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Troposphere delay modeling with horizontal gradients for satellite laser ranging / Mateusz Drożdżewski in Journal of geodesy, vol 93 n°10 (October 2019)  

Public [article]  inJournal of geodesy > vol 93 n°10 (October 2019) Titre : Troposphere delay modeling with horizontal gradients for satellite laser ranging Type de document : Article/Communication Auteurs : Mateusz Drożdżewski, Auteur ; Krzysztof Sosnica, Auteur ; Florian Zus, Auteur ; Kyriakos Balidakis, Auteur Année de publication : 2019 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale [Termes IGN] angle vertical [Termes IGN] coordonnées polaires [Termes IGN] dissymétrie [Termes IGN] erreur systématique [Termes IGN] géocentre [Termes IGN] gradient de troposphère [Termes IGN] interférométrie à très grande base [Termes IGN] Lageos [Termes IGN] retard troposphérique [Termes IGN] Sentinel-3 [Termes IGN] station TLS (télémétrie) [Termes IGN] télémètre laser sur satellite Résumé : (auteur) Satellite laser ranging (SLR) constitutes a fundamental space geodetic technique providing global geodetic parameters, such as geocenter coordinates, Earth rotation parameters, and low-degree gravity field coefficients. The tropospheric delay correction is one of the crucial corrections that have to be taken into account when processing SLR data. Current conventional models of the troposphere delays assume a full symmetry of the atmosphere above SLR stations. Neglecting horizontal gradients in SLR solutions introduces a systematic error in SLR products, especially for the observations at low elevation angles, and leads to a deterioration of the consistency between SLR and other space geodetic techniques, such as global navigational satellite systems and very-long-baseline interferometry. We derive new mapping function coefficients, as well as first- and second-order horizontal gradients, all of which are based on numerical weather models, in order to properly consider the azimuthal asymmetry in SLR solutions. We test the enhanced mapping function and horizontal gradients on the solutions based on 11 years of SLR observations to LAGEOS-1/2 satellites and 1 year of SLR observations to Sentinel-3A. The consideration of azimuthal asymmetry of the atmosphere above the SLR stations has a systematic effect on SLR-derived products, such as station and geocenter coordinates and pole coordinates. Horizontal gradients in SLR solutions improve the consistency between SLR-derived pole coordinates and the combined IERS-C04 series by means of reducing the offset for the X and Y pole coordinates by 20 μas. The second-order horizontal gradients are negligible in SLR solutions; thus, including first-order gradients is sufficient for SLR solutions. Numéro de notice : A2019-607 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-019-01287-1 Date de publication en ligne : 22/08/2019 En ligne : https://doi.org/10.1007/s00190-019-01287-1 Format de la ressource électronique : url article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=94790 [article]

Improving BeiDou real-time precise point positioning with numerical weather models / Cuixian Lu in Journal of geodesy, vol 91 n° 9 (September 2017)  

Public [article]  inJournal of geodesy > vol 91 n° 9 (September 2017) . - pp 1019–1029 Titre : Improving BeiDou real-time precise point positioning with numerical weather models Type de document : Article/Communication Auteurs : Cuixian Lu, Auteur ; Xingxing Li, Auteur ; Florian Zus, Auteur ; et al., Auteur Année de publication : 2017 Article en page(s) : pp 1019–1029 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Termes IGN] données BeiDou [Termes IGN] données météorologiques [Termes IGN] positionnement ponctuel précis [Termes IGN] précision du positionnement [Termes IGN] retard troposphérique [Termes IGN] temps réel [Vedettes matières IGN] Traitement de données GNSS Résumé : (auteur) Precise positioning with the current Chinese BeiDou Navigation Satellite System is proven to be of comparable accuracy to the Global Positioning System, which is at centimeter level for the horizontal components and sub-decimeter level for the vertical component. But the BeiDou precise point positioning (PPP) shows its limitation in requiring a relatively long convergence time. In this study, we develop a numerical weather model (NWM) augmented PPP processing algorithm to improve BeiDou precise positioning. Tropospheric delay parameters, i.e., zenith delays, mapping functions, and horizontal delay gradients, derived from short-range forecasts from the Global Forecast System of the National Centers for Environmental Prediction (NCEP) are applied into BeiDou real-time PPP. Observational data from stations that are capable of tracking the BeiDou constellation from the International GNSS Service (IGS) Multi-GNSS Experiments network are processed, with the introduced NWM-augmented PPP and the standard PPP processing. The accuracy of tropospheric delays derived from NCEP is assessed against with the IGS final tropospheric delay products. The positioning results show that an improvement in convergence time up to 60.0 and 66.7% for the east and vertical components, respectively, can be achieved with the NWM-augmented PPP solution compared to the standard PPP solutions, while only slight improvement in the solution convergence can be found for the north component. A positioning accuracy of 5.7 and 5.9 cm for the east component is achieved with the standard PPP that estimates gradients and the one that estimates no gradients, respectively, in comparison to 3.5 cm of the NWM-augmented PPP, showing an improvement of 38.6 and 40.1%. Compared to the accuracy of 3.7 and 4.1 cm for the north component derived from the two standard PPP solutions, the one of the NWM-augmented PPP solution is improved to 2.0 cm, by about 45.9 and 51.2%. The positioning accuracy for the up component improves from 11.4 and 13.2 cm with the two standard PPP solutions to 8.0 cm with the NWM-augmented PPP solution, an improvement of 29.8 and 39.4%, respectively. Numéro de notice : A2017-463 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-017-1005-2 En ligne : https://doi.org/10.1007/s00190-017-1005-2 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=86409 [article]

Multi-technique comparison of atmospheric parameters at the DORIS co-location sites during CONT14 / Robert Heinkelmann in Advances in space research, vol 58 n° 12 (15 December 2016)  

Public [article]  inAdvances in space research > vol 58 n° 12 (15 December 2016) . - pp 2758 - 2773 Titre : Multi-technique comparison of atmospheric parameters at the DORIS co-location sites during CONT14 Type de document : Article/Communication Auteurs : Robert Heinkelmann, Auteur ; Pascal Willis , Auteur ; Zhiguo Deng, Auteur ; Galina Dick, Auteur ; Tobias Nilsson, Auteur ; Benedikt Soja, Auteur ; Florian Zus, Auteur ; Jens Wickert, Auteur ; Harald Schuh, Auteur Année de publication : 2016 Article en page(s) : pp 2758 - 2773 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Systèmes de référence et réseaux [Termes IGN] analyse comparative [Termes IGN] antenne DORIS [Termes IGN] co-positionnement [Termes IGN] modèle météorologique [Termes IGN] retard troposphérique zénithal [Termes IGN] station permanente Résumé : (auteur) The atmospheric parameters, zenith delays and gradients, obtained by the DORIS, GPS, VLBI, and numerical weather models, ECMWF and NCEP, are compared at five DORIS co-located sites during the 15 days of the CONT14 campaign from 2014-05-06 until 2014-05-20. Further examined are two different solutions of GPS, VLBI and NCEP: for GPS, a network solution comparable to the TIGA reprocessing analysis strategy and a precise point positioning solution, for VLBI, a least squares and a Kalman filtered and smoothed solution, and for NCEP two spatial resolutions, 0.5° and 1.0°, are tested. The different positions of the antenna reference points at co-location sites affect the atmospheric parameters and have to be considered prior to the comparison. We assess and discuss these differences, tropospheric ties, by comparing ray-traced atmospheric parameters obtained at the positions of the various antenna reference points. While ray-traced ZHD and ZWD at the co-located antennas significantly differ, the ray-traced gradients show only very small differences. Weather events can introduce larger disagreement between atmospheric parameters obtained at co-location sites. The various weather model solutions in general agree very well in providing tropospheric ties. The atmospheric parameters are compared using statistical methods, such as the mean difference and standard deviations with repect to a weighted mean value. While GPS and VLBI atmospheric parameters agree very well in general, the DORIS observations are in several cases not dense enough to achieve a comparable level of agreement. The estimated zenith delays from DORIS, however, are competitive with the other space geodetic techniques. If the DORIS observation geometry is insufficient for the estimation of an atmospheric gradient, less than three satellites observed during the definition interval, the DORIS atmospheric parameters degrade and show small quasi-periodic variations that correlate with the number of observations and in particular with the number of satellites. An increase in the DORIS constellation concerning more satellites and in general more observations is very likely to significantly improve the quality of DORIS derived atmospheric parameters. For the first time, we tested a 6 h sampling of the DORIS gradients. Where the observations are sufficiently dense, the increased sampling results in an improvement of the agreement of the DORIS gradients with the other solutions. Numéro de notice : A2016--184 Affiliation des auteurs : LASTIG LAREG+Ext (2012-mi2018) Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.asr.2016.09.023 Date de publication en ligne : 29/09/2016 En ligne : https://doi.org/10.1016/j.asr.2016.09.023 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=91819 [article]