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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)
[article]
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 TerreRésumé : (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
in Journal of geodesy > vol 89 n° 10 (october 2015) . - pp 945 - 960[article]Reducing leakage error in GRACE-observed long-term ice mass change: a case study in West Antarctica / J. L. Chen in Journal of geodesy, vol 89 n° 9 (september 2015)
[article]
Titre : Reducing leakage error in GRACE-observed long-term ice mass change: a case study in West Antarctica Type de document : Article/Communication Auteurs : J. L. Chen, Auteur ; C. R. Wilson, Auteur ; Jin Li, Auteur ; Zizhan Zhang, Auteur Année de publication : 2015 Article en page(s) : pp 925 - 940 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique
[Termes IGN] Antarctique
[Termes IGN] données GRACE
[Termes IGN] erreur systématique
[Termes IGN] force de gravitation
[Termes IGN] harmonique sphérique
[Termes IGN] iceberg
[Termes IGN] masse
[Termes IGN] zone polaireRésumé : (auteur) Spatial leakage is a major limitation for quantitative interpretation of satellite gravity measurements from the gravity recovery and climate experiment (GRACE). Using synthetic data to simulate ice mass changes in the Amundsen Sea Embayment and Antarctic Peninsula, we analyze quantitatively the effects of a limited range of spherical harmonics (SH) coefficients and additional filtering, which in combination can significantly attenuate signal amplitudes. We present details of a forward modeling algorithm and show that it is capable of removing these biases from GRACE estimates. Examples show how to implement the method by constraining locations of presumed mass changes, or leaving these locations unspecified within a continental region. Our analysis indicates that leakage effects from far-field mass signals (e.g., terrestrial water storage change and glacial melting over other continents) on Antarctic mass rate estimates appear to be negligible. However, leakage from long-term ocean bottom pressure change in the surrounding Antarctic Circumpolar Current regions may bias Antarctic mass rate estimates by up to 20 Gigatonne per year (Gt/year). Experiments based on proxy GRACE measurement noise indicate that the effects of GRACE spatial noise on estimated Antarctic mass rates via constrained and unconstrained forward modelings are ∼5 and 15 Gt/year, respectively. Numéro de notice : A2015-877 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-015-0824-2 Date de publication en ligne : 22/05/2015 En ligne : https://doi.org/10.1007/s00190-015-0824-2 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=79407
in Journal of geodesy > vol 89 n° 9 (september 2015) . - pp 925 - 940[article]Using ionospheric corrections from the space-based augmentation systems for low earth orbiting satellites / Jeongrae Kim in GPS solutions, vol 19 n° 3 (July 2015)
[article]
Titre : Using ionospheric corrections from the space-based augmentation systems for low earth orbiting satellites Type de document : Article/Communication Auteurs : Jeongrae Kim, Auteur ; Young Jae, Auteur Année de publication : 2015 Article en page(s) : pp 423 - 431 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Technologies spatiales
[Termes IGN] correction ionosphérique
[Termes IGN] données GRACE
[Termes IGN] European Geostationary Navigation Overlay Service
[Termes IGN] orbite basse
[Termes IGN] orbitographie
[Termes IGN] signal GPS
[Termes IGN] système d'extension spatial
[Termes IGN] teneur totale en électrons
[Termes IGN] Wide Area Augmentation SystemRésumé : (auteur) For low earth orbit satellite global positioning systems (GPS) receivers, ionospheric delay corrections from space-based augmentation system (SBAS) can be considered for real-time use. Due to the different total electron contents between ground and low altitude orbits, a scaling factor is required to adjust the ionospheric corrections. After an analysis of the scale factor determination with GPS data from the NASA/DLR gravity recovery and climate experiment satellite is conducted, evaluations of WAAS, MSAS, and EGNOS ionospheric correction accuracies are performed. In terms of the ionospheric correction error in 2012, SBAS outperforms GPS broadcast with the reduction of 42 %. This SBAS ionospheric correction accuracy shows a high level of correlation with solar flux F10.7. Numéro de notice : A2015-462 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.1007/s10291-014-0402-8 Date de publication en ligne : 22/08/2014 En ligne : https://doi.org/10.1007/s10291-014-0402-8 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=77138
in GPS solutions > vol 19 n° 3 (July 2015) . - pp 423 - 431[article]The impact of common versus separate estimation of orbit parameters on GRACE gravity field solutions / U. Meyer in Journal of geodesy, vol 89 n° 7 (July 2015)
[article]
Titre : The impact of common versus separate estimation of orbit parameters on GRACE gravity field solutions Type de document : Article/Communication Auteurs : U. Meyer, Auteur ; Adrian Jäggi, Auteur ; Gerhard Beutler, Auteur ; Heike Bock, Auteur Année de publication : 2015 Article en page(s) : pp 685 - 696 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique
[Termes IGN] données GRACE
[Termes IGN] élément orbital
[Termes IGN] orbitographie
[Termes IGN] paramètre de temps
[Termes IGN] propagation du signal
[Termes IGN] traitement du signalRésumé : (auteur) Gravity field parameters are usually determined from observations of the GRACE satellite mission together with arc-specific parameters in a generalized orbit determination process. When separating the estimation of gravity field parameters from the determination of the satellites’ orbits, correlations between orbit parameters and gravity field coefficients are ignored and the latter parameters are biased towards the a priori force model. We are thus confronted with a kind of hidden regularization. To decipher the underlying mechanisms, the Celestial Mechanics Approach is complemented by tools to modify the impact of the pseudo-stochastic arc-specific parameters on the normal equations level and to efficiently generate ensembles of solutions. By introducing a time variable a priori model and solving for hourly pseudo-stochastic accelerations, a significant reduction of noisy striping in the monthly solutions can be achieved. Setting up more frequent pseudo-stochastic parameters results in a further reduction of the noise, but also in a notable damping of the observed geophysical signals. To quantify the effect of the a priori model on the monthly solutions, the process of fixing the orbit parameters is replaced by an equivalent introduction of special pseudo-observations, i.e., by explicit regularization. The contribution of the thereby introduced a priori information is determined by a contribution analysis. The presented mechanism is valid universally. It may be used to separate any subset of parameters by pseudo-observations of a special design and to quantify the damage imposed on the solution. Numéro de notice : A2015-354 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-015-0807-3 Date de publication en ligne : 29/03/2015 En ligne : https://doi.org/10.1007/s00190-015-0807-3 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=76777
in Journal of geodesy > vol 89 n° 7 (July 2015) . - pp 685 - 696[article]Analysis of star camera errors in GRACE data and their impact on monthly gravity field models / Pedro Inácio in Journal of geodesy, vol 89 n° 6 (June 2015)
[article]
Titre : Analysis of star camera errors in GRACE data and their impact on monthly gravity field models Type de document : Article/Communication Auteurs : Pedro Inácio, Auteur ; Pavel Ditmar, Auteur ; Roland Klees, Auteur ; Hassan Hashemi Farahani, Auteur Année de publication : 2015 Article en page(s) : pp 551 - 571 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique
[Termes IGN] acquisition de données
[Termes IGN] analyse diachronique
[Termes IGN] anomalie de pesanteur
[Termes IGN] capteur spatial
[Termes IGN] champ de pesanteur terrestre
[Termes IGN] données GRACE
[Termes IGN] erreur de mesure
[Termes IGN] impact sur les données
[Termes IGN] modèle d'erreur
[Termes IGN] orientation du capteur
[Termes IGN] propagation d'erreurRésumé : (auteur) Star cameras (SCs) on board the GRACE satellites provide information about the attitudes of the spacecrafts. This information is needed to reduce the K-band ranging data to the centre of mass of the satellites. In this paper, we analyse GRACE SC errors using two months of real data of the primary and secondary SCs. We show that the errors consist of a harmonic component, which is highly correlated with the satellite’s true anomaly, and a stochastic component. We built models of both error components, and use these models for error propagation studies. Firstly, we analyse the propagation of SC errors into inter-satellite accelerations. A spectral analysis reveals that the stochastic component exceeds the harmonic component, except in the 3–10 mHz frequency band. In this band, which contains most of the geophysically relevant signal, the harmonic error component is larger than the random component. Secondly, we propagate SC errors into optimally filtered monthly mass anomaly maps and compare them with the total error. We found that SC errors account for about 18 % of the total error. Moreover, gaps in the SC data series amplify the effect of SC errors by a factor of 5. Finally, an analysis of inter-satellite pointing angles for GRACE data between 2003 and 2010 reveals that inter-satellite ranging errors were exceptionally large during the period February 2003 till May 2003. During these months, SC noise is amplified by a factor of 3 and is a considerable source of errors in monthly GRACE mass anomaly maps. In the context of future satellite gravity missions, the noise models developed in this paper may be valuable for mission performance studies. Numéro de notice : A2015-350 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-015-0797-1 Date de publication en ligne : 03/03/2015 En ligne : https://doi.org/10.1007/s00190-015-0797-1 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=76724
in Journal of geodesy > vol 89 n° 6 (June 2015) . - pp 551 - 571[article]Geological mapping of Jharia Coalfield, India using GRACE EGM2008 gravity data : a vertical derivative approach / Jitendra Vaish in Geocarto international, vol 30 n° 3 - 4 (March - April 2015)PermalinkSequential estimation of surface water mass changes from daily satellite gravimetry data / Guillaume L. Ramilien in Journal of geodesy, vol 89 n° 3 (March 2015)PermalinkAssimilation of GRACE-derived oceanic mass distributions with a global ocean circulation model / J. Saynisch in Journal of geodesy, vol 89 n° 2 (February 2015)PermalinkGravity field processing with enhanced numerical precision for LL-SST missions / Ilias Daras in Journal of geodesy, vol 89 n° 2 (February 2015)PermalinkGravité de la Terre : des mesures aux modèles, une image de la dynamique interne / Isabelle Panet (2015)PermalinkPermalinkContinental hydrology loading observed by VLBI measurements / David Eriksson in Journal of geodesy, vol 88 n° 7 (July 2014)PermalinkLes effets de l'oscillation Nord-Atlantique sur les transferts de masse, vus par géodésie / Pierre Valty in XYZ, n° 139 (juin - août 2014)PermalinkComparisons of atmospheric mass variations derived from ECMWF reanalysis and operational fields, over 2003–2011 / E. Forootan in Journal of geodesy, vol 88 n° 5 (May 2014)PermalinkThe quest for a consistent signal in ground and GRACE gravity time-series / Michel Van Camp in Geophysical journal international, vol 197 n° 1 (April 2014)Permalink