting satellites and 10-day arcs for LAGEOS-1/2. In this way, LAGEOS-1/2 allow recovering zonal terms, which are associated with long-term satellite orbit perturbations, whereas the tesseral and sectorial terms benefit most from low orbiting satellites, whose orbit modeling deficiencies are minimized due to short 1-day arcs. The amplitudes of the annual signal in the low-degree gravity field coefficients derived from SLR agree with GRACE K-band results at a level of 77 %. This implies that SLR has a great potential to fill the gap between the current GRACE and the future GRACE Follow-On mission for recovering of the seasonal variations and secular trends of the longest wavelengths in gravity field, which are associated with the large-scale mass transport in the system Earth. Numéro de notice : A2015-878 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-015-0825-1 En ligne : https://doi.org/10.1007/s00190-015-0825-1 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=79410 [article]

BeiDou phase bias estimation and its application in precise point positioning with triple-frequency observable / Shengfeng Gu in Journal of geodesy, vol 89 n° 10 (october 2015)  

Public [article]  inJournal of geodesy > vol 89 n° 10 (october 2015) . - pp 979 - 992 Titre : BeiDou phase bias estimation and its application in precise point positioning with triple-frequency observable Type de document : Article/Communication Auteurs : Shengfeng Gu, Auteur ; Yidong Lou, Auteur ; Chuang Shi, Auteur ; Jingnan Liu, Auteur Année de publication : 2015 Article en page(s) : pp 979 - 992 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Termes IGN] BeiDou [Termes IGN] positionnement par BeiDou [Termes IGN] positionnement ponctuel précis [Termes IGN] résolution d'ambiguïté [Vedettes matières IGN] Traitement de données GNSS Résumé : (auteur) At present, the BeiDou system (BDS) enables the practical application of triple-frequency observable in the Asia-Pacific region, of many possible benefits from the additional signal; this study focuses on exploiting the contribution of zero difference (ZD) ambiguity resolution (AR) to the precise point positioning (PPP). A general modeling strategy for multi-frequency PPP AR is presented, in which, the least squares ambiguity decorrelation adjustment (LAMBDA) method is employed in ambiguity fixing based on the full variance-covariance ambiguity matrix generated from the raw data processing model. Because of the reliable fixing of BDS L1 ambiguity faces more difficulty, the LAMBDA method with partial ambiguity fixing is proposed to enable the independent and instantaneous resolution of extra wide-lane (EWL) and wide-lane (WL). This mechanism of sequential ambiguity fixing is demonstrated for resolving ZD satellite phase bias and performing triple-frequency PPP AR with two reference station networks with a typical baseline of up to 400 and 800 km, respectively. Tests show that about 90% of the EWL and WL phase bias of BDS has a consistency of better than 0.1 cycle, and this value decreases to Numéro de notice : A2015-879 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-015-0827-z Date de publication en ligne : 23/06/2015 En ligne : https://doi.org/10.1007/s00190-015-0827-z Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=79411 [article]

Estimating the yaw-attitude of an BDS IGSO and MEO satellites / Xiaolei Dai in Journal of geodesy, vol 89 n° 10 (october 2015)  

Public [article]  inJournal of geodesy > vol 89 n° 10 (october 2015) . - pp 1005-1018 Titre : Estimating the yaw-attitude of an BDS IGSO and MEO satellites Type de document : Article/Communication Auteurs : Xiaolei Dai, Auteur ; Maorong Ge, Auteur ; Yidong Lou, Auteur ; et al., Auteur Année de publication : 2015 Article en page(s) : pp 1005-1018 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Techniques orbitales [Termes IGN] constellation BeiDou [Termes IGN] instabilité du vecteur (télédétection) [Termes IGN] lacet [Termes IGN] orbitographie [Termes IGN] orientation du capteur [Termes IGN] positionnement par BeiDou [Termes IGN] positionnement ponctuel précis Résumé : (auteur) Precise knowledge and consistent modeling of the yaw-attitude of GNSS satellites are essential for high-precision data processing and applications. As the exact attitude control mechanism for the satellites of the BeiDou Satellite Navigation System (BDS) is not yet released, the reverse kinematic precise point positioning (PPP) method was applied in our study. However, we confirm that the recent precise orbit determination (POD) processing for GPS satellites could not provide suitable products for estimating BDS attitude using the reverse PPP because of the special attitude control switching between the nominal and the orbit-normal mode. In our study, we propose a modified processing schema for studying the attitude behavior of the BDS satellites. In this approach, the observations of the satellites during and after attitude switch are excluded in the POD processing, so that the estimates, which are needed in the reverse PPP, are not contaminated by the inaccurate initial attitude mode. The modified process is validated by experimental data sets and the attitude yaw-angles of the BDS IGSO and MEO satellites are estimated with an accuracy of better than 9∘. Furthermore, the results confirm that the switch is executed when the Sun elevation is about 4∘ and the actual orientation is very close to its target one. Based on the estimated yaw-angles, a preliminary attitude switch model was established and reintroduced into the POD, yielding to a substantial improvement in the orbit overlap RMS. Numéro de notice : A2015-880 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-015-0829-x En ligne : https://doi.org/10.1007/s00190-015-0829-x Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=79412 [article]

A surface spherical harmonic expansion of gravity anomalies on the ellipsoid / S.J. Claessens in Journal of geodesy, vol 89 n° 10 (october 2015)  

Public [article]  inJournal of geodesy > vol 89 n° 10 (october 2015) . - pp 1035 - 1048 Titre : A surface spherical harmonic expansion of gravity anomalies on the ellipsoid Type de document : Article/Communication Auteurs : S.J. Claessens, Auteur ; C. Hirt, Auteur Année de publication : 2015 Article en page(s) : pp 1035 - 1048 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique [Termes IGN] anomalie de pesanteur [Termes IGN] ellipsoïde de référence [Termes IGN] ellipsoïde GRS 1980 [Termes IGN] harmonique sphérique [Termes IGN] transformation Résumé : (auteur) A surface spherical harmonic expansion of gravity anomalies with respect to a geodetic reference ellipsoid can be used to model the global gravity field and reveal its spectral properties. In this paper, a direct and rigorous transformation between solid spherical harmonic coefficients of the Earth’s disturbing potential and surface spherical harmonic coefficients of gravity anomalies in ellipsoidal approximation with respect to a reference ellipsoid is derived. This transformation cannot rigorously be achieved by the Hotine–Jekeli transformation between spherical and ellipsoidal harmonic coefficients. The method derived here is used to create a surface spherical harmonic model of gravity anomalies with respect to the GRS80 ellipsoid from the EGM2008 global gravity model. Internal validation of the model shows a global RMS precision of Numéro de notice : A2015-881 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-015-0832-2 Date de publication en ligne : 17/06/2015 En ligne : https://doi.org/10.1007/s00190-015-0832-2 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=79413 [article]