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Termes IGN > sciences naturelles > physique > optique > optique physique > radiométrie > rayonnement électromagnétique > propagation troposphérique > retard troposphérique > retard troposphérique zénithal
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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)
[article]
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 permanenteRésumé : (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
in Advances in space research > vol 58 n° 12 (15 December 2016) . - pp 2758 - 2773[article]A new ZTD model based on permanent ground-based GNSS-ZTD data / M. Ding in Survey review, vol 48 n° 351 (October 2016)
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Titre : A new ZTD model based on permanent ground-based GNSS-ZTD data Type de document : Article/Communication Auteurs : M. Ding, Auteur ; W. Hu, Auteur ; X. Jin, Auteur ; L. Yu, Auteur Année de publication : 2016 Article en page(s) : pp 385 - 391 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Navigation et positionnement
[Termes IGN] correction troposphérique
[Termes IGN] données GNSS
[Termes IGN] réseau neuronal artificiel
[Termes IGN] retard troposphérique zénithal
[Termes IGN] RussieRésumé : (Auteur) Tropospheric delay has a major effect on the accuracy of navigation and positioning when using the Global Navigation Satellite System (GNSS). Zenith tropospheric delay (ZTD) modelling has been used to weaken the influence of the atmosphere. The work reported here focused on ZTD modelling based on real-time surface meteorological parameters, traditionally represented by the Saastamoinen model. However, Saastamoinen accuracy only reaches scale of centimetres, even to scale of centimetres when the water vapour is active, whereas the scale of ground-based GNSS-ZTD data (i.e. ZTD derived from ground GNSS data) is on the millimetre scale and is considered to be the ‘true’ value. An important direction in GNSS studies is how to make good use of ground-based GNSS-ZTD data to improve the accuracy of the Saastamoinen model. Authors studied the residuals in the Saastamoinen model using high-precision GNSS-ZTD data provided by the International GNSS Service (IGS) product and then carried out modelling based on a back propagation neural network. A new ZTD model (ISAAS) based on real-time surface meteorological parameters is proposed based on this method. The ISAAS model has good accuracy: its BIAS and root mean square error (RMSE) at the test area in Russia were -4.4 and 20.4 mm, respectively, which are lower than the results obtained using the Saastamoinen model (-10.4 and 23.3 mm, respectively). The ISAAS model can improve the ZTD prediction accuracy by more than 12.4% and therefore has important implications for precision engineering measurements in Russia. Numéro de notice : A2016-821 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.1179/1752270615Y.0000000034 En ligne : https://doi.org/10.1179/1752270615Y.0000000034 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=82636
in Survey review > vol 48 n° 351 (October 2016) . - pp 385 - 391[article]Quantitative assessment of meteorological and tropospheric Zenith Hydrostatic Delay models / Di Zhang in Advances in space research, vol 58 n° 6 (September 2016)
[article]
Titre : Quantitative assessment of meteorological and tropospheric Zenith Hydrostatic Delay models Type de document : Article/Communication Auteurs : Di Zhang, Auteur ; Jiming Guo, Auteur ; Ming Chen, Auteur ; Junbo Shi, Auteur ; Lv Zhou, Auteur Année de publication : 2016 Article en page(s) : pp 1033 - 1043 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Termes IGN] analyse comparative
[Termes IGN] erreur systématique
[Termes IGN] évaluation
[Termes IGN] modèle atmosphérique
[Termes IGN] modèle numérique
[Termes IGN] radiosondage
[Termes IGN] retard troposphérique
[Termes IGN] retard troposphérique zénithal
[Vedettes matières IGN] Traitement de données GNSSRésumé : (auteur) Tropospheric delay has always been an important issue in GNSS/DORIS/VLBI/InSAR processing. Most commonly used empirical models for the determination of tropospheric Zenith Hydrostatic Delay (ZHD), including three meteorological models and two empirical ZHD models, are carefully analyzed in this paper. Meteorological models refer to UNB3m, GPT2 and GPT2w, while ZHD models include Hopfield and Saastamoinen. By reference to in-situ meteorological measurements and ray-traced ZHD values of 91 globally distributed radiosonde sites, over a four-years period from 2010 to 2013, it is found that there is strong correlation between errors of model-derived values and latitudes. Specifically, the Saastamoinen model shows a systematic error of about −3 mm. Therefore a modified Saastamoinen model is developed based on the “best average” refractivity constant, and is validated by radiosonde data. Among different models, the GPT2w and the modified Saastamoinen model perform the best. ZHD values derived from their combination have a mean bias of −0.1 mm and a mean RMS of 13.9 mm. Limitations of the present models are discussed and suggestions for further improvements are given. Numéro de notice : A2016-593 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.asr.2016.05.055 En ligne : http://dx.doi.org/10.1016/j.asr.2016.05.055 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=81750
in Advances in space research > vol 58 n° 6 (September 2016) . - pp 1033 - 1043[article]A high-quality reprocessed ground-based GPS dataset for atmospheric process studies, radiosonde and model evaluation, and reanalysis of HyMeX Special Observing Period / Olivier Bock in Quarterly Journal of the Royal Meteorological Society, vol 142 n° S1 (August 2016)
[article]
Titre : A high-quality reprocessed ground-based GPS dataset for atmospheric process studies, radiosonde and model evaluation, and reanalysis of HyMeX Special Observing Period Type de document : Article/Communication Auteurs : Olivier Bock , Auteur ; Pierre Bosser , Auteur ; Rosa Pacione, Auteur ; Mathieu Nuret, Auteur ; Nadia Fourrié, Auteur ; Ana-Claudia Bernardes Parracho , Auteur Année de publication : 2016 Article en page(s) : pp 56 - 71 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale
[Termes IGN] atmosphère terrestre
[Termes IGN] coordonnées GPS
[Termes IGN] données météorologiques
[Termes IGN] Méditerranée, mer
[Termes IGN] modèle atmosphérique
[Termes IGN] modèle météorologique
[Termes IGN] prévision météorologique
[Termes IGN] radiosondage
[Termes IGN] retard troposphérique zénithal
[Termes IGN] teneur intégrée en vapeur d'eauRésumé : (auteur) In the framework of the Hydrological cycle in the Mediterranean Experiment (HyMeX) project, measurements from more than 1000 ground-based Global Positioning System (GPS) receivers located in the northwestern Mediterranean area are reprocessed using a single piece of GPS software for the period from 1 September 2012 to 31 March 2013. A special screening procedure is developed for the removal of outliers in the GPS Zenith Total Delay (ZTD) data. ZTD data are converted to integrated water vapour (IWV) using surface pressure information from an AROME-WMED operational analysis. The reprocessed ZTD and IWV data are used to assess the accuracy of the near-real time E-GVAP ZTD data assimilated in operational numerical weather prediction systems and to validate the IWV data from the AROME-WMED operational analysis and AROME-WMED reanalysis 1, and from radiosonde observations. The mean differences between E-GVAP and reprocessed ZTD data are not negligible and lie in the range from −3 to +3 mm. The standard deviations of differences are between 4 and 8 mm. The comparisons of IWV from AROME-WMED analyses and the reprocessed GPS data show high quality of the analyses where operational GPS data are assimilated and lower quality where no GPS data are assimilated. Small but significant biases are found in the radiosonde data during daytime (−0.5 to +1.4 kg m−2), but their origin is not determined so far. Thanks to the high spatial density of the reprocessed GPS stations, both the large-scale and small-scale variations in IWV can be documented. The case of HyMeX Intensive Observing Period 8 is presented as an example of a heavy precipitation event. This work suggests that improved quality of the humidity fields can be expected of the future AROME-WMED reanalysis 2 as a result of the assimilation of the reprocessed GPS data. Numéro de notice : A2016-938 Affiliation des auteurs : LASTIG LAREG+Ext (2012-mi2018) Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1002/qj.2701 Date de publication en ligne : 04/11/2015 En ligne : http://dx.doi.org/10.1002/qj.2701 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=83370
in Quarterly Journal of the Royal Meteorological Society > vol 142 n° S1 (August 2016) . - pp 56 - 71[article]Comparative analysis of real-time precise point positioning zenith total delay estimates / F.A. Ahmed in GPS solutions, vol 20 n° 2 (April 2016)
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Titre : Comparative analysis of real-time precise point positioning zenith total delay estimates Type de document : Article/Communication Auteurs : F.A. Ahmed, Auteur ; Pavel Vaclavovic, Auteur ; Felix Norman Teferle, Auteur ; Jan Douša, Auteur ; R.M. Bingley, Auteur ; Denis Laurichesse, Auteur Année de publication : 2016 Article en page(s) : pp 187 - 199 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Termes IGN] analyse comparative
[Termes IGN] erreur moyenne
[Termes IGN] erreur systématique
[Termes IGN] modèle atmosphérique
[Termes IGN] positionnement ponctuel précis
[Termes IGN] retard troposphérique zénithal
[Termes IGN] temps réel
[Vedettes matières IGN] Traitement de données GNSSRésumé : (Auteur) The continuous evolution of global navigation satellite systems (GNSS) meteorology has led to an increased use of associated observations for operational modern low-latency numerical weather prediction (NWP) models, which assimilate GNSS-derived zenith total delay (ZTD) estimates. The development of NWP models with faster assimilation cycles, e.g., 1-h assimilation cycle in the rapid update cycle NWP model, has increased the interest of the meteorological community toward sub-hour ZTD estimates. The suitability of real-time ZTD estimates obtained from three different precise point positioning software packages has been assessed by comparing them with the state-of-the-art IGS final troposphere product as well as collocated radiosonde (RS) observations. The ZTD estimates obtained by BNC2.7 show a mean bias of 0.21 cm, and those obtained by the G-Nut/Tefnut software library show a mean bias of 1.09 cm to the IGS final troposphere product. In comparison with the RS-based ZTD, the BNC2.7 solutions show mean biases between 1 and 2 cm, whereas the G-Nut/Tefnut solutions show mean biases between 2 and 3 cm with the RS-based ZTD, and the ambiguity float and ambiguity fixed solutions obtained by PPP-Wizard have mean biases between 6 and 7 cm with the references. The large biases in the time series from PPP-Wizard are due to the fact that this software has been developed for kinematic applications and hence does not apply receiver antenna eccentricity and phase center offset (PCO) corrections on the observations. Application of the eccentricity and PCO corrections to the a priori coordinates has resulted in a 66 % reduction of bias in the PPP-Wizard solutions. The biases are found to be stable over the whole period of the comparison, which are criteria (rather than the magnitude of the bias) for the suitability of ZTD estimates for use in NWP nowcasting. A millimeter-level impact on the ZTD estimates has also been observed in relation to ambiguity resolution. As a result of a comparison with the established user requirements for NWP nowcasting, it was found that both the G-Nut/Tefnut solutions and one of the BNC2.7 solutions meet the threshold requirements, whereas one of the BNC2.7 solution and both the PPP-Wizard solutions currently exceed this threshold. Numéro de notice : A2016-611 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.1007/s10291-014-0427-z En ligne : http://dx.doi.org/10.1007/s10291-014-0427-z Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=81810
in GPS solutions > vol 20 n° 2 (April 2016) . - pp 187 - 199[article]14 years of GPS tropospheric delays in the French–Italian border region : comparisons and first application in a case study / Domenico Sguerso in Applied geomatics, vol 8 n° 1 (March 2016)PermalinkCorrection troposphérique des interférogrammes issus d’images radar par mesures GNSS et modèle global d’atmosphère / Vincent Dubreuil (2016)PermalinkStatic GNSS precise point positioning using free online services for Africa / Anis Abdallah in Survey review, vol 48 n° 346 (January 2016)PermalinkMulti-GNSS meteorology : real-time retrieving of atmospheric water vapor from BeiDou, Galileo, GLONASS, and GPS observations / Xingxing Li in IEEE Transactions on geoscience and remote sensing, vol 53 n° 12 (December 2015)PermalinkReal-time retrieval of precipitable water vapor from GPS and BeiDou observations / Cuixian Lu in Journal of geodesy, vol 89 n° 9 (september 2015)PermalinkImpacts of real-time satellite clock errors on GPS precise point positioning-based troposphere zenith delay estimation / Junbo Shi in Journal of geodesy, vol 89 n° 8 (August 2015)PermalinkComparison of individual and combined zenith tropospheric delay estimations during CONT08 campaign / Arnaud Pollet in Journal of geodesy, vol 88 n° 11 (November 2014)PermalinkA high-quality, homogenized, global, long-term (1993–2008) DORIS precipitable water data set for climate monitoring and model verification / Olivier Bock in Journal of geophysical research : Atmospheres, vol 119 n° 12 (2014)PermalinkIntegrated Precipitable Water from GNSS as a climate parameter / Michal Kruczyk in Geoinformation issues, vol 6 n° 1 (2014)PermalinkDORIS tropospheric estimation at IGN : Current strategies, GPS intercomparisons and perspectives / Pascal Willis (2014)Permalink