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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)  

Public [article]  inQuarterly Journal of the Royal Meteorological Society > vol 142 n° S1 (August 2016) . - pp 56 - 71 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 ; R. 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 descripteurs IGN] atmosphère terrestre [Termes descripteurs IGN] coordonnées GPS [Termes descripteurs IGN] données météorologiques [Termes descripteurs IGN] Méditerranée, mer [Termes descripteurs IGN] modèle atmosphérique [Termes descripteurs IGN] modèle météorologique [Termes descripteurs IGN] prévision météorologique [Termes descripteurs IGN] radiosondage [Termes descripteurs IGN] retard troposphérique zénithal [Termes descripteurs IGN] teneur intégrée en vapeur d'eau Résumé : (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 : IGN+Ext (2012-2019) 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 [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)  

Public [article]  inGPS solutions > vol 20 n° 2 (April 2016) . - pp 187 - 199 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 descripteurs IGN] analyse comparative [Termes descripteurs IGN] erreur moyenne [Termes descripteurs IGN] erreur systématique [Termes descripteurs IGN] modèle atmosphérique [Termes descripteurs IGN] positionnement ponctuel précis [Termes descripteurs IGN] retard troposphérique zénithal [Termes descripteurs IGN] temps réel [Vedettes matières IGN] Traitement de données GNSS Résumé : (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 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 [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)  

Public [article]  inApplied geomatics > vol 8 n° 1 (March 2016) . - pp 13 - 25 Titre : 14 years of GPS tropospheric delays in the French–Italian border region : comparisons and first application in a case study Type de document : Article/Communication Auteurs : Domenico Sguerso, Auteur ; Laurent Labbouz, Auteur ; Andrea Walpersdorf, Auteur Année de publication : 2016 Article en page(s) : pp 13 - 25 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Termes descripteurs IGN] Alpes [Termes descripteurs IGN] coordonnées GNSS [Termes descripteurs IGN] données météorologiques [Termes descripteurs IGN] France (administrative) [Termes descripteurs IGN] GAMIT [Termes descripteurs IGN] Italie [Termes descripteurs IGN] RENAG [Termes descripteurs IGN] réseau géodésique permanent [Termes descripteurs IGN] retard troposphérique [Termes descripteurs IGN] retard troposphérique zénithal [Termes descripteurs IGN] série temporelle [Termes descripteurs IGN] teneur intégrée en vapeur d'eau [Vedettes matières IGN] Traitement de données GNSS Résumé : (Auteur) Global Positioning System (GPS) data from 181 permanent stations extracted from different networks covering France and the Italian part of the Alps are used to estimate a homogeneous set of tropospheric parameters over 14 years (from January 1998 to May 2012). The tropospheric Zenith Total Delay (ZTD) quantified in the GPS data analysis is closely related to the value of integrated water vapor above each GPS station. GPS ZTD is already successfully used for operational weather prediction and meteorological analyses, providing valuable data to improve our comprehension of the tropospheric water cycle and in particular to improve the prediction of precipitations. Moreover, GPS tropospheric measurements are intrinsically stable, so that long-term observations represent a signi``ficant contribution to climatological studies. The results of a homogeneous reanalysis of up to 14 years of data with MIT’s GAMIT/GLOBK software are presented. The estimated tropospheric parameters are one ZTD every 2 h and one couple of horizontal tropospheric gradients, seven times a day for each station, simultaneously with a daily positioning solution. A quality check of the tropospheric parameter time series identifies offsets, for example, due to instrument changes at individual sites. Our analysis strategy using the empirical GMF is validated by a comparison with the new GPT2 model. Moreover, a comparison with the IGS analysis of 1 year is provided for common stations. The resulting verified time series can be used for meteorological and climatological studies. As first examples, we present a convergence test for the ZTD change in time and a regional climatological approach that could permit identifying specific patterns of ZTD variation that are related to severe weather events. The 181 ZTD and gradient time series are made available in the Reseau National GPS permanent (RENAG) database. Numéro de notice : A2016--056 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article En ligne : http://dx.doi.org/10.1007/s12518-015-0158-z Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=84204 [article]

Correction troposphérique des interférogrammes issus d’images radar par mesures GNSS et modèle global d’atmosphère / Vincent Dubreuil (2016)

Public Titre : Correction troposphérique des interférogrammes issus d’images radar par mesures GNSS et modèle global d’atmosphère Type de document : Mémoire Auteurs : Vincent Dubreuil, Auteur Editeur : Strasbourg : Institut National des Sciences Appliquées INSA Strasbourg Année de publication : 2016 Importance : 70 p. Format : 21 x 30 cm Note générale : Bibliographie Mémoire de fin d'études INSA Strasbourg Langues : Français (fre) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale [Termes descripteurs IGN] correction troposphérique [Termes descripteurs IGN] données GNSS [Termes descripteurs IGN] image radar moirée [Termes descripteurs IGN] interféromètrie par radar à antenne synthétique [Termes descripteurs IGN] interpolation [Termes descripteurs IGN] modèle atmosphérique [Termes descripteurs IGN] positionnement absolu [Termes descripteurs IGN] positionnement différentiel [Termes descripteurs IGN] retard troposphérique zénithal [Termes descripteurs IGN] Réunion, île de la Index. décimale : INSAS Mémoires d'ingénieur de l'INSA Strasbourg - Topographie, ex ENSAIS Résumé : (Auteur) L’équipe L2G du laboratoire GeF du CNAM/ESGT travaille sur la correction de mesures InSAR des phénomènes atmosphériques par estimations des retards troposphériques (ZTD). Pour cela, deux méthodes sont utilisées, une correction par GNSS et par modèle global d’atmosphère. Les problématiques qui se posent donc dans ce Projet de Fin d’Etudes sont la méthode d’interpolation des délais troposphériques issus du GNSS qui se doit d’être utilisée, la qualité qui peut être attendue sur les cartes interpolées et l’intérêt de la combinaison d’un modèle global d’atmosphère avec des mesures GNSS. Il en est ressorti que dans une analyse effectuée en relatif ces deux méthodes de correction s’accordent, mais qu’il existe des disparités en absolu. Note de contenu : INTRODUCTION 1. ETAT DE L'ART 1.1. Interférométrie radar 1.2. Représentation de l'atmosphère 1.3. Correction atmosphérique des mesures interférométriques 1.4. Différentes méthodes d’interpolation 2. METHODES DE TRAVAIL 2.1. Traitements et scripts réalisés 2.2. Traitement interférométrique avec le logiciel DORIS 2.3. Utilisation du GNSS en InSAR 2.4. Utilisation de l’outil TRAIN 3. PRESENTATION DU SITE DE L’ETUDE ET DES DONNEES UTILISEES 3.1. Le site de l’étude 3.2. Les données 4. APPLICATION 4.1. Les mesures interférométriques 4.2. Les mesures de délais par GNSS 4.3. Les mesures de délais par modèle d’atmosphère global ERA-Interim 4.4. Cartes corrigées CONCLUSION Numéro de notice : 22693 Affiliation des auteurs : non IGN Thématique : IMAGERIE/POSITIONNEMENT Nature : Mémoire ingénieur INSAS Note de thèse : Mémoire d'ingénieur : Topographie : Strasbourg, INSA : 2016 Organisme de stage : CNAM/ESGT Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=84830

Documents numériques

en open access 22693_Annexes Adobe Acrobat PDF

en open access 22693_Correction troposphérique des interférogrammes issus d’images radar par mesures GNSS et modèle global d’atmosphère Adobe Acrobat PDF

Static GNSS precise point positioning using free online services for Africa / Anis Abdallah in Survey review, vol 48 n° 346 (January 2016)  

Public [article]  inSurvey review > vol 48 n° 346 (January 2016) . - pp. 61 - 77 Titre : Static GNSS precise point positioning using free online services for Africa Type de document : Article/Communication Auteurs : Anis Abdallah, Auteur ; B. V. Schwieger, Auteur Année de publication : 2016 Article en page(s) : pp. 61 - 77 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Navigation et positionnement [Termes descripteurs IGN] Afrique (géographie politique) [Termes descripteurs IGN] positionnement par GNSS [Termes descripteurs IGN] positionnement ponctuel précis [Termes descripteurs IGN] positionnement statique [Termes descripteurs IGN] retard troposphérique zénithal [Termes descripteurs IGN] service fondé sur la position [Termes descripteurs IGN] station GNSS Résumé : (auteur) The GNSS precise point positioning (PPP) technique has been extensively covered in recent research. In this study, six International global navigation satellite system (GNSS) Service (IGS) stations defined by 4-digits code in Africa were selected to be processed. The stations cover different climates in Africa. HARB, SUTH and WIND stations cover the mid-latitude area and NKLG, NURK and MAL2 are located in the equatorial region. Two data sessions were selected in processing to cover the winter and summer seasons: the first session of 3 days [01–03 January 2013 (DOY: 001–003/2013)] and the second session of 3 days [01–03 July 2013 (DOY: 182–184/2013)]. This paper aims to evaluate the accuracy of static PPP coordinate solution in Africa for different convergence times using free online services: Canadian Spatial Reference System (CSRS)-PPP, Automatic Precise Point Service (APPS)-PPP and GPS Analysis and Positioning Software (GAPS)-PPP. The stations’ observation times were divided into different observation times (1, 2, 4, 8, 12, and 24 h).The PPP coordinate solution was compared to the reference solution of those stations. The investigation is continued by estimating the PPP total tropospheric zenith delay (TZD) parameters, which were obtained by the different online services. These parameters were compared to the published parameters from IGS. The comparison between the different online services shows that the CSRS-PPP provides the best solution after 4 and 8 h. The APPS-PPP and CSRS-PPP provides the same solution in millimeters level after 12 h. In the equatorial region, the PPP coordinate solution is significantly improved between 12 and 24 h. Moreover, GAPS-PPP is not recommended to be used in the equatorial stations, where it shows a high error compared to CSRS-PPP and APPS-PPP even after 24 h. The mid-latitude stations show a better PPP coordinate solution in the winter than in the summer, but the equatorial stations present a low accuracy for the two sessions. Regarding the PPP tropospheric delay estimation, an additional station (HNUS) is used in the mid-latitude area, which has a low ellipsoidal height. APPS-PPP shows the best solution in the TZD estimation. The GAPS-PPP online service shows a systemic error in estimation and a high RMS relative to the TZD values known from IGS. The ellipsoidal height for antenna indicates a negative correlation to the estimated tropospheric values, but there is no effect for the variation of the ellipsoidal height in the estimated RMS. The estimated tropospheric parameters are correlated with the PPP coordinate estimation, where the GAPS-PPP service provides the worst PPP coordinate solution and at the same time, it shows the worst accuracy for tropospheric parameters estimation. Moreover, the estimated tropospheric parameters for the mid-latitude stations in the summer season show a higher RMS than in the winter season, which matches the same sequence of the PPP coordinates. The NKLG and NURK stations present a low accuracy for the tropospheric estimation, which is matching to the low accuracy of the PPP coordinates obtained from the different online services. Numéro de notice : A2016-046 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.1080/00396265.2015.1097595 En ligne : https://doi.org/10.1080/00396265.2015.1097595 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=79639 [article]

Multi-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)  

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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)  

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Impacts 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)  

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Comparison of individual and combined zenith tropospheric delay estimations during CONT08 campaign / Arnaud Pollet in Journal of geodesy, vol 88 n° 11 (November 2014)  

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A 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)  

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Integrated Precipitable Water from GNSS as a climate parameter / Michal Kruczyk in Geoinformation issues, vol 6 n° 1 (2014)  

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DORIS tropospheric estimation at IGN : Current strategies, GPS intercomparisons and perspectives / Pascal Willis (2014)  

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GNSS meteorology in spatially dense networks / Fabian Peter Hurter (2014)  

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DORIS and GPS monitoring of the Gavdos calibration site in Crete / Pascal Willis in Advances in space research, vol 51 n° 8 (April 2013)  

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E-GVAP, un proyecto europeo meteorológico con GNSS. Participación del IGN / Marcelino Valdés Pérez de Vargas in Topografia y cartografia, vol 28 n° 165 (2013) 

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