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Improving BeiDou real-time precise point positioning with numerical weather models / Cuixian Lu in Journal of geodesy, vol 91 n° 9 (September 2017)
[article]
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 GNSSRésumé : (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
in Journal of geodesy > vol 91 n° 9 (September 2017) . - pp 1019–1029[article]Application of ray-traced tropospheric slant delays to geodetic VLBI analysis / Armin Hofmeister in Journal of geodesy, vol 91 n° 8 (August 2017)
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Titre : Application of ray-traced tropospheric slant delays to geodetic VLBI analysis Type de document : Article/Communication Auteurs : Armin Hofmeister, Auteur ; Johannes Böhm , Auteur Année de publication : 2017 Article en page(s) : pp 945–964 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale
[Termes IGN] données ITGB
[Termes IGN] données météorologiques
[Termes IGN] interférométrie à très grande base
[Termes IGN] lancer de rayons
[Termes IGN] retard troposphériqueRésumé : (auteur) The correction of tropospheric influences via so-called path delays is critical for the analysis of observations from space geodetic techniques like the very long baseline interferometry (VLBI). In standard VLBI analysis, the a priori slant path delays are determined using the concept of zenith delays, mapping functions and gradients. The a priori use of ray-traced delays, i.e., tropospheric slant path delays determined with the technique of ray-tracing through the meteorological data of numerical weather models (NWM), serves as an alternative way of correcting the influences of the troposphere on the VLBI observations within the analysis. In the presented research, the application of ray-traced delays to the VLBI analysis of sessions in a time span of 16.5 years is investigated. Ray-traced delays have been determined with program RADIATE (see Hofmeister in Ph.D. thesis, Department of Geodesy and Geophysics, Faculty of Mathematics and Geoinformation, Technische Universität Wien. http://resolver.obvsg.at/urn:nbn:at:at-ubtuw:1-3444, 2016) utilizing meteorological data provided by NWM of the European Centre for Medium-Range Weather Forecasts (ECMWF). In comparison with a standard VLBI analysis, which includes the tropospheric gradient estimation, the application of the ray-traced delays to an analysis, which uses the same parameterization except for the a priori slant path delay handling and the used wet mapping factors for the zenith wet delay (ZWD) estimation, improves the baseline length repeatability (BLR) at 55.9% of the baselines at sub-mm level. If no tropospheric gradients are estimated within the compared analyses, 90.6% of all baselines benefit from the application of the ray-traced delays, which leads to an average improvement of the BLR of 1 mm. The effects of the ray-traced delays on the terrestrial reference frame are also investigated. A separate assessment of the RADIATE ray-traced delays is carried out by comparison to the ray-traced delays from the National Aeronautics and Space Administration Goddard Space Flight Center (NASA GSFC) (Eriksson and MacMillan in http://lacerta.gsfc.nasa.gov/tropodelays, 2016) with respect to the analysis performances in terms of BLR results. If tropospheric gradient estimation is included in the analysis, 51.3% of the baselines benefit from the RADIATE ray-traced delays at sub-mm difference level. If no tropospheric gradients are estimated within the analysis, the RADIATE ray-traced delays deliver a better BLR at 63% of the baselines compared to the NASA GSFC ray-traced delays. Numéro de notice : A2017-461 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-017-1000-7 En ligne : https://doi.org/10.1007/s00190-017-1000-7 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=86405
in Journal of geodesy > vol 91 n° 8 (August 2017) . - pp 945–964[article]Improving the modeling of the atmospheric delay in the data analysis of the Intensive VLBI sessions and the impact on the UT1 estimates / Tobias Nilsson in Journal of geodesy, vol 91 n° 7 (July 2017)
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Titre : Improving the modeling of the atmospheric delay in the data analysis of the Intensive VLBI sessions and the impact on the UT1 estimates Type de document : Article/Communication Auteurs : Tobias Nilsson, Auteur ; Benedikt Soja, Auteur ; Kyriakos Balidakis, Auteur ; Maria Karbon, Auteur ; Robert Heinkelmann, Auteur ; Zhiguo Deng, Auteur ; Harald Schuh, Auteur Année de publication : 2017 Article en page(s) : pp 857 - 866 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale
[Termes IGN] analyse de données
[Termes IGN] filtre de Kalman
[Termes IGN] gradient de troposphère
[Termes IGN] interférométrie à très grande base
[Termes IGN] longueur du jour
[Termes IGN] modèle atmosphérique
[Termes IGN] retard troposphérique zénithal
[Termes IGN] temps universelRésumé : (Auteur) The very long baseline interferometry (VLBI) Intensive sessions are typically 1-h and single-baseline VLBI sessions, specifically designed to yield low-latency estimates of UT1-UTC. In this work, we investigate what accuracy is obtained from these sessions and how it can be improved. In particular, we study the modeling of the troposphere in the data analysis. The impact of including external information on the zenith wet delays (ZWD) and tropospheric gradients from GPS or numerical weather prediction models is studied. Additionally, we test estimating tropospheric gradients in the data analysis, which is normally not done. To evaluate the results, we compared the UT1-UTC values from the Intensives to those from simultaneous 24-h VLBI session. Furthermore, we calculated length of day (LOD) estimates using the UT1-UTC values from consecutive Intensives and compared these to the LOD estimated by GPS. We find that there is not much benefit in using external ZWD; however, including external information on the gradients improves the agreement with the reference data. If gradients are estimated in the data analysis, and appropriate constraints are applied, the WRMS difference w.r.t. UT1-UTC from 24-h sessions is reduced by 5% and the WRMS difference w.r.t. the LOD from GPS by up to 12%. The best agreement between Intensives and the reference time series is obtained when using both external gradients from GPS and additionally estimating gradients in the data analysis. Numéro de notice : A2017-298 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-016-0985-7 En ligne : http://doi.org/10.1007/s00190-016-0985-7 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=85333
in Journal of geodesy > vol 91 n° 7 (July 2017) . - pp 857 - 866[article]Optimum stochastic modeling for GNSS tropospheric delay estimation in real-time / Tomasz Hadas in GPS solutions, vol 21 n° 3 (July 2017)
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Titre : Optimum stochastic modeling for GNSS tropospheric delay estimation in real-time Type de document : Article/Communication Auteurs : Tomasz Hadas, Auteur ; Felix Norman Teferle, Auteur ; Mathieu Kazmierski, Auteur ; et al., Auteur Année de publication : 2017 Article en page(s) : pp 1069 – 1081 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement du signal
[Termes IGN] données GNSS
[Termes IGN] optimisation spatiale
[Termes IGN] prévision météorologique
[Termes IGN] retard troposphérique
[Termes IGN] retard troposphérique zénithal
[Termes IGN] station GNSSRésumé : (auteur) In GNSS data processing, the station height, receiver clock and tropospheric delay (ZTD) are highly correlated to each other. Although the zenith hydrostatic delay of the troposphere can be provided with sufficient accuracy, zenith wet delay (ZWD) has to be estimated, which is usually done in a random walk process. Since ZWD temporal variation depends on the water vapor content in the atmosphere, it seems to be reasonable that ZWD constraints in GNSS processing should be geographically and/or time dependent. We propose to take benefit from numerical weather prediction models to define optimum random walk process noise. In the first approach, we used archived VMF1-G data to calculate a grid of yearly and monthly means of the difference of ZWD between two consecutive epochs divided by the root square of the time lapsed, which can be considered as a random walk process noise. Alternatively, we used the Global Forecast System model from National Centres for Environmental Prediction to calculate random walk process noise dynamically in real-time. We performed two representative experimental campaigns with 20 globally distributed International GNSS Service (IGS) stations and compared real-time ZTD estimates with the official ZTD product from the IGS. With both our approaches, we obtained an improvement of up to 10% in accuracy of the ZTD estimates compared to any uniformly fixed random walk process noise applied for all stations. Numéro de notice : A2017-443 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.1007/s10291-016-0595-0 En ligne : https://doi.org/10.1007/s10291-016-0595-0 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=86365
in GPS solutions > vol 21 n° 3 (July 2017) . - pp 1069 – 1081[article]Real-time precise point positioning augmented with high-resolution numerical weather prediction model / Karina Wilgan in GPS solutions, vol 21 n° 3 (July 2017)
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Titre : Real-time precise point positioning augmented with high-resolution numerical weather prediction model Type de document : Article/Communication Auteurs : Karina Wilgan, Auteur ; Tomasz Hadas, Auteur ; Pawel Hordyniec, Auteur ; Jaroslaw Bosy, Auteur Année de publication : 2017 Article en page(s) : pp 1341 – 1353 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale
[Termes IGN] analyse diachronique
[Termes IGN] Pologne
[Termes IGN] positionnement ponctuel précis
[Termes IGN] prévision météorologique
[Termes IGN] propagation troposphérique
[Termes IGN] réseau permanent EUREF
[Termes IGN] retard troposphérique
[Termes IGN] retard troposphérique zénithal
[Termes IGN] station GNSS
[Termes IGN] temps réelRésumé : (auteur) The tropospheric delay is one of the major error sources in precise point positioning (PPP), affecting the accuracy and precision of estimated coordinates and convergence time, which raises demand for a reliable tropospheric model, suitable to support PPP. In this study, we investigate the impact of three tropospheric models and mapping functions regarding position accuracy and convergence time. We propose a routine to constrain the tropospheric estimates, which we implemented in the in-house developed real-time PPP software. We take advantage of the high spatial resolution (4 × 4 km2) numerical weather prediction Weather Research and Forecasting (WRF) model and near real-time GNSS data combined by the least-squares collocation estimation to reconstruct the tropospheric delays. We also present mapping functions calculated from the WRF model using the ray-tracing technique. The performance tests are conducted on 14 Polish EUREF Permanent Network (EPN) stations during 3 weeks of different tropospheric conditions: calm, standard and severe. We consider six GNSS data processing variants, including two commonly used variants using a priori ZTD and mapping functions from UNB3m and VMF1-FC models, one with a priori ZTD and mapping functions calculated directly from WRF model and three variants using the aforementioned mapping functions but with ZTD model based on GNSS and WRF data used as a priori troposphere and to constrain tropospheric estimates. The application of a high-resolution GNSS/WRF-based ZTD model and mapping functions results in the best agreement with the official EPN coordinates. In both static and kinematic modes, this approach results in an average reduction of 3D bias by 20 and 10 mm, respectively, but an increase of 3D SDs by 1.5 and 4 mm, respectively. The application of high-resolution tropospheric model also shortens the convergence time, for example, for a 10 cm convergence level, from 67 to 58 min for the horizontal components and from 79 to 63 min for the vertical component. Numéro de notice : A2017-444 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.1007/s10291-017-0617-6 En ligne : https://doi.org/10.1007/s10291-017-0617-6 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=86368
in GPS solutions > vol 21 n° 3 (July 2017) . - pp 1341 – 1353[article]Study and mitigation of calibration factor instabilities in a water vapor Raman lidar / Leslie David in Atmospheric measurement techniques, vol 10 n° 7 (July 2017)PermalinkIntegrated precipitable water from GPS observations and cimel sunphotometer measurements at CGO Belsk / Michal Kruczyk in Reports on geodesy and geoinformatics, vol 103 n° 1 (June 2017)PermalinkGPS - Zenith Total Delay assimilation in different resolution simulations of a heavy precipitation event over southern France / Alberto Caldas-Álvarez in Advances in Science and Research, vol 14 (2017)PermalinkTropospheric refractivity and zenith path delays from least-squares collocation of meteorological and GNSS data / Karina Wilgan in Journal of geodesy, vol 91 n° 2 (February 2017)PermalinkModeling tropospheric wet delays with dense and sparse network configurations for PPP-RTK / Paulo S. de Oliveira in GPS solutions, vol 21 n° 1 (January 2017)PermalinkMulti-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)PermalinkReview of the state of the art and future prospects of the ground-based GNSS meteorology in Europe / Guergana Guerova in Atmospheric measurement techniques, vol 9 n° 11 (November 2016)PermalinkA new ZTD model based on permanent ground-based GNSS-ZTD data / M. Ding in Survey review, vol 48 n° 351 (October 2016)PermalinkUsing a regional numerical weather prediction model for GNSS positioning over Brazil / Daniele Barroca Marra Alves in GPS solutions, vol 20 n° 4 (October 2016)PermalinkQuantitative assessment of meteorological and tropospheric Zenith Hydrostatic Delay models / Di Zhang in Advances in space research, vol 58 n° 6 (September 2016)Permalink