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Alerte-GNSS & météo
- est un bulletin de Atmospheric chemistry and physics Special issue - Advanced global navigation satellite systems tropospheric products for monitoring severe weather events and climate (GNSS4SWEC) [Périodique] / G. Vaughan, Éditeur scientifique ; Jonathan Jones, Éditeur scientifique ; Siebren de Haan, Éditeur scientifique ; Eric Pottiaux, Éditeur scientifique ; Olivier Bock, Éditeur scientifique ; Rosa Pacione, Éditeur scientifique ; Roeland Van Malderen, Éditeur scientifique . - 2020.Special issue jointly organized between Atmospheric Measurement Techniques, Atmospheric Chemistry and Physics, and Annales GeophysicaeLangues : Anglais (eng)
Résumé : (auteur) Since 1990, signals from global positioning system (GPS) satellites have been recorded by networks worldwide. From these GPS observations the zenith total delay (ZTD) can be computed. Using surface measurements of pressure and temperature, these ZTD values can be turned into water vapour amount and used for atmospheric research. The main aim of the COST action ES1206 “Advanced Global Navigation Satellite Systems tropospheric products for monitoring severe weather events and climate” (GNSS4SWEC) is to coordinate the research and the development of new, advanced tropospheric products derived from GNSS signal delays, exploiting the full potential of multi-GNSS (GPS, GLONASS and Galileo) water vapour estimates on a wide range of temporal and spatial scales, from real-time monitoring and forecasting of severe weather to climate research. The potential impacts of this work are great: improved severe weather forecasting, leading to a decreased risk to life and national infrastructure; improvement of climate projections also has major global significance. In addition the action will promote the use of meteorological data in GNSS positioning, navigation, and timing services. The main topics envisioned in the special issue include the following: ** The development of advanced and new GNSS tropospheric products related to multi-GNSS constellation signals for water vapour remote sensing, water vapour anisotropy (horizontal gradients, satellite slant delays, tomography, etc.), real-time/ultra-fast water vapour remote sensing in support of nowcasting, improvement of the temporal and spatial resolution capability of GNSS water vapour remote sensing. ** The exploitation of these products in numerical weather prediction (NWP) and nowcasting, such as the development of new initialization/assimilation methods in NWP, the development of forecasting tools (water vapour maps, convective indexes, alarm systems, etc.) for nowcasting and severe weather events. ** The assessment of these GNSS tropospheric products (see first point) derived from a common benchmark reference data set. ** The assessment of the standardized methods/tools for NWP/nowcasting (see second point) based on the GNSS products built on the benchmark data set. ** Exploiting re-analysed/reprocessed GNSS tropospheric products for climate studies: comparison/assimilation in the regional/ global climate models, comparisons with other in-situ, ground-based and satellite water vapour retrievals, development and assessment of homogenization methods for GNSS-based product time series, analysing the variability and trends in GNSS-based water vapour retrievals. ** Establishment of new GNSS analysis centres for monitoring the atmosphere. Submissions of papers dealing with broader GNSS4SWEC objectives are also encouraged: synergy between GNSS and GNSS radio occultation (RO), monitoring the other components of the hydrological cycle (soil moisture, snow cover, terrestrial water storage) with GNSS. Numéro de notice : sans Affiliation des auteurs : UMR IPGP-Géod+Ext (2020- ) Nature : Numéro de périodique En ligne : https://acp.copernicus.org/articles/special_issue400_89.html Format de la ressource électronique : URL bulletin Permalink : https://documentation.ensg.eu/index.php?lvl=bulletin_display&id=34331 ITRF local tie survey at Malé – Maldives (2021)
ITRF local tie survey at Malé – Maldives [Rapport] / Damien Pesce, Auteur . - version 1 . - Saint-Mandé : Institut national de l'information géographique et forestière - IGN, 2021 . - 69 p.. - (Publications techniques en géodésie; 600 82 8691) .Langues : Anglais (eng)Descripteur : [Vedettes matières IGN] Systèmes de référence et réseaux[Termes IGN] point de liaison (géodésie)[Termes IGN] rattachement[Termes IGN] station DORIS[Termes IGN] station GNSS[Termes IGN] station permanente Résumé : (auteur) The ITRF2020 realization (most recent frame of the International Terrestrial Reference System) computed by the ITRS product Centre (IGN Geodesy research team from IPGP) are the result of the reference frames combination from four space geodesy techniques (i.e. GNSS, DORIS, SLR and VLBI). One way to achieve one common frame consists in adding to the combination results from co-located sites local tie surveys. The Maldives Meteorological Service at the Male airport is equipped with a DORIS station and a GNSS station. This report describes the local tie survey carried out in September 2021 during the DORIS station installation on site and provides the associated results. Note de contenu : 1 Introduction 2 Co-location site description 3 Local tie survey description 4 Computation and data analysis 5 Results 6 Annexes Numéro de notice : 14256 Affiliation des auteurs : IGN (2020- ) Thématique : POSITIONNEMENT Nature : Rapport nature-HAL : Rapport DOI : sans Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=101376 Predicting AIS reception using tropospheric propagation forecast and machine learning (2022)
Predicting AIS reception using tropospheric propagation forecast and machine learning [Article/Communication] / Zackary Vanche, Auteur ; Ambroise Renaud, Auteur ; Aldo Napoli, Auteur . - New York : Institute of Electrical and Electronics Engineers IEEE, 2022.bibliographieLangues : Anglais (eng)Descripteur : [Termes IGN] apprentissage automatique[Termes IGN] carte thématique[Termes IGN] identification automatique[Termes IGN] navigation maritime[Termes IGN] navire[Termes IGN] récepteur[Termes IGN] troposphère Résumé : (auteur) The aim of this paper is to present a methodology for modelling and predicting the coverage of an Automatic Identification System (AIS) station based on tropospheric index forecast maps and modelling methods from machine learning. The aim of this work is to cartographically represent the areas in which the AIS signals emitted by ships will be received by a coastal station. This work contributes to the improvement of maritime situational awareness and to the detection of anomalies at sea [1], and in particular to the identification of AIS message falsifications [2] (ubiquity of a vessel by identity theft, falsification of GPS positions and deactivation of AIS). Numéro de notice : C2022-036 Affiliation des auteurs : ENSG+Ext (2020- ) Autre URL associée : vers HAL Thématique : POSITIONNEMENT Nature : Communication nature-HAL : ComAvecCL&ActesPubliésIntl DOI : 10.23919/USNC-URSI52669.2022.9887465 En ligne : https://doi.org/10.23919/USNC-URSI52669.2022.9887465 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=101606 
Apport des nouveaux systèmes GNSS de cartographie du niveau marin à l’exploitation des données altimétriques en zone côtière : application aux Pertuis Charentais et au Lagon de Nouméa [Thèse/HDR] / Clémence Chupin, Auteur ; Valérie Ballu, Directeur de thèse ; Laurent Testut, Directeur de thèse . - La Rochelle : Université de La Rochelle, 2022 . - 291 p. ; 21 x 30 cm.Bibliographie
Thèse présentée pour l'obtention du grade de Docteur de l'Université de La Rochelle, Spécialité Terre solide et enveloppes superficiellesLangues : Français (fre)Descripteur : [Termes IGN] acquisition de données[Termes IGN] analyse comparative[Termes IGN] Charente (16)[Termes IGN] données 4D[Termes IGN] données altimétriques[Termes IGN] données GNSS[Termes IGN] données marégraphiques[Termes IGN] drone[Termes IGN] écluse[Termes IGN] étalonnage des données[Termes IGN] lagon[Termes IGN] littoral atlantique (France)[Termes IGN] milieu marin[Termes IGN] niveau de la mer[Termes IGN] Nouméa[Termes IGN] positionnement absolu[Termes IGN] positionnement différentiel[Termes IGN] précision centimétrique[Termes IGN] qualité des données[Termes IGN] série temporelle[Termes IGN] signal acoustique[Vedettes matières IGN] Altimétrie Index. décimale : THESE Thèses et HDR Résumé : (Auteur) Dans un contexte de changement climatique global, la question de l’évolution du niveau marin en zone côtière est essentielle, car dans ces régions se cristallisent des enjeux sociétaux, économiques et environnementaux forts. Pour mieux comprendre la dynamique de ces zones littorales, un des défis est de faire le lien entre les mesures in-situ (notamment celles des marégraphes) et les observations globales des satellites altimétriques. Grâce au développement des techniques GNSS, il est aujourd’hui possible de concevoir des instruments capables de cartographier le niveau de la mer, comblant ainsi le manque d’informations entre la côte et le passage du satellite. Cette thèse présente l’étude approfondie de deux de ces systèmes innovants : la nappe tractée CalNaGeo et le système Cyclopée, embarqué sur le drone marin PAMELi. Grâce à un ensemble de tests approfondis, ces deux instruments ont démontré leur capacité à mesurer le niveau de la mer avec une précision centimétrique. Ces nouvelles observations in-situ offrent de nombreuses perspectives pour comprendre et évaluer la qualité des données altimétriques à l’approche de la côte. En ce sens, nous avons analysé les observations brutes ainsi que les paramètres de correction permettant d’obtenir la hauteur d’eau altimétrique dans deux zones côtières : les Pertuis Charentais et le Lagon de Nouméa. Plus particulièrement à Nouméa, les données in-situ acquises durant la campagne GEOCEAN-NC et celles des marégraphes à terre ont permis de reconstruire une longue série temporelle du niveau de la mer sous le croisement de trois traces satellites. En confrontant les données in-situ et satellite selon les méthodes développées sur les sites de calibration/validation dédiés, nous avons pu réanalyser une vingtaine d’années d’observations altimétriques et réadresser la question du niveau marin relatif et absolu dans cette région. Note de contenu : Introduction PARTIE I - LE NIVEAU MARIN EN ZONE COTIERE : ENJEUX & MESURES Chapitre 1. Le niveau marin 1.1. La variation du niveau moyen de la mer 1.2. Le niveau marin à la côte 1.3. Les projections futures Chapitre 2. L’observation du niveau marin 2.1. Surfaces marines de référence 2.2. La marégraphie 2.3. L'altimétrie 2.4. Les observations de demain Chapitre 3. Deux zones côtières d’intérêt : les Pertuis Charentais et le Lagon de Nouméa 3.1. Les Pertuis Charentais 3.2. Le lagon de Nouméa PARTIE II - INSTRUMENTATION GNSS INNOVANTE POUR LA CARTOGRAPHIE DU NIVEAU MARIN Chapitre 4. Techniques et enjeux du positionnement GNSS 4.1. Principes généraux 4.2. Le positionnement relatif 4.3. Le positionnement absolu 4.4. Positionnement GNSS pour la mesure du niveau marin Chapitre 5. PAMELi, une plateforme autonome innovante 5.1. Genèse du projet 5.2. Objectifs du projet 5.3. De premières études scientifiques Chapitre 6. CalNaGéo & Cyclopée : deux systèmes innovants de cartographie du niveau marin 6.1. Instrumentation 6.2. Qualification instrumentale 6.3. Intérêt de PAMELi et CalNaGeo pour la cartographie du niveau marin PARTIE III - COMPRENDRE ET VALIDER LES DONNEES ALTIMETRIQUES EN ZONE COTIERE Chapitre 7. Qualité des données altimétriques dans les Pertuis Charentais 7.1. Qualité du retracking 7.2. Simulateur de forme d’onde Chapitre 8. Observations in situ du niveau marin pour la comparaison altimétrique 8.1. Contexte de la mission 8.2. Mesures in situ du niveau de la mer dans le lagon 8.3.Valider les observations altimétriques avec des mesures in situ 8.4. Evolution du niveau marin au point de comparaison altimétrique Chapitre 9. Analyse et validation des données altimétriques dans le Lagon de Nouméa 9.1. Qualité des observations altimétriques 9.2. Validation des données altimétriques dans le lagon 9.3. Les données altimétriques dans le Lagon de Nouméa Conclusion Numéro de notice : 26941 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Thèse française Note de thèse : Thèse de Doctorat : Terre solide et enveloppes superficielles : Université de La Rochelle : 2022 Organisme de stage : Laboratoire Littoral Environnement et Sociétés LIENSs nature-HAL : Thèse DOI : sans Date de publication en ligne : 21/10/2022 En ligne : https://tel.archives-ouvertes.fr/tel-03824906/document Format de la ressource électronique : URL Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=102094 On enhanced PPP with single difference between-satellite ionospheric constraints
On enhanced PPP with single difference between-satellite ionospheric constraints [Article/Communication] / Yan Xiang, Auteur ; Xin Chen, Auteur ; Ling Pei, Auteur ; et al., Auteur . - 2022 . - n° 505.bibliographieLangues : Anglais (eng)in Navigation : journal of the Institute of navigation > vol 69 n° 1 (Spring 2022) . - n° 505Descripteur : [Vedettes matières IGN] Géodésie spatiale[Termes IGN] correction ionosphérique[Termes IGN] modèle stochastique[Termes IGN] positionnement ponctuel précis[Termes IGN] retard ionosphèrique[Termes IGN] simple différence[Termes IGN] temps de convergence Résumé : (auteur) Applications of precise point positioning (PPP) are limited by PPP’s long convergence time. One effective way to shorten the convergence time is to apply ionospheric constraints because of the external ionospheric information. The conventional way to do this is to apply high precision but biased ionospheric corrections. The limitations of the method are that all ionospheric constraints must be derived from the same set of reference stations to have the same data. An approach based on single differences between satellite ionospheric constraints (SDBS-IONO) is developed to address the data issue due to having no common satellite visibility. The proposed method is more flexible and scalable in terms of adding ionospheric constraints. Based on a network of about 130 stations, we validated the proposed SDBS-ION method and compared it to the conventional method. Our results confirm that the ionospheric constraints enhance the PPP convergence time significantly depending on the accuracy of ionospheric constraints. Finally, we discuss crucial factors regarding how long and accurate the effectiveness of ionospheric constraints are in reducing PPP convergence time. Numéro de notice : A2022-820 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.33012/navi.505 Date de publication en ligne : 07/11/2021 En ligne : https://doi.org/10.33012/navi.505 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=101988 - Validation of regional and global ionosphere maps from GNSS measurements versus IRI2016 during different magnetic activity [Article/Communication] / Ahmed Sedeek, Auteur . - 2022 . - pp 229 - 240.bibliographieLangues : Anglais (eng)in Journal of applied geodesy > vol 16 n° 3 (July 2022) . - pp 229 - 240
Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale[Termes IGN] Afrique du nord[Termes IGN] données GNSS[Termes IGN] harmonique sphérique[Termes IGN] International Reference Ionosphere[Termes IGN] interpolation[Termes IGN] Matlab[Termes IGN] modèle ionosphérique[Termes IGN] station GNSS[Termes IGN] teneur verticale totale en électrons Résumé : (auteur) This manuscript explores the divergence of the Vertical Total Electron Content (VTEC) estimated from Global Navigation Satellite System (GNSS) measurements using global, regional, and International Reference Ionosphere (IRI) models over low to high latitude regions during various magnetic activity. The VTEC is estimated using a territorial network consisting of 7 GNSS stations in Egypt and 10 GNSS stations from the International GNSS Service (IGS) Global network. The impact of magnetic activity on VTEC is investigated. Due to the deficiency of IGS receivers in north Africa and the shortage of GNSS measurements, an extra high interpolation is done to cover the deficit of data over North Africa. A MATLAB code was created to produce VTEC maps for Egypt utilizing a territorial network contrasted with global maps of VTEC, which are delivered by the Center for Orbit Determination in Europe (CODE). Thus we can have genuine VTEC maps estimated from actual GNSS measurements over any region of North Africa. A Spherical Harmonics Expansion (SHE) equation was modelled using MATLAB and called Local VTEC Model (LVTECM) to estimate VTEC values using observations of dual-frequency GNSS receivers. The VTEC calculated from GNSS measurement using LVTECM is compared with CODE VTEC results and IRI-2016 VTEC model results. The analysis of outcomes demonstrates a good convergence between VTEC from CODE and estimated from LVTECM. A strong correlation between LVTECM and CODE reaches about 96 % and 92 % in high and low magnetic activity, respectively. The most extreme contrasts are found to be 2.5 TECu and 1.3 TECu at high and low magnetic activity, respectively. The maximum discrepancies between LVTECM and IRI-2016 are 9.7 TECu and 2.3 TECu at a high and low magnetic activity. Variation in VTEC due to magnetic activity ranges from 1–5 TECu in moderate magnetic activity. The estimated VTEC from the regional network shows a 95 % correlation between the estimated VTEC from LVTECM and CODE with a maximum difference of 5.9 TECu. Numéro de notice : A2022-495 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.1515/jag-2021-0046 Date de publication en ligne : 09/02/2022 En ligne : https://doi.org/10.1515/jag-2021-0046 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=100985 A new ambiguity resolution method for LEO precise orbit determination
A new ambiguity resolution method for LEO precise orbit determination [Article/Communication] / Xingyu Zhou, Auteur ; Hua Chen, Auteur ; Weiping Jiang, Auteur ; et al., Auteur . - 2022 . - n° 49.bibliographieLangues : Anglais (eng)in Journal of geodesy > vol 96 n° 7 (July 2022) . - n° 49Descripteur : [Vedettes matières IGN] Techniques orbitales[Termes IGN] orbite basse[Termes IGN] orbitographie[Termes IGN] récepteur GNSS[Termes IGN] résolution d'ambiguïté Résumé : (auteur) Ambiguity resolution (AR) is an effective approach to improve the orbit accuracy of the low Earth orbit satellites using the Global Navigation Satellite System (GNSS). The most commonly used single-difference (SD) AR requires prior knowledge of the GNSS hardware biases, while the potential unavailability of the bias products may hinder the AR process for users. The track-to-track (T2T) AR can work as an alternative without the GNSS bias products, but the performance may be degraded by the receiver hardware biases. To provide a better alternative in this condition, a new AR method called SD T2T (SDT2T) is proposed in this study, where the GNSS and receiver biases can be greatly eliminated without external knowledge. The performance of the SD AR, SDT2T AR, and T2T AR methods are assessed based on the gravity recovery and climate experiment follow on and SWARM data. The results show that the improvements contributed by the SDT2T AR are comparable to the SD AR. The multiple iterations required by the T2T AR can be avoided by the SDT2T AR, and the accuracy of the T2T AR can be further improved with the preprocessed ambiguities of the SDT2T AR. Considering the efficiency and stable performance, the SDT2T AR is recommended as the preferred alternative single-receiver AR method in the absence of the GNSS hardware bias products. Numéro de notice : A2022-590 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-022-01629-6 Date de publication en ligne : 15/07/2022 En ligne : https://doi.org/10.1007/s00190-022-01629-6 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=101272 - Synergistic use of the SRAL/MWR and SLSTR sensors on board Sentinel-3 for the wet tropospheric correction retrieval [Article/Communication] / Pedro Aguiar, Auteur ; Telmo Vieira, Auteur ; Clara Lázaro, Auteur ; M. Joanna Fernandes, Auteur . - 2022 . - n° 3231.bibliographieLangues : Anglais (eng)in Remote sensing > vol 14 n° 13 (July-1 2022) . - n° 3231
Descripteur : [Vedettes matières IGN] Traitement d'image[Termes IGN] correction troposphérique[Termes IGN] image Sentinel-3[Termes IGN] température de surface de la mer Résumé : (auteur) The Sentinel-3 satellites are equipped with dual-band Microwave Radiometers (MWR) to derive the wet tropospheric correction (WTC) for satellite altimetry. The deployed MWR lack the 18 GHz channel, which mainly provides information on the surface emissivity. Currently, this information is considered using additional parameters, one of which is the sea surface temperature (SST) extracted from static seasonal tables. Recent studies show that the use of a dynamic SST extracted from Numerical Weather Models (ERA5) improves the WTC retrieval. Given that Sentinel-3 carries on board the Sea and Land Surface Temperature Radiometer (SLSTR), from which SST observations are derived simultaneously with those of the Synthetic Aperture Radar Altimeter and MWR sensors, this study aims to develop a synergistic approach between these sensors for the WTC retrieval over open ocean. Firstly, the SLSTR-derived SSTs are evaluated against the ERA5 model; secondly, their impact on the WTC retrieval is assessed. The results show that using the SST input from SLSTR, instead of ERA5, has no impact on the WTC retrieval, both globally and regionally. Thus, for the WTC retrieval, there seems to be no advantage in having collocated SST and radiometer observations. Additionally, this study reinforces the fact that the use of dynamic SST leads to a significant improvement over the current Sentinel-3 WTC operational algorithms. Numéro de notice : A2022-571 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article DOI : 10.3390/rs14133231 Date de publication en ligne : 05/07/2022 En ligne : https://doi.org/10.3390/rs14133231 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=101287 GNSSseg, a statistical method for the segmentation of daily GNSS IWV time series
GNSSseg, a statistical method for the segmentation of daily GNSS IWV time series [Article/Communication] / Annarosa Quarello, Auteur ; Olivier Bock, Auteur ; Emilie Lebarbier, Auteur . - 2022 . - n° 3379.bibliographie This work was developed in the framework of the VEGA Project and supported by the CNRS Program LEFE/INSU. The contribution of the third author has been conducted as part of the Project Labex MME-DII (ANR11-LBX-0023-01) and within the FP2M Federation (CNRS FR 2036).Langues : Anglais (eng)in Remote sensing > vol 14 n° 14 (July-2 2022) . - n° 3379Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale[Termes IGN] coordonnées GPS[Termes IGN] données météorologiques[Termes IGN] erreur systématique[Termes IGN] programmation dynamique[Termes IGN] R (langage)[Termes IGN] segmentation[Termes IGN] série temporelle[Termes IGN] teneur intégrée en vapeur d'eau Résumé : (auteur) Homogenization is an important and crucial step to improve the usage of observational data for climate analysis. This work is motivated by the analysis of long series of GNSS Integrated Water Vapour (IWV) data, which have not yet been used in this context. This paper proposes a novel segmentation method called segfunc that integrates a periodic bias and a heterogeneous, monthly varying, variance. The method consists in estimating first the variance using a robust estimator and then estimating the segmentation and periodic bias iteratively. This strategy allows for the use of the dynamic programming algorithm, which is the most efficient exact algorithm to estimate the change point positions. The performance of the method is assessed through numerical simulation experiments. It is implemented in the R package GNSSseg, which is available on the CRAN. This paper presents the application of the method to a real data set from a global network of 120 GNSS stations. A hit rate of 32% is achieved with respect to available metadata. The final segmentation is made in a semi-automatic way, where the change points detected by three different penalty criteria are manually selected. In this case, the hit rate reaches 60% with respect to the metadata. Numéro de notice : A2022-575 Affiliation des auteurs : UMR IPGP-Géod+Ext (2020- ) Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.3390/rs14143379 Date de publication en ligne : 13/07/2022 En ligne : https://doi.org/10.3390/rs14143379 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=101294 - Ground surface elevation changes over permafrost areas revealed by multiple GNSS interferometric reflectometry [Article/Communication] / Yufeng Hu, Auteur ; Ji Wang, Auteur ; Zhenhong Li, Auteur ; et al., Auteur . - 2022 . - n° 56.bibliographieLangues : Anglais (eng)in Journal of geodesy > vol 96 n° 8 (August 2022) . - n° 56
Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale[Termes IGN] Alaska (Etats-Unis)[Termes IGN] analyse diachronique[Termes IGN] dégel[Termes IGN] données Galileo[Termes IGN] données GLONASS[Termes IGN] pergélisol[Termes IGN] rapport signal sur bruit[Termes IGN] réflecteur[Termes IGN] réflectométrie par GNSS[Termes IGN] signal GNSS[Termes IGN] surface du sol[Termes IGN] variation saisonnière Résumé : (auteur) Ground subsidence and uplift caused by the annual thawing and freezing of the active layer are important variables in permafrost studies. Global positioning system interferometric reflectometry (GPS-IR) has been successfully applied to retrieve the continuous ground surface movements in permafrost areas. However, only GPS signals were used in previous studies. In this study, using multiple global navigation satellite system (GNSS) signal-to-noise ratio (SNR) observations recorded by a GNSS station SG27 in Utqiaġvik, Alaska during the period from 2018 to 2021, we applied multiple GNSS-IR (multi-GNSS-IR) technique to the SNR data and obtained the complete and continuous ground surface elevation changes over the permafrost area at a daily interval in snow-free seasons in 2018 and 2019. The GLONASS-IR and Galileo-IR measurements agreed with the GPS-IR measurements at L1 frequency, which are the most consistent measurements among all multi-GNSS measurements, in terms of the overall subsidence trend but clearly showed periodic noises. We proposed a method to reconstruct the GLONASS- and Galileo-IR elevation changes by specifically grouping and fitting them with a composite model. Compared with GPS L1 results, the unbiased root mean square error (RMSE) of the reconstructed Galileo measurements reduced by 50.0% and 42.2% in 2018 and 2019, respectively, while the unbiased RMSE of the reconstructed GLONASS measurements decreased by 41.8% and 25.8% in 2018 and 2019, respectively. Fitting the composite model to the combined multi-GNSS-IR, we obtained seasonal displacements of − 3.27 ± 0.13 cm (R2 = 0.763) and − 10.56 ± 0.10 cm (R2 = 0.912) in 2018 and 2019, respectively. Moreover, we found that the abnormal summer heave was strongly correlated with rain events, implying hydrological effects on the ground surface elevation changes. Our study shows the feasibility of multi-GNSS-IR in permafrost areas for the first time. Multi-GNSS-IR opens up a great opportunity for us to investigate ground surface movements over permafrost areas with multi-source observations, which are important for our robust analysis and quantitative understanding of frozen ground dynamics under climate change. Numéro de notice : A2022-606 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-022-01646-5 Date de publication en ligne : 13/08/2022 En ligne : https://doi.org/10.1007/s00190-022-01646-5 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=101385 - Impact assessment of the seasonal hydrological loading on geodetic movement and seismicity in Nepal Himalaya using GRACE and GNSS measurements [Article/Communication] / Devendra Shashikant Nagale, Auteur ; Suresh Kannaujiya, Auteur ; Param K. Gautam, Auteur ; et al., Auteur . - 2022 . - pp 445 - 455.bibliographieLangues : Anglais (eng)in Geodesy and Geodynamics > vol 13 n° 5 (September 2022) . - pp 445 - 455
Descripteur : [Vedettes matières IGN] Géodésie physique[Termes IGN] coefficient de corrélation[Termes IGN] déformation de la croute terrestre[Termes IGN] données GNSS[Termes IGN] données GRACE[Termes IGN] International Terrestrial Reference Frame[Termes IGN] mousson[Termes IGN] Népal[Termes IGN] pondération[Termes IGN] série temporelle[Termes IGN] sismicité[Termes IGN] surcharge hydrologique[Termes IGN] variation saisonnière Résumé : (auteur) The Himalayan terrain is an epitome of ongoing convergence and geodetic deformation where both tectonic and non-tectonic forces prevail. In this study, the Gravity Recovery and Climate Experiment (GRACE) and Global Positioning System (GPS) datasets are used to assess the impact of seasonal loading on deformation with seismicity in Nepal. The recorded GPS data from 21 Global Navigation Satellite System (GNSS) stations during 2017–2020 are processed with respect to ITRF14 and the Indian reference frame, and the Center for Space Research (CSR) mascon RL06 during 2002–2020 is adopted to estimate the terrestrial water storage (TWS) change over the Ganga-Brahmaputra River basin. The results indicate that the hydrological loading effect or TWS change shows high negative, high positive, and moderately positive values in pre-monsoon, co-monsoon, and post-monsoon months, respectively. The detrended GPS data of both horizontal and vertical components correlate with the seasonal TWS change using the Pearson correlation coefficient at each GNSS site. In addition, the correlation coefficient has been interpolated using inverse distance weighting to investigate the regional TWS influence on geodetic displacement. In the north component, the correlation coefficient ranges from −0.6 to 0.6. At the same time, the TWS is positively correlated with geodetic displacement (0.82) in the east component, and the correlation coefficient is negative (−0.69) in the vertical component. The negative correlation signifies an inverse relationship between seasonal TWS variation and geodetic displacements. The strain rate is estimated, which shows higher negative values in pre-monsoon than in post-monsoon. Similarly, the effect of seismicity is 47.90% for pre-monsoon, 15.97% for co-monsoon, and 17.56% for post-monsoon. Thus we can infer that the seismicity decreases with the increase of seasonal hydrological loading. Furthermore, the effect of strain is much higher in pre-monsoon than in post-monsoon since the impact of co-monsoon continues to persist on a small scale in the post-monsoon season. Numéro de notice : A2022-762 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.1016/j.geog.2022.02.006 Date de publication en ligne : 20/05/2022 En ligne : https://doi.org/10.1016/j.geog.2022.02.006 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=101780 Estimation of swell height using spaceborne GNSS-R data from eight CYGNSS satellites
Estimation of swell height using spaceborne GNSS-R data from eight CYGNSS satellites [Article/Communication] / Yanli Zheng, Auteur ; Fu Zheng, Auteur ; Cheng Yang, Auteur ; et al., Auteur . - 2022 . - n° 4640.bibliographieLangues : Anglais (eng)in Remote sensing > vol 14 n° 18 (September-2 2022) . - n° 4640Descripteur : [Vedettes matières IGN] Géodésie spatiale[Termes IGN] données GLONASS[Termes IGN] données GPS[Termes IGN] double différence[Termes IGN] latitude[Termes IGN] positionnement ponctuel précis[Termes IGN] positionnement statique[Termes IGN] retard troposphérique zénithal[Termes IGN] temps de convergence Résumé : (auteur) The orbital inclination angle of the GLONASS constellation is about 10° larger than that of GPS, Galileo, and BDS. Theoretically, the higher orbital inclination angle could provide better observation geometry in high latitude regions. A wealth of research has investigated the positioning accuracy of GLONASS and its impact on multi-GNSS, but rarely considered the contribution of the GLONASS constellation’s large orbit inclination angle. The performance of GLONASS in different latitude regions is evaluated in both stand-alone mode and integration with GPS in this paper. The performance of GPS is also presented for comparison. Three international GNSS service (IGS) networks located in high, middle, and low latitudes are selected for the current study. Multi-GNSS data between January 2021 and June 2021 are used for the assessment. The data quality check shows that the GLONASS data integrity is significantly lower than that of GPS. The constellation visibility analysis indicates that GLONASS has a much better elevation distribution than GPS in high latitude regions. Both daily double-difference network solutions and daily static Precise Point Positioning (PPP) solutions are evaluated. The statistical analysis of coordinate estimates indicates that, in high latitude regions, GLONASS has a comparable or even better accuracy than that of GPS, and GPS+GLONASS presents the best estimate accuracy; in middle latitude regions, GPS stand-alone constellation provides the best positioning accuracy; in low latitude regions, GLONASS offers the worst accuracy, but the positioning accuracy of GPS+GLONASS is better than that of GPS. The tropospheric estimates of GLONASS do not present a resemblance regional advantage as coordinate estimates, which is worse than that of GPS in all three networks. The PPP processing with combined GPS and GLONASS observations reduces the convergence time and improves the accuracy of tropospheric estimates in all three networks. Numéro de notice : A2022-770 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.3390/rs14184640 Date de publication en ligne : 16/09/2022 En ligne : https://doi.org/10.3390/rs14184640 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=101796 - Multi‑constellation GNSS interferometric reflectometry for the correction of long-term snow height retrieval on sloping topography [Article/Communication] / Wei Zhou, Auteur ; Liangke Huang, Auteur ; Bing Ji, Auteur ; et al., Auteur . - 2022 . - n° 140.bibliographieLangues : Anglais (eng)in GPS solutions > vol 26 n° 4 (October 2022) . - n° 140
Descripteur : [Termes IGN] hauteur (coordonnée)[Termes IGN] manteau neigeux[Termes IGN] pente[Termes IGN] Ransac (algorithme)[Termes IGN] rapport signal sur bruit[Termes IGN] réflectométrie par GNSS[Termes IGN] signal GNSS[Termes IGN] système de référence altimétrique[Termes IGN] topographie locale[Termes IGN] transformation en ondelettes[Termes IGN] valeur aberrante[Vedettes matières IGN] Altimétrie Résumé : (auteur) Snow is a key parameter for global climate and hydrological systems. Global Navigation Satellite System interferometric reflectometry (GNSS-IR) has been applied to accurately monitor snow height (SH) with low cost and high temporal–spatial resolution. We proposed an improved GNSS-IR method using detrended signal-to-noise ratio (δSNR) arcs corresponding to multipath reflection tracks with different azimuths. After using wavelet decomposition and random sample consensus, noise with various frequencies for SNR arcs and outliers of reflector height (RH) estimations have been sequentially mitigated to enhance the availability of the proposed method. Thus, a height datum based on the ground RHs retrieved from multi-GNSS SNR data is established to compensate for the influence of topography variation with different azimuths in SH retrieval. The approximately 3-month δSNR datasets collected from three stations deployed on sloping topography were used to retrieve SH and compared with the existing method and in situ measurements. The results show that the root mean square errors of the retrievals derived from the proposed method for the three sites are between 4 and 8 cm, and the corresponding correlation surpasses 0.95 when compared to the reference SH datasets. Additionally, we compare the performance of a retrieval with the existing GNSS-IR Web App, and it shows an improvement in RMSE of about 7 cm. Furthermore, because topography variation has been considered, the average correction of SH retrievals is between 2 and 4 cm. The solution with the proposed method helps develop the applications of the GNSS-IR technique on complex topography. Numéro de notice : A2022-712 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.1007/s10291-022-01333-0 Date de publication en ligne : 15/09/2022 En ligne : https://doi.org/10.1007/s10291-022-01333-0 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=101590 Estimation of ionospheric total electron content using GNSS observations derived from a smartphone
Estimation of ionospheric total electron content using GNSS observations derived from a smartphone [Article/Communication] / Li Xu, Auteur ; Jiuping Zha, Auteur ; Min Li, Auteur ; et al., Auteur . - 2022 . - n° 138.bibliographieLangues : Anglais (eng)in GPS solutions > vol 26 n° 4 (October 2022) . - n° 138Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale[Termes IGN] modèle ionosphérique[Termes IGN] phase[Termes IGN] pondération[Termes IGN] série de Fourier[Termes IGN] téléphone intelligent[Termes IGN] teneur totale en électrons[Termes IGN] teneur verticale totale en électrons Résumé : (auteur) The global navigation satellite system (GNSS) measurements to determine ionospheric total electron content (TEC) are mainly derived from expensive geodetic-grade receivers, which are not conducive to high-density placement. In this work, we present an analysis of the performance of ionospheric TEC determined by GNSS dual-frequency measurements derived from the smartphone, taking the Xiaomi 8 (XMI8) as an example. First, the ionospheric observable is retrieved from the code and carrier phase data using the carrier-to-code leveling technique and a new carrier-to-noise weighting strategy instead of an elevation weighting strategy, considering the characteristic of the GNSS measurements from smartphones. Then, the absolute ionospheric slant TEC (STEC) values are isolated from the ionospheric observables by modeling with the generalized trigonometric series function. The experimental data, covering over 120 h, were taken from two situations: one is the data collected by the original smartphone antenna; the other is the external geodetic-grade antenna. The TEC data obtained from the collocated geodetic-grade receiver are used as reference data to evaluate the performance of the TEC values from XMI8. Compared to the reference data, the evaluation results show that the ionospheric STEC extraction accuracy can reach total electron content unit (TECU) values of 0.17 and 0.11 under the two different situations in the continuous carrier phase satellite arc without cycle slips. In addition, the VTEC modeling accuracy is above 5 and 2 TECU in the two different situations, respectively. Thus, we concluded that consumer-level GNSS chipsets are highly potential in the future to increase the ionospheric monitoring station density due to their low costs and good data quality. Numéro de notice : A2022-713 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.1007/s10291-022-01329-w Date de publication en ligne : 04/09/2022 En ligne : https://doi.org/10.1007/s10291-022-01329-w Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=101591 - Toward BDS/Galileo/GPS/QZSS triple-frequency PPP instantaneous integer ambiguity resolutions without atmosphere corrections [Article/Communication] / Jun Tao, Auteur ; Guo Chen, Auteur ; Jing Guo, Auteur ; et al., Auteur . - 2022 . - n° 127.bibliographieLangues : Anglais (eng)in GPS solutions > vol 26 n° 4 (October 2022) . - n° 127
Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale[Termes IGN] ambiguïté entière[Termes IGN] correction atmosphérique[Termes IGN] erreur de phase[Termes IGN] fréquence multiple[Termes IGN] positionnement par BeiDou[Termes IGN] positionnement par Galileo[Termes IGN] positionnement par GPS[Termes IGN] positionnement ponctuel précis[Termes IGN] Quasi-Zenith Satellite System[Termes IGN] résolution d'ambiguïté[Termes IGN] temps de convergence Résumé : (auteur) Multi-frequency precise point positioning (PPP) has drawn attention along with the modernization of the Global Navigation Satellite Systems. There are now nearly 90 satellites providing multi-frequency signals. This contribution aims to achieve fast convergence of a few seconds for BDS/Galileo/GPS/QZSS integrated triple-frequency PPP with integer ambiguity resolution (IAR) without atmosphere corrections. A unified model of an uncombined and undifferenced manner for PPP-IAR with dual- and triple-frequency observations is presented. The uncalibrated phase delays (UPD) of extra wide-lane (EWL), wide-lane (WL), and N1 ambiguities for triple-frequency PPP are estimated with standard deviations of 0.02, 0.05, and 0.10 cycles achieved, respectively. The PPP-IAR validation based on 20 stations evenly distributed in China is conducted using UPD products generated from a regional network covering a large part of China. The EWL, WL, and N1 ambiguities are sequentially fixed utilizing the least-squares ambiguity decorrelation adjustment (LAMBDA) technique. In terms of convergence time, PPP instantaneous IAR is achievable without using atmosphere corrections, thanks to the contribution of the multi-frequency and multi-constellation observations. This has been proved by performing PPP-IAR restart every 10-min over 2520 times in our case study. For PPP-IAR solutions produced with BDS/Galileo/GPS/QZSS triple-frequency observations with an interval of 1 s, the convergence is fulfilled within 1 s for the horizontal components with an accuracy of better than 5 cm, while 2 s for the vertical component with better than 10 cm accuracy, and both are at 95% confidence level. Numéro de notice : A2022-714 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s10291-022-01287-3 Date de publication en ligne : 13/08/2022 En ligne : https://doi.org/10.1007/s10291-022-01287-3 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=101595 PPP rapid ambiguity resolution using Android GNSS raw measurements with a low-cost helical antenna
PPP rapid ambiguity resolution using Android GNSS raw measurements with a low-cost helical antenna [Article/Communication] / Xingxing Li, Auteur ; Hao Wang, Auteur ; Xin Li, Auteur ; et al., Auteur . - 2022 . - n° 65.bibliographieLangues : Anglais (eng)in Journal of geodesy > vol 96 n° 10 (October 2022) . - n° 65Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale[Termes IGN] Androïd[Termes IGN] antenne[Termes IGN] données GNSS[Termes IGN] positionnement cinématique en temps réel[Termes IGN] positionnement ponctuel précis[Termes IGN] précision du positionnement[Termes IGN] rapport signal sur bruit[Termes IGN] résolution d'ambiguïté[Termes IGN] téléphone intelligent Résumé : (auteur) The release of GNSS raw measurement acquisition privileges on Google Android makes high-precision positioning on the low-cost smart devices possible. However, influenced by the inner linearly polarized antenna, the pseudorange and carrier phase noises of the smart device are much larger than those of the geodetic receiver. As a result, only meter-level positioning accuracy can be obtained based on the smart device’s original antenna. With the external survey-grade antenna enhancing, positioning accuracy of decimeter-level to centimeter-level can be obtained, but it still takes tens of minutes to converge and fix the ambiguity. However, a PPP-RTK method is proposed to achieve rapid integer ambiguity resolution (AR) with the regional atmospheric augmentation. In this contribution, an uncombined PPP-RTK model is developed using Android GNSS raw measurements with an external antenna, after carefully considering the coexistence of single- and dual-frequency signals on smart devices. A low-cost helical antenna is employed to enhance the Android GNSS data as it is capable to provide observation data of comparable quality with the survey-grade antenna and has several advantages of low weight, low-power consumption, and portability. Moreover, a series of quality control methods in the data preprocessing and ambiguity resolution are proposed for smartphone-based PPP-RTK to enhance the positioning results. To validate the proposed method, several experiments are carried out using raw measurements of Xiaomi Mi8 with an external low-cost helical antenna. The result shows that the ambiguity fixed solution can be obtained within 3 min in both static and kinematic scenarios. After the ambiguity resolution, centimeter-level positioning accuracy of (1.7, 2.1, 4.1) cm and (7.2, 4.5, 8.1) cm for the east, north, and up components can be achieved in static and kinematic scenarios, respectively. Numéro de notice : A2022-735 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-022-01661-6 Date de publication en ligne : 27/09/2022 En ligne : https://doi.org/10.1007/s00190-022-01661-6 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=101706 Modelling and prediction of GNSS time series using GBDT, LSTM and SVM machine learning approaches
Modelling and prediction of GNSS time series using GBDT, LSTM and SVM machine learning approaches [Article/Communication] / Wenzong Gao, Auteur ; Zhao Li, Auteur ; Qusen Chen, Auteur ; et al., Auteur . - 2022 . - n° 71.bibliographieLangues : Anglais (eng)in Journal of geodesy > vol 96 n° 10 (October 2022) . - n° 71Descripteur : [Termes IGN] classification par réseau neuronal récurrent[Termes IGN] classification par séparateurs à vaste marge[Termes IGN] déformation de la croute terrestre[Termes IGN] données GNSS[Termes IGN] Extreme Gradient Machine[Termes IGN] modèle de simulation[Termes IGN] série temporelle[Vedettes matières IGN] Traitement de données GNSS Résumé : (auteur) Global navigation satellite system (GNSS) site coordinate time series provides essential data for geodynamic and geophysical studies, realisation of a regional or global geodetic reference frames, and crustal deformation research. The coordinate time series has been conventionally modelled by least squares (LS) fitting with harmonic functions, alongside many other analysis methods. As a key limitation, the traditional modelling approaches simply use the functions of time variable, despite good knowledge of various underlying physical mechanisms responsible for the site displacements. This paper examines the use of machine learning (ML) models to reflect the effects or residential effects of physical variables related to Sun and the Moon ephemerides, polar motion, temperature, atmospheric pressure, and hydrology on the site displacements. To form the ML problem, these variables are constructed as the input vector of each ML training sample, while the vertical displacement of a GNSS site is regarded as the output value. In the evaluation experiments, three ML approaches, namely the gradient boosting decision tree (GBDT) approach, long short-term memory (LSTM) approach, and support vector machine (SVM) approach, are introduced and evaluated with the time series datasets collected from 9 GNSS sites over the period of 13 years. The results indicate that all three approaches achieve similar fitting precision in the range of 3–5 mm in the vertical displacement component, which is an improvement in over 30% with respect to the traditional LS fitting precision in the range of 4–7 mm. The prediction of the vertical time series with the three ML approaches shows the precision in the range of 4–7 mm over the future 24- month period. The results also indicate the relative importance of different physical features causing the displacements of each site. Overall, ML approaches demonstrate better performance and effectiveness in modelling and prediction of GNSS time series, thus impacting maintenance of geodetic reference frames, geodynamics, geophysics, and crustal deformation analysis. Numéro de notice : A2022-737 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-022-01662-5 Date de publication en ligne : 27/09/2022 En ligne : https://doi.org/10.1007/s00190-022-01662-5 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=101709 An efficient method to compensate receiver clock jumps in real-time precise point positioning
An efficient method to compensate receiver clock jumps in real-time precise point positioning [Article/Communication] / Shaoguang Xu, Auteur ; Jialu Long, Auteur ; Jinling Wang, Auteur ; et al., Auteur . - 2022 . - n° 5222.bibliographieLangues : Anglais (eng)in Remote sensing > vol 14 n° 20 (October-2 2022) . - n° 5222Descripteur : [Vedettes matières IGN] Géodésie spatiale[Termes IGN] ambiguïté entière[Termes IGN] décalage d'horloge[Termes IGN] erreur de positionnement[Termes IGN] glissement de cycle[Termes IGN] horloge du récepteur[Termes IGN] phase[Termes IGN] positionnement cinématique en temps réel[Termes IGN] positionnement par GNSS[Termes IGN] positionnement ponctuel précis[Termes IGN] retard troposphérique zénithal[Termes IGN] temps réel Résumé : (auteur) In global navigation satellite systems (GNSSs)-based positioning, user receiver clock jump is a common phenomenon on the low-cost receiver clocks and can break the continuity of observation time tag, carrier phase and pseudo range. The discontinuity may affect precise point positioning-related parameter estimation, including receiver clock error, position, troposphere and ionosphere parameters. It is important to note that these parameters can be used for timing, positioning, atmospheric inversion and so on. In response to this problem, the receiver clock jumps are divided into two types. The first one can be expressed by the carrier phase and pseudo range having the same scale jump, and the second one is that they are having different scale jumps. For the first type, if a small priori variance of receiver clock error is provided, it can affect the accuracy of ionospheric delay estimation both in static and kinematic mode, while in the latter mode, it also affects position estimation. However, if large process noise is provided, numerical problems may arise since other parameters’ process noises are usually small, it is proposed to use the single point positioning with pseudo ranges to provide a priori value of receiver clock error, and an empiric value is assigned to its prior variance, this handle can avoid the above problems. For the second type, instead of compensating so many raw observations in the traditional methods, it is proposed to compensate the ambiguities at the clock jump epochs only in a new method. The new method corrects the Melbourne–Wubbena (MW) combination firstly in order to avoid the misjudging of cycle slips for current epoch, and the second step is to compensate the corresponding ambiguities, then, after Kalman filtering, the MW and its mean should be corrected back in order to avoid the misjudging of cycle slips at the next epoch. This approach has the advantage of handling the clock jump epoch-wise and can avoid correcting the rest of the observations as the traditional methods used to. With the numerical validation examples both in static and kinematic modes, it shows the new method is simple but efficient for real time precise point positioning (PPP). Numéro de notice : A2022-792 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.3390/rs14205222 Date de publication en ligne : 19/10/2022 En ligne : https://doi.org/10.3390/rs14205222 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=101909 Testing of new ionospheric models along the meridian 110° E over the Northern Hemisphere
Testing of new ionospheric models along the meridian 110° E over the Northern Hemisphere [Article/Communication] / Olga Maltseva, Auteur ; Artem Kharakhashyan, Auteur ; Tatyana Nikitenko, Auteur . - 2022 . - pp 544 - 553.bibliographieLangues : Anglais (eng)in Geodesy and Geodynamics > vol 13 n° 6 (November 2022) . - pp 544 - 553Descripteur : [Vedettes matières IGN] Géodésie spatiale[Termes IGN] hémisphère Nord[Termes IGN] méridien[Termes IGN] modèle ionosphérique[Termes IGN] teneur totale en électrons Résumé : (auteur) Despite the continuous improvement of the widely used empirical model international reference ionosphere (IRI), the recently appeared new models must be tested worldwide. Testing along the meridians has the advantage of dealing with the latitudinal dependent parameters. This paper uses new models of parameters foF2 (critical frequency), TEC (total electron content), and τ (equivalent slab thickness of the ionosphere), which are of great importance for evaluating the effects of space weather. IRI-Plas, NNT2F2, and NTSM models were tested using data from 6 ionosondes located along the meridian 110° E in March 2012. It is shown that the IRI-Plas model provides the closest values to experiment with respect to τ, while the NTSM model provides a rather limited reflection of the latitude dependence. Analyses of foF2(NNT2F2) have shown that, the NNT2F2 model provides good conformity with experimental values in this area, but it is very dependent on the TEC processing method. The latitudinal dependences of foF2 obtained with TEC and polynomial dependence τ(Appr) showed the presence of positive deviations from medians not only during disturbances but also quiet periods, longitudinally at the meridian. Numéro de notice : A2022-763 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.1016/j.geog.2022.06.002 Date de publication en ligne : 02/07/2022 En ligne : https://doi.org/10.1016/j.geog.2022.06.002 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=101783 - On the relation of GNSS phase center offsets and the terrestrial reference frame scale: a semi-analytical analysis [Article/Communication] / Oliver Montenbruck, Auteur ; Peter Steigenberger, Auteur ; Arturo Villiger, Auteur ; Paul Rebischung, Auteur . - 2022 . - n° 90.bibliographieLangues : Anglais (eng)in Journal of geodesy > vol 96 n° 11 (November 2022) . - n° 90
Descripteur : [Vedettes matières IGN] Géodésie spatiale[Termes IGN] antenne GNSS[Termes IGN] centre de phase[Termes IGN] décalage d'horloge[Termes IGN] hauteur (coordonnée)[Termes IGN] International Terrestrial Reference Frame[Termes IGN] orbitographie[Termes IGN] phase[Termes IGN] positionnement par GNSS[Termes IGN] retard troposphérique zénithal[Termes IGN] station GNSS Résumé : (auteur) Phase center offsets (PCOs) of global navigation satellites systems (GNSS) transmit antennas along the boresight axis introduce line-of-sight-dependent range changes in the modeling of GNSS observations that are strongly correlated with the estimated station heights. As a consequence, changes in the adopted PCOs impact the scale of GNSS-based realizations of the terrestrial reference frame (TRF). Vice versa, changes in the adopted TRF scale require corrections to the GNSS transmit antenna PCOs for consistent observation modeling. Early studies have determined an approximate value of α=−0.050 for the ratio of station height changes and satellite PCO changes in GPS orbit determination and phase center adjustment. However, this is mainly an empirical value and limited information is available on the actual PCO-scale relation and how it is influenced by other factors. In view of the recurring need to adjust the IGS antenna models to new ITRF scales, a semi-analytical model is developed to determine values of α for the four current GNSSs from first principles without a need for actual network data processing. Given the close coupling of satellite boresight angle and station zenith angle, satellite PCO changes are essentially compensated by a combination of station height, zenith troposphere delay, and receiver clock offset. As such, the value of α depends not only on the orbital altitude of the considered GNSS but also on the elevation-dependent distribution of GNSS observations and their weighting, as well as the elevation mask angle and the tropospheric mapping function. Based on the model, representative values of αGPS=−0.051, αGLO=−0.055, αGAL=−0.041, and αBDS-3=−0.046 are derived for GPS, GLONASS, Galileo, and BeiDou-3 at a 10∘ elevation cutoff angle. These values may vary by Δα≈0.003 depending on the specific model assumptions and data processing parameters in a precise orbit determination or precise point positioning. Likewise changes of about ±0.003 can be observed when varying the cutoff angle between 5∘ and 15∘. Numéro de notice : A2022-836 Affiliation des auteurs : UMR IPGP-Géod+Ext (2020- ) Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-022-01678-x Date de publication en ligne : 09/11/2022 En ligne : https://doi.org/10.1007/s00190-022-01678-x Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=102033 - Identifying spurious cycle slips based on iterative filtering under disturbed ionospheric conditions for undifferenced GNSS observations [Article/Communication] / Yan Xiang, Auteur ; Sijie Lyu, Auteur ; Wenxian Yu, Auteur . - 2022 . - pp 3582 - 3593.bibliographieLangues : Anglais (eng)in Advances in space research > vol 70 n° 11 (December 2022) . - pp 3582 - 3593
Descripteur : [Termes IGN] erreur de positionnement[Termes IGN] filtre[Termes IGN] glissement de cycle[Termes IGN] itération[Termes IGN] perturbation ionosphérique[Termes IGN] phase GNSS[Termes IGN] positionnement ponctuel précis[Vedettes matières IGN] Traitement de données GNSS Résumé : (auteur) The TurboEdit method is widely used to detect cycle slips on the global navigation satellite system (GNSS) carrier-phase measurements. However, it leads to an increasing number of false alarms in detecting cycle slips under disturbed ionospheric conditions. Besides, once the method detects a cycle slip at one satellite, it treats dual frequencies with cycle slips rather than at one frequency. Considering these two challenges, we developed a solution-based iterative filter detection method to reduce the number of spurious cycle slip detection under disturbed ionospheric conditions. The method initially assumes that there is no cycle slip at each frequency. We then estimate the solutions without cycle slips. A decision of exiting cycle slips is made by examining and comparing the two results solutions with or without cycle slips in terms of usable satellites, ambiguities, and residuals. The uncombined precise point positioning (PPP) during disturbed ionospheric conditions on 17 March 2015 at high latitude was studied to validate the proposed method. Results showed that the detected number of spurious cycle slips was reduced significantly. With fewer marked cycle slips, more stable and smoother positioning performance was achieved when fewer ambiguity parameters were reinitialized. Numéro de notice : A2022-861 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.1016/j.asr.2022.08.008 Date de publication en ligne : 08/08/2022 En ligne : https://doi.org/10.1016/j.asr.2022.08.008 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=102144 Multi-frequency simulation of ionospheric scintillation using a phase-screen model
Multi-frequency simulation of ionospheric scintillation using a phase-screen model [Article/Communication] / Fernando D. Nunes, Auteur ; Fernando M.G. Sousa, Auteur ; José M.V. Marçal, Auteur . - 2022 . - n° 545.bibliographieLangues : Anglais (eng)in Navigation : journal of the Institute of navigation > vol 69 n° 4 (Fall 2022) . - n° 545Descripteur : [Vedettes matières IGN] Géodésie spatiale[Termes IGN] amplitude[Termes IGN] correction ionosphérique[Termes IGN] fréquence multiple[Termes IGN] ionosphère[Termes IGN] méthode de Monte-Carlo[Termes IGN] phase[Termes IGN] scintillation[Termes IGN] série temporelle[Termes IGN] signal GNSS[Termes IGN] teneur totale en électrons Résumé : (auteur) A fast Monte Carlo technique to simulate equatorial ionospheric scintillation on global navigation satellite system signals is proposed. The algorithm uses a single-layer phase-screen model of the ionosphere and the scintillation is expressed as a Huygens-Fresnel integral (HFI). By assuming a specially-tailored random phase screen, the HFI can be expressed in closed form as a combination of Fresnel integrals. We statistically characterize the amplitude and phase computed by the HFI for different values of the scintillation index S4. Results for the L1, L2, and L5 bands were obtained and compared with real data, showing good agreement. Some of the advantages of the proposed technique are: (a) the amplitude and phase of the scintillation process are simultaneously obtained; (b) arbitrarily long ionospheric scintillation time series with pre-defined stationary characteristics are synthesized; and (c) several scintillation time series corresponding to different carrier frequencies are generated using a common phase-screen model. Numéro de notice : A2022-918 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.33012/navi.545 Date de publication en ligne : 18/06/2022 En ligne : https://doi.org/10.33012/navi.545 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=102446 Navigation and Ionosphere Characterization Using High-Frequency Signals: A Performance Analysis
Navigation and Ionosphere Characterization Using High-Frequency Signals: A Performance Analysis [Article/Communication] / Yoav Baumgarten, Auteur ; M.L. Psiaki, Auteur ; David L. Hysell, Auteur . - 2022 . - n° 546.bibliographieLangues : Anglais (eng)in Navigation : journal of the Institute of navigation > vol 69 n° 4 (Fall 2022) . - n° 546Descripteur : [Vedettes matières IGN] Traitement du signal[Termes IGN] algorithme de Gauss-Newton[Termes IGN] correction du signal[Termes IGN] correction ionosphérique[Termes IGN] matrice de covariance[Termes IGN] mesurage de phase[Termes IGN] modèle ionosphérique[Termes IGN] propagation du signal[Termes IGN] récepteur[Termes IGN] teneur verticale totale en électrons Résumé : (auteur) The performance of a proposed high-frequency (HF) navigation concept is analyzed using simulated data. The method relies on pseudorange and beat carrier-phase measurements of signals that propagate in the ionosphere along curved trajectories, where signals are refracted back downwards from the ionosphere. It has been demonstrated that the location of a receiver can be determined if several signals, broadcast from beacons at different locations, are received and processed at a user receiver. A challenge of determining exact signal paths is the uncertainty in the ionosphere’s electron density distribution. This is addressed by a batch filter that simultaneously estimates the receiver position along with corrections to a parametric model of the ionosphere. A previous paper developed the theory and batch filter for this concept. The present study examines its potential performance. Total horizontal position errors on the order of tens to hundreds of meters are achieved, depending on the case’s characteristics. Numéro de notice : A2022-919 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.33012/navi.546 Date de publication en ligne : 19/06/2022 En ligne : https://doi.org/10.33012/navi.546 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=102448 - Spatiotemporal accuracy evaluation and errors analysis of global VTEC maps using a simulation technique [Article/Communication] / Jian Lin, Auteur ; Xinxing Li, Auteur ; Shenfeng Gu, Auteur ; et al., Auteur . - 2023 . - n° 6.bibliographieLangues : Anglais (eng)in GPS solutions > vol 27 n° 1 (January 2023) . - n° 6
Descripteur : [Vedettes matières IGN] Géodésie spatiale[Termes IGN] données GPS[Termes IGN] harmonique sphérique[Termes IGN] modèle cartographique[Termes IGN] modèle ionosphérique[Termes IGN] phase[Termes IGN] rayonnement solaire[Termes IGN] simulation[Termes IGN] station GPS[Termes IGN] teneur verticale totale en électrons Résumé : (auteur) The computation of vertical total electron content (VTEC) maps has become an important issue gradually for the international GNSS service. Given the current literature reports, little research is involved in the quantitative analysis of each error of the VTEC map and the spatiotemporal characteristic of global VTEC accuracy. Based on the single layer model and sphere harmonic function, we propose an approach using simulated GPS data to comprehensively verify the accuracy of the VTEC map. The spatiotemporal characteristic of global VTEC accuracy and the errors induced by different processing steps, i.e., carrier phase to code leveling, mapping function (MF), DCB estimation and coefficient fitting, are analyzed and discussed in detail. In addition, the effect of solar activity on the accuracy of the global VTEC map, MF and DCB estimation has been discussed. The results suggest: First, it is found that the MF error at sunrise is more significant than that at sunset, and this important characteristic can be proven based on the analysis of theory and ionospheric radio occultation and VTEC measurements; second, the MF is the most significant error source in the VTEC processing for regions with dense and homogeneous distributed GPS stations, e.g., North America and Europe. The VTEC accuracy in these regions can be improved by 100% with the satellite elevation cutoff angle increasing from 12° to 30°; finally, compared with the global VTEC accuracy using 350 GPS stations observations, the accuracy is improved by 306% based on the double GPS stations with even distribution. Numéro de notice : A2023-002 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s10291-022-01343-y Date de publication en ligne : 13/10/2022 En ligne : https://doi.org/10.1007/s10291-022-01343-y Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=101871 - Establishing a high-precision real-time ZTD model of China with GPS and ERA5 historical data and its application in PPP [Article/Communication] / Pengfei Xia, Auteur ; Mengxiang Tong, Auteur ; Shirong Ye, Auteur ; et al., Auteur . - 2023 . - n° 2.bibliographieLangues : Anglais (eng)in GPS solutions > vol 27 n° 1 (January 2023) . - n° 2
Descripteur : [Vedettes matières IGN] Géodésie spatiale[Termes IGN] Chine[Termes IGN] correction troposphérique[Termes IGN] données météorologiques[Termes IGN] grille[Termes IGN] positionnement ponctuel précis[Termes IGN] retard troposphérique zénithal[Termes IGN] série de Fourier[Termes IGN] série temporelle[Termes IGN] station GNSS[Termes IGN] temps de convergence[Termes IGN] temps réel[Termes IGN] variation diurne Résumé : (auteur) A high-precision real-time troposphere model is constructed by combining ground-based GNSS observation data and the latest European Centre for Medium-Range Weather Forecasts (ECMWF) reanalysis (ERA5). First, the zenith tropospheric delay (ZTD) is extracted in real time with high accuracy by combining the data of more than 500 GNSS stations in the Crustal Movement Observation Network of China (CMONOC) and national reference station network (NRSN); second, a grid model of the elevation normalization model (ENM) in China using ERA5 data is constructed, which takes into account the annual, semiannual and daily cycles. The ZTD estimated by GNSS stations at different heights based on precise point positioning (PPP) is normalized to a uniform height based on ENM; in addition, the optimal smoothing factors of the Gauss distance weighting function in different seasons are determined based on ERA5, which contributes to improved accuracy of ZTD interpolated from GNSS-derived ZTD to ZTD at grid points; finally, a real-time 1° × 1°ZTD grid model of China is created; the broadcast interval is extended to 6 min from few seconds. The new ZTD model has been evaluated using the data of 15 GNSS stations in China in 2020. The test results show that the new ZTD model deviates from the reference value with a mean value better than − 0.09 cm and RMSE, better than 1.44 cm compared with the ZTD estimated by post-processing GNSS, while the mean value of the deviation is -0.13 cm, and the RMSE is approximately 3.11 cm compared with radiosonde-derived ZTD. The new ZTD grid model can be used to enhance GNSS/PPP. Two weeks of GNSS observations, one week in winter and another in summer, were randomly collected for PPP processing. The statistical results show the convergence time in the vertical directions is shortened by 37.4% and 38.6% at the 95% and 68% confidence levels after ZTD constraints are applied to the float PPP solution, respectively. Numéro de notice : A2023-004 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s10291-022-01338-9 Date de publication en ligne : 07/10/2022 En ligne : https://doi.org/10.1007/s10291-022-01338-9 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=101874 - Parameterisation of the GNSS troposphere tomography domain with optimisation of the nodes’ distribution [Article/Communication] / Estera Trzcina, Auteur ; Witold Rohm, Auteur ; Kamil Smolak, Auteur . - 2023 . - n° 2.bibliographieLangues : Anglais (eng)in Journal of geodesy > vol 97 n° 1 (January 2023) . - n° 2
Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale[Termes IGN] données GNSS[Termes IGN] interpolation bilinéaire[Termes IGN] modèle météorologique[Termes IGN] optimisation (mathématiques)[Termes IGN] radiosondage[Termes IGN] récepteur GNSS[Termes IGN] retard troposphérique[Termes IGN] retard troposphérique zénithal[Termes IGN] système de grille globale discrète[Termes IGN] teneur en vapeur d'eau[Termes IGN] tomographie[Termes IGN] troposphère Résumé : (auteur) Water vapour is a highly variable constituent of the troposphere; thus, its high-resolution measurements are of great importance to weather prediction systems. The Global Navigation Satellite Systems (GNSS) are operationally used in the estimation of the tropospheric state and assimilation of the results into the weather models. One of the GNSS techniques of troposphere sensing is tomography which provides 3-D fields of wet refractivity. The tomographic results have been successfully assimilated into the numerical weather models, showing the great potential of this technique. The GNSS tomography can be based on two different approaches to the parameterisation of the model’s domain, i.e. block (voxel-based) or grid (node-based) approach. Regardless of the parameterisation approach, the tomographic domain should be discretised, which is usually performed in a regular manner, with a grid resolution depending on the mean distance between the GNSS receivers. In this work, we propose a new parameterisation approach based on the optimisation of the tomographic nodes’ location, taking into account the non-uniform distribution of the GNSS information in the troposphere. The experiment was performed using a dense network of 16 low-cost multi-GNSS receivers located in Wrocław and its suburbs, with a mean distance of 3 km. Cross-validation of four different parameterisation approaches is presented. The validation is performed based on the Weather Research and Forecasting model as well as radiosonde observations. The new approach improves the results of wet refractivity estimation by 0.5–2 ppm in terms of RMSE, especially for altitudes of 0.5–2.0 km. Numéro de notice : A2023-044 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : https://doi.org/10.1007/s00190-022-01691-0 Date de publication en ligne : 30/12/2022 En ligne : https://doi.org/10.1007/s00190-022-01691-0 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=102343 - Precipitation frequency in Med-CORDEX and EURO-CORDEX ensembles from 0.44° to convection-permitting resolution: impact of model resolution and convection representation [Article/Communication] / Minh Ha-Truong, Auteur ; Sophie Bastin, Auteur ; Philippe Drobinski, Auteur ; Lluis Fita, Auteur ; Jan Polcher, Auteur ; Olivier Bock, Auteur ; et al., Auteur . - 2023.bibliographie All authors gratefully acknowledge the WCRP-CORDEX-FPS on Convective phenomena at high resolution over Europe and the Mediterranean (FPSCONVALP- 3) and the research data exchange infrastructure and services provided by the Jülich Supercomputing Centre, Germany, as part of the Helmholtz Data Federation initiative. To process the data, this study benefited from the IPSL mesocenter ESPRI facility which is supported by CNRS, UPMC, Labex L-IPSL, CNES and EcolePolytechnique, and received funding from the HORIZON 2020 EUCP (European Climate Prediction System) project (https://www.eucp-project.eu, grant agreement No. 776613).Langues : Anglais (eng)in Climate Dynamics > vol 60 n° inconnu (2023)
Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale[Termes IGN] bassin méditerranéen[Termes IGN] convection[Termes IGN] données météorologiques[Termes IGN] Europe (géographie politique)[Termes IGN] modèle atmosphérique[Termes IGN] orographie[Termes IGN] précipitation[Termes IGN] teneur intégrée en vapeur d'eau Résumé : (auteur) Recent studies using convection-permitting (CP) climate simulations have demonstrated a step-change in the representation of heavy rainfall and rainfall characteristics (frequency-intensity) compared to coarser resolution Global and Regional climate models. The goal of this study is to better understand what explains the weaker frequency of precipitation in the CP ensemble by assessing the triggering process of precipitation in the different ensembles of regional climate simulations available over Europe. We focus on the statistical relationship between tropospheric temperature, humidity and precipitation to understand how the frequency of precipitation over Europe and the Mediterranean is impacted by model resolution and the representation of convection (parameterized vs. explicit). We employ a multi-model data-set with three different resolutions (0.44°, 0.11° and 0.0275°) produced in the context of the MED-CORDEX, EURO-CORDEX and the CORDEX Flagship Pilot Study "Convective Phenomena over Europe and the Mediterranean" (FPSCONV). The multi-variate approach is applied to all model ensembles, and to several surface stations where the integrated water vapor (IWV) is derived from Global Positioning System (GPS) measurements. The results show that all model ensembles capture the temperature dependence of the critical value of IWV (IWVcv), above which an increase in precipitation frequency occurs, but the differences between the models in terms of the value of IWVcv, and the probability of its being exceeded, can be large at higher temperatures. The lower frequency of precipitation in convection-permitting simulations is not only explained by higher temperatures but also by a higher IWVcv necessary to trigger precipitation at similar temperatures, and a lower probability to exceed this critical value. The spread between models in simulating IWVcv and the probability of exceeding IWVcv is reduced over land in the ensemble of models with explicit convection, especially at high temperatures, when the convective fraction of total precipitation becomes more important and the influence of the representation of entrainment in models thus becomes more important. Over lowlands, both model resolution and convection representation affect precipitation triggering while over mountainous areas, resolution has the highest impact due to orography-induced triggering processes. Over the sea, since lifting is produced by large-scale convergence, the probability to exceed IWVcv does not depend on temperature, and the model resolution does not have a clear impact on the results. Numéro de notice : A2023-072 Affiliation des auteurs : UMR IPGP-Géod+Ext (2020- ) Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00382-022-06594-6 Date de publication en ligne : 29/12/2022 En ligne : https://doi.org/10.1007/s00382-022-06594-6 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=102360 - The ULR-repro3 GPS data reanalysis and its estimates of vertical land motion at tide gauges for sea level science [Article/Communication] / Médéric Gravelle, Auteur ; Guy Wöppelmann, Auteur ; Kevin Gobron, Auteur ; Zuheir Altamimi, Auteur ; Mikaël Guichard, Auteur ; Thomas Herring, Auteur ; Paul Rebischung, Auteur . - 2023.bibliographieLangues : Anglais (eng)in Earth System Science Data > vol 15 n° inconnu (2023)
Résumé : (auteur) A new reanalysis of GNSS data at or near tide gauges worldwide was produced by the university of La Rochelle (ULR) group within the 3rd International GNSS Service (IGS) reprocessing campaign (repro3). The new solution, called ULR-repro3, complies with the IGS standards adopted for repro3, implementing advances in data modelling and corrections since the previous reanalysis campaign, and extending the average record length by about 7 years. The results presented here focus on the main products of interest for sea level science, that is, the station position time series and associated velocities on the vertical component at tide gauges. These products are useful to estimate accurate vertical land motion at the coast and supplement data from satellite altimetry or tide gauges for an improved understanding of sea level changes and their impacts along coastal areas. To provide realistic velocity uncertainty estimates, the noise content in the position time series was investigated considering the impact of non-tidal atmospheric loading. Overall, the ULR-repro3 position time series show reduced white noise and power-law amplitudes and station velocity uncertainties compared to the previous reanalysis. The products are available via SONEL (https://doi.org/10.26166/sonel_ulr7a; Gravelle et al., 2022). Numéro de notice : A2023-079 Affiliation des auteurs : UMR IPGP-Géod+Ext (2020- ) Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.5194/essd-2022-235 En ligne : https://doi.org/10.5194/essd-2022-235 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=102521
