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Real-time retrieval of precipitable water vapor from GPS and BeiDou observations / Cuixian Lu in Journal of geodesy, vol 89 n° 9 (september 2015)  

Public [article]  inJournal of geodesy > vol 89 n° 9 (september 2015) . - pp 843 - 856 Titre : Real-time retrieval of precipitable water vapor from GPS and BeiDou observations Type de document : Article/Communication Auteurs : Cuixian Lu, Auteur ; Xinging Li, Auteur ; Tobias Nilsson, Auteur ; et al., Auteur Année de publication : 2015 Article en page(s) : pp 843 - 856 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale [Termes IGN] positionnement ponctuel précis [Termes IGN] précipitation [Termes IGN] propagation troposphérique [Termes IGN] retard troposphérique zénithal [Termes IGN] signal BeiDou [Termes IGN] signal GPS [Termes IGN] vapeur d'eau Résumé : (auteur) The rapid development of the Chinese BeiDou Navigation Satellite System (BDS) brings a promising prospect for the real-time retrieval of zenith tropospheric delays (ZTD) and precipitable water vapor (PWV), which is of great benefit for supporting the time-critical meteorological applications such as nowcasting or severe weather event monitoring. In this study, we develop a real-time ZTD/PWV processing method based on Global Positioning System (GPS) and BDS observations. The performance of ZTD and PWV derived from BDS observations using real-time precise point positioning (PPP) technique is carefully investigated. The contribution of combining BDS and GPS for ZTD/PWV retrieving is evaluated as well. GPS and BDS observations of a half-year period for 40 globally distributed stations from the International GNSS Service Multi-GNSS Experiment and BeiDou Experiment Tracking Network are processed. The results show that the real-time BDS-only ZTD series agree well with the GPS-only ZTD series in general: the RMS values are about 11–16 mm (about 2–3 mm in PWV). Furthermore, the real-time ZTD derived from GPS-only, BDS-only, and GPS/BDS combined solutions are compared with those derived from the Very Long Baseline Interferometry. The comparisons show that the BDS can contribute to real-time meteorological applications, slightly less accurately than GPS. More accurate and reliable water vapor estimates, about 1.3–1.8 mm in PWV, can be obtained if the BDS observations are combined with the GPS observations in the real-time PPP data processing. The PWV comparisons with radiosondes further confirm the performance of BDS-derived real-time PWV and the benefit of adding BDS to standard GPS processing. Numéro de notice : A2015-875 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-015-0818-0 Date de publication en ligne : 28/04/2015 En ligne : https://doi.org/10.1007/s00190-015-0818-0 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=79394 [article]

Simulating the effects of quasar structure on parameters from geodetic VLBI / Stanislav S. Shabala in Journal of geodesy, vol 89 n° 9 (september 2015)  

Public [article]  inJournal of geodesy > vol 89 n° 9 (september 2015) . - pp 873 - 886 Titre : Simulating the effects of quasar structure on parameters from geodetic VLBI Type de document : Article/Communication Auteurs : Stanislav S. Shabala, Auteur ; Jamie N. McCallum, Auteur ; Lucia Plank, Auteur ; Johannes Böhm , Auteur Année de publication : 2015 Article en page(s) : pp 873 - 886 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale [Termes IGN] positionnement par GPS [Termes IGN] quasar [Termes IGN] station GPS Résumé : (auteur) We investigate the effects of quasar structure on geodetic very long baseline interferometry (VLBI) measurements. We create catalogues of simulated and real quasars with a range of structure indices, and use these to generate synthetic CONT11 observations with the Vienna VLBI Software simulator tool. We systematically investigate the effects of quasars with different amounts of source structure, and find that source structure can affect station positions at the one-millimetre level. This effect is stronger for isolated stations. Overall, source structure is found to contribute to about 10 % of the troposphere and clock effects. Our simulations confirm analytical predictions that source structure mitigation strategies must be developed in order to achieve millimetre-level VLBI position accuracy. Numéro de notice : A2015-876 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-015-0820-6 Date de publication en ligne : 13/05/2015 En ligne : https://doi.org/10.1007/s00190-015-0820-6 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=79406 [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)  

Public [article]  inJournal of geodesy > vol 89 n° 9 (september 2015) . - pp 925 - 940 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 polaire Résumé : (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 [article]