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Alerte-GNSS & météo

Utilisation des réseaux de capteurs Géocubes pour la mesure de déformation des volcans en temps réel par GNSS (2018)

Utilisation des réseaux de capteurs Géocubes pour la mesure de déformation des volcans en temps réel par GNSS [Thèse/HDR] / Mohamed-Amjad Lasri, Auteur ; Pierre Briole, Directeur de thèse ; Christian Thom, Directeur de thèse . - Paris : Université Paris Sciences et Lettres, 2018 . - 122 p. ; 21 x 30 cm.bibliographie Thèse de doctorat de l’Université de recherche Paris Sciences et Lettres, PSL Research UniversityLangues : Français (fre)

Descripteur :	[Vedettes matières IGN] Applications de géodésie spatiale[Termes IGN] déformation de la croute terrestre[Termes IGN] Etna (volcan)[Termes IGN] filtre de Kalman[Termes IGN] Géocube[Termes IGN] image radar moirée[Termes IGN] image Sentinel-SAR[Termes IGN] interféromètrie par radar à antenne synthétique[Termes IGN] positionnement par GNSS[Termes IGN] réseau géodésique local[Termes IGN] retard troposphérique[Termes IGN] surveillance géologique[Termes IGN] volcanologie
Résumé :	(auteur) Le système Géocube est un réseau de capteurs GPS conçu et développé par le Laboratoire d'OptoÉléctronique de Métrologie et d'Instrumentation (LOEMI) de l'Institut National de l'Information Géographique et Forestière (IGN) et maintenu par le même laboratoire et l'entreprise Ophelia- Sensors qui s'occupe de son industrialisation. Il a comme objectif de mesurer les déformations du sol avec une précision millimétrique. Ce réseau de capteurs a la particularité d'être à la fois très peu énergivore, d’un faible coût de revient, simple d’installation et d’utilisation. Il est donc bien adapté à l’usage dans un environnement difficile, comme les volcans. Ce système a déjà été testé avec succès lors d’une précédente thèse sur le glacier d’Argentière et sur un glissement de terrain proche de Super-Sauze en France. La première partie de cette thèse porte sur l’optimisation du système de calcul du Géocube pour l'adapter à des réseaux de tailles plus importantes horizontalement et verticalement en vue de son utilisation dans un contexte volcanique. Cela passe, d’abord, par l’intégration d’une stratégie pour l’estimation du biais troposphérique dans le filtre de Kalman qui constitue le coeur du logiciel de calcul du Géocube. Cette amélioration est ensuite validée en utilisant les données de quelques réseaux GNSS permanents nationaux et internationaux. La deuxième partie consiste à étudier l’apport d’un réseau dense de Géocubes à l’étude du volcanisme à travers une expérience conduite sur le flanc sud-est de l’Etna, où cinq Géocubes ont été déployés entre le 12 Juillet 2016 et le 10 Juillet 2017. Les résultats obtenus et les enseignements tirés de cette expérimentation sont discutés et analysés. Enfin, nous validons les résultats obtenus avec les Géocubes en appliquant une technique PSI (Persistent Scatterer InSAR) sur des interférogrammes RADAR calculés à partir des données des satellites Sentinel-1A/B et qui couvrent la période de déploiement des Géocubes sur l’Etna. Ces deux méthodes (GPS et RADAR) se sont avérées complémentaires puisque le RADAR apporte la densité spatiale des mesures et le système Géocube la précision et la continuité temporelle.
Note de contenu :	1- Introduction 2- Mesure de déformations de surface des volcans 3- Technique de mesure de déformations sub-centimètriques en temps réel adaptée à la surveillance des volcans basée sur un réseau de Géo-cubes 4- Surveillance des déformations du flanc sud-est de l’Etna en utilisant un réseau de Géocubes et l’InSAR 5- Bilan et perspectives
Numéro de notice :	17676
Affiliation des auteurs :	LASTIG LOEMI (2012-2019)
Thématique :	IMAGERIE/POSITIONNEMENT
Nature :	Thèse française
Note de thèse :	thèse de doctorat : Sciences de la Terre et de l'environnement : PSL : 2018
Organisme de stage :	LOEMI (IGN) & Laboratoire de géologie de l'ENS & Kylia
nature-HAL :	Thèse
En ligne :	https://tel.archives-ouvertes.fr/tel-02426022/document
Format de la ressource électronique :	URL
Permalink :	https://documentation.ensg.eu/index.php?lvl=notice_display&id=98012

Does long-term GPS in the Western Alps finally confirm earthquake mechanisms?

Does long-term GPS in the Western Alps finally confirm earthquake mechanisms? [Article/Communication] / Andrea Walpersdorf, Auteur ; L. Pinget, Auteur ; P. Vernant, Auteur ; C. Sue, Auteur ; A. Deprez, Auteur ; et al., Auteur ; Olivier Bock, Auteur ; Thierry Duquesnoy, Auteur ; Romain Fagès, Auteur ; Bruno Garayt, Auteur ; Elise-Rachel Mathis, Auteur ; Thierry Person, Auteur ; Sébastien Saur, Auteur . - 2018 . - pp 3721 - 3737.bibliographieLangues : Anglais (eng)in Tectonics > vol 37 n° 10 (October 2018) . - pp 3721 - 3737

Descripteur :	[Vedettes matières IGN] Applications de géodésie spatiale[Termes IGN] Alpes occidentales[Termes IGN] coordonnées GPS[Termes IGN] séisme[Termes IGN] série temporelle
Résumé :	(auteur) The availability of GPS survey data spanning 22 years, along with several independent velocity solutions including up to 16 years of permanent GPS data, presents a unique opportunity to search for persistent (and thus reliable) deformation patterns in the Western Alps, which in turn allow a reinterpretation of the active tectonics of this region. While GPS velocities are still too uncertain to be interpreted on an individual basis, the analysis of range-perpendicular GPS velocity profiles clearly highlights zones of extension in the center of the belt (15.3 to 3.1 nanostrain/year from north to south), with shortening in the forelands. The contrasting geodetic deformation pattern is coherent with earthquake focal mechanisms and related strain/stress patterns over the entire Western Alps. The GPS results finally provide a reliable and robust quantification of the regional strain rates. The observed vertical motions of 2.0 to 0.5 mm/year of uplift from north to south in the core of the Western Alps is interpreted to result from buoyancy forces related to postglacial rebound, erosional unloading, and/or viscosity anomalies in the crustal and lithospheric root. Spatial decorrelation between vertical and horizontal (seismicity related) deformation calls for a combination of processes to explain the complex present-day dynamics of the Western Alps.
Numéro de notice :	A2018-681
Affiliation des auteurs :	IGN+Ext (2012-2019)
Thématique :	POSITIONNEMENT
Nature :	Article
nature-HAL :	ArtAvecCL-RevueIntern
DOI :	10.1029/2018TC005054
Date de publication en ligne :	03/09/2018
En ligne :	https://doi.org/10.1029/2018TC005054
Format de la ressource électronique :	URL article
Permalink :	https://documentation.ensg.eu/index.php?lvl=notice_display&id=98132

Satellites missions and technologies for geosciences (2020)

Satellites missions and technologies for geosciences [Monographie] / Vladislav Demyanov, Éditeur scientifique ; Jonathan Becedas, Éditeur scientifique . - London [UK] : IntechOpen, 2020 . - 182 p. ; 16 x 24 cm.ISBN : 978-1-78985-301-8BibliographieLangues : Anglais (eng)

Descripteur :	[Vedettes matières IGN] Technologies spatiales[Termes IGN] données GNSS[Termes IGN] géodésie spatiale[Termes IGN] mission spatiale[Termes IGN] nanosatellite[Termes IGN] observation de la Terre[Termes IGN] perturbation ionosphérique[Termes IGN] signal GPS[Termes IGN] système de navigation[Termes IGN] technologies spatiales[Termes IGN] télédétection spatiale[Termes IGN] temps réel[Termes IGN] teneur totale en électrons[Termes IGN] traitement du signal
Résumé :	(Editeur) Being a vital modern technology, satellite systems for navigation, telecommunication, and geosciences have developed rapidly in the last 25 years. Modern satellite technologies have become a base of our civilization and support our day-to-day activity in both practice and geosciences. This book is devoted to GNSS-remote sensing for ionosphere research, modeling and mitigation techniques to diminish the ionosphere and multipath impacts on GNSS, and survey of the modern satellite missions and technologies. We hope that the experts’ opinions presented in the book will be interesting for the research community and students in the area of satellites and space missions as well as in engineering and geoscience research.
Note de contenu :	1. GNSS High-Rate Data and the Efficiency of Ionospheric Scintillation Indices 2. The Influence of the Lower Ionospheric Disturbances on the Operating Conditions of Navigation Satellite Systems 3. Real-Time Monitoring of Ionospheric Irregularities and TEC Perturbations 4. GPS Signal Multipath Error Mitigation Technique 5. The Impact of Space Radiation Environment on Satellites Operation in Near-Earth Space 6. Ionospheric Scintillation Modeling Needs and Tricks 7. Earth Observation Technologies: Low-End-Market Disruptive Innovation 8. A Survey on Small Satellite Technologies and Space Missions for Geodetic Applications 9. Nanosatellites and Applications to Commercial and Scientific Missions
Numéro de notice :	26672
Affiliation des auteurs :	non IGN
Thématique :	IMAGERIE/POSITIONNEMENT
Nature :	Recueil / ouvrage collectif
DOI :	10.5772/intechopen.83246
Date de publication en ligne :	22/07/2020
En ligne :	https://doi.org/10.5772/intechopen.83246
Format de la ressource électronique :	URL
Permalink :	https://documentation.ensg.eu/index.php?lvl=notice_display&id=98951

Spatial variability in environmental science (2020)

Spatial variability in environmental science : patterns, processes, and analyses [Monographie] / John P. Tiefenbacher, Éditeur scientifique ; Davod Poreh, Éditeur scientifique . - London [UK] : IntechOpen, 2020.ISBN : 978-1-83962-461-2BibliographieLangues : Anglais (eng)

Descripteur :	[Vedettes matières IGN] Applications de télédétection[Termes IGN] aménagement paysager[Termes IGN] aquaculture[Termes IGN] azote[Termes IGN] détection du bâti[Termes IGN] données environnementales[Termes IGN] données GNSS[Termes IGN] données lidar[Termes IGN] données localisées 3D[Termes IGN] données spatiotemporelles[Termes IGN] écologie forestière[Termes IGN] forêt[Termes IGN] ilot thermique urbain[Termes IGN] littoral[Termes IGN] photogrammétrie numérique[Termes IGN] photographie aérienne[Termes IGN] pollution atmosphérique[Termes IGN] soufre[Termes IGN] surveillance météorologique[Termes IGN] vent
Résumé :	(Editeur) This book includes eight studies that examine the issue of spatial variability in four areas of the environmental sciences – atmospheric science, geological science, biological science, and landscape science. The topics range from monitoring of wind, the urban heat island, and atmospheric pollution, to coastal geomorphology, landscape planning and forest ecology, the problem of introduced species to regional ecologies, and a technique to improve the identification of human constructions in semi-natural landscapes. A small volume can only offer a small glimpse at the activities of scientists and insights into environmental science, but the array of papers herein offers a unique view of the current scholarship.
Note de contenu :	1. Coherent Doppler Lidar for Wind Sensing 2. Low-Key Stationary and Mobile Tools for Probing the Atmospheric UHI Effect 3. Mapping and Estimation of Nitrogen and Sulfur Atmospheric Deposition Fluxes in Central Region of the Mexican Bajio 4. Monitoring Storm Impacts on Sandy Coastlines with UAVs 5. Recent Advances in Coastal Survey Techniques: From GNSS to LiDAR and Digital Photogrammetry - Examples on the Northern Coast of France 6. Spatial and Temporal Variability Regarding Forest: From Tree to the Landscape 7. Ecological and Social Impacts of Aquacultural Introduction to Philippines Waters of Pacific Whiteleg Shrimp Penaeus vannamei 8. High-Resolution Object-Based Building Extraction Using PCA of LiDAR nDSM and Aerial Photos
Numéro de notice :	26692
Affiliation des auteurs :	non IGN
Thématique :	FORET/IMAGERIE/URBANISME
Nature :	Recueil / ouvrage collectif
DOI :	10.5772/intechopen.87655
Date de publication en ligne :	21/10/2020
En ligne :	https://doi.org/10.5772/intechopen.87655
Format de la ressource électronique :	URL
Permalink :	https://documentation.ensg.eu/index.php?lvl=notice_display&id=99032

Remote sensing of snow and its applications (2021)

Remote sensing of snow and its applications [Monographie] / Ali Nadir Arslan, Éditeur scientifique ; Zuhal Akyurek, Éditeur scientifique . - Bâle [Suisse] : Multidisciplinary Digital Publishing Institute MDPI, 2021 . - 190 p. ; 21 x 30 cm.ISBN : 978-3-0365-0071-3bibliographieLangues : Anglais (eng)

Descripteur :	[Vedettes matières IGN] Applications de télédétection[Termes IGN] bilan de masse[Termes IGN] Canada[Termes IGN] glacier[Termes IGN] image radar moirée[Termes IGN] image Sentinel-MSI[Termes IGN] image Sentinel-SAR[Termes IGN] image Terra-MODIS[Termes IGN] manteau neigeux[Termes IGN] modèle hydrographique[Termes IGN] modèle météorologique[Termes IGN] Mongolie[Termes IGN] neige[Termes IGN] réflectance
Résumé :	(éditeur) The reprint book of the "Remote Sensing of Snow and Its Applications" Special Issue provides recent studies on all aspects of remote sensing of snow, from retrieving the data to the application. These studies mainly address the following: (a) New opportunities (Copernicus Sentinels) and emerging remote sensing methods, (b) use of snow data in modeling, and (c) characterization of snowpack.
Note de contenu :	1- Special issue on remote sensing of snow and its applications 2- Cross-country assessment of H-SAF snow products by Sentinel-2 imagery validated against in-situ observations and webcam photography 3- Automated classification of terrestrial images: The contribution to the remote sensing of snow cove 4- Multi-source based spatio-temporal distribution of snow in a semi-arid headwater catchment of Northern Mongolia 5- Discriminating wet snow and firn for alpine glaciers using Sentinel-1 data: A case study at Rofental, Austria 6- Review of snow data assimilation methods for hydrological, land surface, meteorological and climate models: results from a COST HarmoSnow survey 7- Generating observation-based snow depletion curves for use in snow cover data assimilation 8- Advances in snow hydrology using a combined approach of GNSS in situ stations, hydrological modelling and Earth observation - A case study in Canada 9- Analysis of qualitySpec trek reflectance from vertical profiles of taiga snowpack 10- Geometric versus anemometric surface roughness for a shallow accumulating snowpack
Numéro de notice :	28386
Affiliation des auteurs :	non IGN
Thématique :	IMAGERIE
Nature :	Recueil / ouvrage collectif
DOI :	10.3390/books978-3-0365-0071-3
En ligne :	https://doi.org/10.3390/books978-3-0365-0071-3
Format de la ressource électronique :	URL
Permalink :	https://documentation.ensg.eu/index.php?lvl=notice_display&id=98623

Remote sensing by satellite gravimetry (2021)

Remote sensing by satellite gravimetry [Monographie] / Thomas Gruber, Éditeur scientifique ; Annette Eicker, Éditeur scientifique ; Frank Flechtner, Éditeur scientifique . - Bâle [Suisse] : Multidisciplinary Digital Publishing Institute MDPI, 2021 . - 286 p. ; 16 x 24 cm.ISBN : 978-3-0365-0009-6bibliographieLangues : Anglais (eng)

Descripteur :	[Vedettes matières IGN] Géodésie physique[Termes IGN] bilan de masse[Termes IGN] CHAMP (satellite)[Termes IGN] champ de pesanteur terrestre[Termes IGN] données GOCE[Termes IGN] données GRACE[Termes IGN] géocentre[Termes IGN] gradient de gravitation[Termes IGN] gravimétrie spatiale[Termes IGN] nivellement par GPS[Termes IGN] orbitographie[Termes IGN] télémétrie laser sur satellite
Résumé :	(auteur) Over the last two decades, satellite gravimetry has become a new remote sensing technique that provides a detailed global picture of the physical structure of the Earth. With the CHAMP, GRACE, GOCE and GRACE Follow-On missions, mass distribution and mass transport in the Earth system can be systematically observed and monitored from space. A wide range of Earth science disciplines benefit from these data, enabling improvements in applied models, providing new insights into Earth system processes (e.g., monitoring the global water cycle, ice sheet and glacier melting or sea-level rise) or establishing new operational services. Long time series of mass transport data are needed to disentangle anthropogenic and natural sources of climate change impacts on the Earth system. In order to secure sustained observations on a long-term basis, space agencies and the Earth science community are currently planning future satellite gravimetry mission concepts to enable higher accuracy and better spatial and temporal resolution. This Special Issue provides examples of recent improvements in gravity observation techniques and data processing and analysis, applications in the fields of hydrology, glaciology and solid Earth based on satellite gravimetry data, as well as concepts of future satellite constellations for monitoring mass transport in the Earth system.
Note de contenu :	1- The GFZ GRACE RL06 monthly gravity field time series: Processing details and quality assessment 2- SLR, GRACE and swarm gravity field determination and combination 3- A new approach to Earth’s gravity field modeling using GPS-derived kinematic orbits and baselines 4- Improved estimates of geocenter variability from time-variable gravity and ocean model outputs 5- An assessment of the GOCE high-level processing facility (HPF) released global geopotential models with regional test results in Turkey 6- Next-generation gravity missions: Sino-European numerical simulation comparison exercise 7- Combination analysis of future polar-type gravity mission and GRACE follow-on 8- Gravity field recovery using high-precision, high–low inter-satellite links 9- High-resolution mass trends of the Antarctic ice sheet through a spectral combination of satellite gravimetry and radar altimetry observations 10- The rapid and steady mass loss of the Patagonian icefields throughout the GRACE era: 2002–2017 11- Downscaling GRACE TWSA data into high-resolution groundwater level anomaly using machine learning-based models in a glacial aquifer system 12- Hydrologic mass changes and their implications in Mediterranean-climate Turkey from GRACE measurements 13- GOCE-derived coseismic gravity gradient changes caused by the 2011 Tohoku-Oki earthquake
Numéro de notice :	28391
Affiliation des auteurs :	non IGN
Thématique :	POSITIONNEMENT
Nature :	Recueil / ouvrage collectif
DOI :	10.3390/books978-3-0365-0009-6
En ligne :	https://doi.org/10.3390/books978-3-0365-0009-6
Format de la ressource électronique :	URL
Permalink :	https://documentation.ensg.eu/index.php?lvl=notice_display&id=98720

A new segmentation method for the homogenisation of GNSS-derived IWV time-series (2021)

A new segmentation method for the homogenisation of GNSS-derived IWV time-series [Article/Communication] / Annarosa Quarello, Auteur ; Olivier Bock, Auteur ; Emilie Lebarbier, Auteur . - Saint-Mandé : Institut national de l'information géographique et forestière - IGN, 2021 . - 25 p.bibliographie Langues : Anglais (eng)

Descripteur :	[Vedettes matières IGN] Statistiques[Termes IGN] coordonnées GNSS[Termes IGN] erreur systématique[Termes IGN] programmation dynamique[Termes IGN] R (langage)[Termes IGN] segmentation[Termes IGN] série temporelle[Termes IGN] station permanente[Termes IGN] teneur intégrée en vapeur d'eau[Termes IGN] variance[Termes IGN] variation saisonnière
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 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 that remains the most efficient exact algorithm to estimate the change-point positions. The statistical performance of the method is assessed through numerical experiments. An application to a real data set of 120 global GNSS stations is presented. The method is implemented in the R package GNSSseg that will be available on the CRAN.
Numéro de notice :	P2021-007
Affiliation des auteurs :	UMR IPGP-Géod+Ext (2020- )
Thématique :	MATHEMATIQUE/POSITIONNEMENT
Nature :	Preprint
nature-HAL :	Préprint
DOI :	sans
En ligne :	https://arxiv.org/pdf/2005.04683.pdf
Format de la ressource électronique :	URL article
Permalink :	https://documentation.ensg.eu/index.php?lvl=notice_display&id=99326

Application of a multi-layer artificial neural network in a 3-D global electron density model using the long-term observations of COSMIC, Fengyun-3C, and Digisonde

Application of a multi-layer artificial neural network in a 3-D global electron density model using the long-term observations of COSMIC, Fengyun-3C, and Digisonde [Article/Communication] / Li Wang, Auteur ; Zhao Dongsheng ; Changyong He, Auteur ; et al., Auteur . - 2021 . - n° e2020SW002605.bibliographie The authors greatly appreciate the financial support from the National Natural Science Foundations of China (Grant No. 41730109, 41804013), the Natural Science Foundation of Jiangsu Province (Grant No. BK20200646, BK20200664), the Fundamental Re-search Funds for the Central Universi-ties (Grant No. 2020QN31, 2020QN30), the Project funded by China Postdoc-toral Science Foundation (Grant No. 2020M671645), the Open Fund of Key Laboratory for Synergistic Prevention of Water and Soil Environmental Pollution (Grant No. KLSPWSEP-A06), A Project Funded by the Priority Academic Pro-gram Development of Jiangsu Higher Education Institutions (Surveying and Mapping).Langues : Anglais (eng)in Space weather > vol 19 n° 3 (March 2021) . - n° e2020SW002605

Descripteur :	[Vedettes matières IGN] Géodésie spatiale[Termes IGN] image Formosat/COSMIC[Termes IGN] modèle ionosphérique[Termes IGN] Perceptron multicouche[Termes IGN] réseau neuronal artificiel[Termes IGN] teneur totale en électrons[Termes IGN] variation saisonnière
Résumé :	(auteur) The ionosphere plays an important role in satellite navigation, radio communication, and space weather prediction. However, it is still a challenging mission to develop a model with high predictability that captures the horizontal-vertical features of ionospheric electrodynamics. In this study, multiple observations during 2005–2019 from space-borne global navigation satellite system (GNSS) radio occultation (RO) systems (COSMIC and FY-3C) and the Digisonde Global Ionosphere Radio Observatory are utilized to develop a completely global ionospheric three-dimensional electron density model based on an artificial neural network, namely ANN-TDD. The correlation coefficients of the predicted profiles all exceed 0.96 for the training, validation and test datasets, and the minimum root-mean-square error of the predicted residuals is 7.8 × 104 el/cm3. Under quiet space weather, the predicted accuracy of the ANN-TDD is 30%–60% higher than the IRI-2016 at the Millstone Hill and Jicamarca incoherent scatter radars. However, the ANN-TDD is less capable of predicting ionospheric dynamic evolution under severe geomagnetic storms compared to the IRI-2016 with the STORM option activated. Additionally, the ANN-TDD successfully reproduces the large-scale horizontal-vertical ionospheric electrodynamic features, including seasonal variation and hemispheric asymmetries. These features agree well with the structure revealed by the RO profiles derived from the FORMOSAT/COSMIC-2 mission. Furthermore, the ANN-TDD successfully captures the prominent regional ionospheric patterns, including the equatorial ionization anomaly, Weddell Sea anomaly and mid-latitude summer nighttime anomaly. The new model is expected to play an important role in the application of GNSS navigation and in the explanation of the physical mechanisms involved.
Numéro de notice :	A2021-504
Affiliation des auteurs :	ENSG+Ext (2020- )
Thématique :	POSITIONNEMENT
Nature :	Article
nature-HAL :	ArtAvecCL-RevueIntern
DOI :	10.1029/2020SW002605
Date de publication en ligne :	10/03/2021
En ligne :	https://doi.org/10.1029/2020SW002605
Format de la ressource électronique :	URL article
Permalink :	https://documentation.ensg.eu/index.php?lvl=notice_display&id=99369

Scalable deep learning to identify brick kilns and aid regulatory capacity

Scalable deep learning to identify brick kilns and aid regulatory capacity [Article/Communication] / Jihyeon Lee, Auteur ; Nina R. Brooks, Auteur ; Fahim Tajwar, Auteur ; et al., Auteur . - 2021 . - n° e2018863118.bibliographieLangues : Anglais (eng)in Proceedings of the National Academy of Sciences of the United States of America PNAS > vol 118 n° 17 [27/04/2021] . - n° e2018863118

Descripteur :	[Vedettes matières IGN] Traitement d'image optique[Termes IGN] apprentissage profond[Termes IGN] Bangladesh[Termes IGN] chaîne de traitement[Termes IGN] image Worldview[Termes IGN] pollution atmosphérique
Mots-clés libres :	briqueterie
Résumé :	(auteur) Improving compliance with environmental regulations is critical for promoting clean environments and healthy populations. In South Asia, brick manufacturing is a major source of pollution but is dominated by small-scale, informal producers who are difficult to monitor and regulate—a common challenge in low-income settings. We demonstrate a low-cost, scalable approach for locating brick kilns in high-resolution satellite imagery from Bangladesh. Our approach identifies kilns with 94.2% accuracy and 88.7% precision and extracts the precise GPS coordinates of every brick kiln across Bangladesh. Using these estimates, we show that at least 12% of the population of Bangladesh (>18 million people) live within 1 km of a kiln and that 77% and 9% of kilns are (illegally) within 1 km of schools and health facilities, respectively. Finally, we show how kilns contribute up to 20.4 μg/m3 of PM2.5 (particulate matter of a diameter less than 2.5 μm) in Dhaka when the wind blows from an unfavorable direction. We document inaccuracies and potential bias with respect to local regulations in the government data. Our approach demonstrates how machine learning and Earth observation can be combined to better understand the extent and implications of regulatory compliance in informal industry.
Numéro de notice :	A2021-793
Affiliation des auteurs :	non IGN
Thématique :	IMAGERIE/INFORMATIQUE
Nature :	Article
DOI :	10.1073/pnas.2018863118
En ligne :	https://doi.org/10.1073/pnas.2018863118
Format de la ressource électronique :	URL article
Permalink :	https://documentation.ensg.eu/index.php?lvl=notice_display&id=99084

Impact of different sampling rates on precise point positioning performance using online processing service

Impact of different sampling rates on precise point positioning performance using online processing service [Article/Communication] / Serdar Erol, Auteur ; Reha Metin Alkan, Auteur ; I. Murat Ozulu, Auteur ; et al., Auteur . - 2021 . - pp 302 - 312.bibliographieLangues : Anglais (eng)in Geo-spatial Information Science > vol 24 n° 2 (June 2021) . - pp 302 - 312

Descripteur :	[Vedettes matières IGN] Navigation et positionnement[Termes IGN] données GNSS[Termes IGN] format RINEX[Termes IGN] instrumentation Trimble[Termes IGN] intervalle de confiance[Termes IGN] phase 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] réalité de terrain[Termes IGN] retard troposphérique zénithal[Termes IGN] taux d'échantillonnage[Termes IGN] trajet multiple[Termes IGN] Turquie
Résumé :	(auteur) In this study, the effect of different sampling rates (i.e. observation recording interval) on the Precise Point Positioning (PPP) solutions in terms of accuracy was investigated. For this purpose, a field test was carried out in Çorum province, Turkey, on 11 September 2019. Within this context, a Geodetic Point (GP) was established and precisely coordinated. A static GNSS measurement was occupied on the GP for about 4-hour time at 0.10 second (s)/10 Hz measurement intervals with the Trimble R10 geodetic grade GNSS receiver. The original observation file was converted to RINEX format and then decimated into the different data sampling rates as 0.2 s, 0.5 s, 1 s, 5 s, 10 s, 30 s, 60 s, and 120 s. All these RINEX observation files were submitted to the Canadian Spatial Reference System-Precise Point Positioning (CSRS-PPP) online processing service the day after the data collection date by choosing both static and kinematic processing options. In this way, PPP-derived static coordinates, and the kinematic coordinates of each measurement epoch were calculated. The PPP-derived coordinates obtained from each decimated sampling intervals were compared to known coordinates of the GP for northing, easting, 2D position, and height components. According to the static and kinematic processing results, high data sampling rates did not change the PPP solutions in terms of accuracy when compared to the results obtained using lower sampling rates. The results of this study imply that it was not necessary to collect GNSS data with high-rate intervals for many surveying projects requiring cm-level accuracy.
Numéro de notice :	A2021-558
Affiliation des auteurs :	non IGN
Thématique :	POSITIONNEMENT
Nature :	Article
nature-HAL :	ArtAvecCL-RevueIntern
DOI :	10.1080/10095020.2020.1842811
Date de publication en ligne :	25/11/2020
En ligne :	https://doi.org/10.1080/10095020.2020.1842811
Format de la ressource électronique :	URL article
Permalink :	https://documentation.ensg.eu/index.php?lvl=notice_display&id=98111

Ionospheric irregularity layer height and thickness estimation with a GNSS receiver array

Ionospheric irregularity layer height and thickness estimation with a GNSS receiver array [Article/Communication] / Seebany Datta-Barua, Auteur ; Yang Su, Auteur ; Aurora López Rubio, Auteur ; et al., Auteur . - 2021 . - pp 6198 - 6207.bibliographieLangues : Anglais (eng)in IEEE Transactions on geoscience and remote sensing > Vol 59 n° 7 (July 2021) . - pp 6198 - 6207

Descripteur :	[Vedettes matières IGN] Géodésie spatiale[Termes IGN] Alaska (Etats-Unis)[Termes IGN] hauteur de la couche ionosphérique[Termes IGN] méthode de Monte-Carlo[Termes IGN] modèle ionosphérique[Termes IGN] phase GNSS[Termes IGN] rapport signal sur bruit[Termes IGN] scintillation[Termes IGN] série temporelle[Termes IGN] signal GNSS
Résumé :	(auteur) This work develops a method by which a kilometer-spaced array of Global Navigation Satellite System (GNSS) scintillation receivers can be used to estimate the ionospheric irregularity layer height and thickness and associated uncertainties on those estimates. Spectra of filtered signal power and phase data are used to estimate these quantities by comparing the observed ratio of the log of the power spectrum to the phase spectrum with the Rytov weak scatter theoretical ratio. A Monte Carlo simulation of noise on the input signal and the irregularity drift velocity is used to quantify the error in estimates of height and thickness. The method is tested using data from the Scintillation Auroral Global Positioning System (GPS) Array (SAGA) sited in the auroral zone at Poker Flat Research Range, Alaska. For the 30-min scintillation period studied, the technique identifies ionospheric scattering from a thick F layer, which correlates well with on-site incoherent scatter radar measurements of peak electron density, for an event previously identified in the literature as likely due to F layer.
Numéro de notice :	A2021-539
Affiliation des auteurs :	non IGN
Thématique :	POSITIONNEMENT
Nature :	Article
DOI :	10.1109/TGRS.2020.3024173
Date de publication en ligne :	12/10/2020
En ligne :	https://doi.org/10.1109/TGRS.2020.3024173
Format de la ressource électronique :	URL article
Permalink :	https://documentation.ensg.eu/index.php?lvl=notice_display&id=98013

Comparison of polar ionospheric behavior at Arctic and Antarctic regions for improved satellite-based positioning

Comparison of polar ionospheric behavior at Arctic and Antarctic regions for improved satellite-based positioning [Article/Communication] / Arun Kumar Singh, Auteur . - 2021 . - pp 269 - 277.BibliographieLangues : Anglais (eng)in Journal of applied geodesy > vol 15 n° 3 (July 2021) . - pp 269 - 277

Descripteur :

[Vedettes matières IGN] Géodésie spatiale[Termes IGN] amplitude[Termes IGN] Antarctique[Termes IGN] Arctique[Termes IGN] champ géomagnétique[Termes IGN] ionosphère[Termes IGN] magnétosphère[Termes IGN] phase[Termes IGN] pôle[Termes IGN] positionnement par GNSS[Termes IGN] retard ionosphèrique[Termes IGN] scintillation[Termes IGN] teneur totale en électrons[Termes IGN] variation temporelle

Résumé :

(Auteur) In this paper, we investigate the hemispheric symmetric and asymmetric characteristics of ionospheric total electron content (TEC) and its dependency on the interplanetary magnetic field (IMF) in the northern and southern polar ionosphere. The changes in amplitude and phase scintillation are also probed through Global Ionospheric Scintillation and TEC monitoring (GISTM) systems recordings at North pole [Himadri station; Geographic 78°55′ N, 11°56′ E] and South pole [Maitri station; Geographic 70°46′ S 11°44′ E]. Observations show the range of %TEC variability being relatively more over Antarctic region (−40 % to 60 %) than Arctic region (−25 % to 25 %), corroborating the role of the dominant solar photoionization production process. Our analysis confirms that TEC variation at polar latitudes is a function of magnetosphere-ionosphere coupling, depending on interplanetary magnetic field (IMF) orientation and magnitude in the X ( Bx), Y ( By), and Z ( Bz) plane. Visible enhancement in TEC is noticed in the northern polar latitude when Bx0 whereas the southern polar latitude perceives TEC enhancements with Bx>0, −6nT

Ordered subsets-constrained ART algorithm for ionospheric tomography by combining VTEC data

Ordered subsets-constrained ART algorithm for ionospheric tomography by combining VTEC data [Article/Communication] / Dunyong Zheng, Auteur ; Yibin Yao, Auteur ; Wenfeng Nie, Auteur ; et al., Auteur . - 2021 . - pp 7051 - 7061.bibliographieLangues : Anglais (eng)in IEEE Transactions on geoscience and remote sensing > vol 59 n° 8 (August 2021) . - pp 7051 - 7061

Descripteur :	[Vedettes matières IGN] Applications de géodésie spatiale[Termes IGN] données GNSS[Termes IGN] modèle ionosphérique[Termes IGN] teneur totale en électrons[Termes IGN] teneur verticale totale en électrons[Termes IGN] tomographie par GPS
Résumé :	(auteur) Computerized ionospheric tomography is an important technique for ionosphere investigation. However, it is an ill-posed problem owing to an insufficient amount of available data, because of which the distributions of ionospheric electron density (IED) cannot be reconstructed accurately. In light of this, the ordered subsets-constrained algebraic reconstruction technique (OS_CART) is developed here using vertical total electron content (VTEC) data to solve this problem, where the VTEC derived from the slant total electron content (STEC) of Global Navigation Satellite System (GNSS) signal paths is used to compensate for the lack of data provided by GNSS observations in inversion regions, and the OS_CART is also used to improve the spatial resolution and inversion efficiency. The proposed method was validated by conducting numerical experiments using GNSS and independent ionosonde data in both quiescent and disturbed ionospheric conditions. In contrast to classical methods of ionospheric tomography, the proposed method exhibited significantly higher reconstruction accuracy. While delivering a comparable accuracy to that of traditional methods in terms of self-consistency validation using STEC data and without overfitting, the proposed method yielded a more than 90% improvement over the self-consistency validation using VTEC data. In addition, a better daily description of the ionosphere was obtained using the proposed method, where an increase in the peak height and irregular changes to the IED, associated with variations in the number of epochs and the occurrence of magnetic storms, were observed. Overall, the results reveal that the proposed method is a useful tool for research on space weather.
Numéro de notice :	A2021-634
Affiliation des auteurs :	non IGN
Thématique :	POSITIONNEMENT
Nature :	Article
nature-HAL :	ArtAvecCL-RevueIntern
DOI :	10.1109/TGRS.2020.3029819
Date de publication en ligne :	28/10/2020
En ligne :	https://doi.org/10.1109/TGRS.2020.3029819
Format de la ressource électronique :	URL article
Permalink :	https://documentation.ensg.eu/index.php?lvl=notice_display&id=98297

Estimation of code observation-specific biases (OSBs) for the modernized multi-frequency and multi-GNSS signals: an undifferenced and uncombined approach

Estimation of code observation-specific biases (OSBs) for the modernized multi-frequency and multi-GNSS signals: an undifferenced and uncombined approach [Article/Communication] / Teng Liu, Auteur ; Baocheng Zhang, Auteur . - 2021 . - n° 97.bibliographieLangues : Anglais (eng)in Journal of geodesy > vol 95 n° 8 (August 2021) . - n° 97

Descripteur :	[Termes IGN] code GNSS[Termes IGN] combinaison linéaire[Termes IGN] erreur systématique de code différentiel[Termes IGN] fréquence multiple[Termes IGN] phase GNSS[Termes IGN] retard ionosphèrique[Termes IGN] signal GNSS[Termes IGN] teneur verticale totale en électrons[Vedettes matières IGN] Traitement de données GNSS
Résumé :	(auteur) For a long time, code biases of global navigation satellite system (GNSSs) have been parameterized and presented in the differential mode, namely the commonly-known differential code biases (DCB). However, with the continuous modernization of the existing constellations and rapid developments of the new systems, various new frequencies and types of GNSS signals are emerging, which makes the traditional DCB mode less flexible and efficient to handle the new situations and challenges. Recently, code biases in observation-specific representation, which finally provides observation-specific biases (OSBs), turns out to be a good solution and is gradually accepted by the GNSS community, though existing products are generated based on routine procedures and few studies concentrate on the new methods. In view of it, this study aims to propose a rigorous, flexible and efficient approach of OSB estimation for the modernized multi-frequency and, multi-GNSS signals. To achieve this, instead of being-based on linear combinations of raw observations in the existing literature, an extended multi-frequency geometry-free model is first established based on undifferenced and uncombined observations, which can adapt to observations of arbitrary frequencies and types in a compatible and flexible way and is used to extract the various types of linear combinations of the interested OSBs. Then, regarding the previously-obtained linear combinations as virtual observables after station-based ionosphere modeling, all OSB parameters are setup and estimated in a single normal equation, during which a clear identification and elimination of the rank deficiencies in the linear system is carefully conducted by introducing different types of constraints. The proposed new method is validated with one month of real data to generate totally 32 types of OSBs for GPS, GLONASS, Galileo, BeiDou, and QZSS. The estimated OSBs are compared with existing OSB and DCB products from other agencies. Results indicate that the proposed method can be used as a flexible and precise method for full-constellation and full-type OSB estimation.
Numéro de notice :	A2021-584
Affiliation des auteurs :	non IGN
Thématique :	POSITIONNEMENT
Nature :	Article
nature-HAL :	ArtAvecCL-RevueIntern
DOI :	10.1007/s00190-021-01549-x
Date de publication en ligne :	12/08/2021
En ligne :	https://doi.org/10.1007/s00190-021-01549-x
Format de la ressource électronique :	URL article
Permalink :	https://documentation.ensg.eu/index.php?lvl=notice_display&id=98199

Integer-estimable FDMA model as an enabler of GLONASS PPP-RTK

Integer-estimable FDMA model as an enabler of GLONASS PPP-RTK [Article/Communication] / Baocheng Zhang, Auteur ; Pengyu Hou, Auteur ; Jiuping Zha, Auteur ; Teng Liu, Auteur . - 2021 . - n° 91.bibliographieLangues : Anglais (eng)in Journal of geodesy > vol 95 n° 8 (August 2021) . - n° 91

Descripteur :	[Vedettes matières IGN] Applications de géodésie spatiale[Termes IGN] ambiguïté entière[Termes IGN] CDMA[Termes IGN] correction ionosphérique[Termes IGN] décalage d'horloge[Termes IGN] positionnement cinématique en temps réel[Termes IGN] positionnement par GLONASS[Termes IGN] positionnement par GPS[Termes IGN] positionnement ponctuel précis[Termes IGN] résolution d'ambiguïté[Termes IGN] temps de convergence
Résumé :	(auteur) PPP-RTK extends the precise point positioning (PPP) concept by incorporating the idea of integer ambiguity resolution underlying the real-time kinematic (RTK) technique, making rapid initialization and high accuracy attainable with a standalone receiver. While PPP-RTK has been well achieved by using global navigation satellite system code division multiple access observables, GLONASS PPP-RTK is nonetheless challenging due to the nature of frequency division multiple access (FDMA) observables. In this work, we present a GLONASS PPP-RTK concept that takes advantage of the integer-estimable FDMA (IE-FDMA) model recently proposed in Teunissen (in GPS Solut 23(4):1–19, 2019. https://doi.org/10.1007/s10291-019-0889-0) to guarantee rigorous integer ambiguity resolution and simultaneously takes care of the presence of the inter-frequency biases (IFBs) in homogeneous and heterogeneous network configurations. When conducting GLONASS PPP-RTK based on a network of homogeneous receivers, code and phase observation equations are used to construct the IE-FDMA model, in which the IFBs are implicitly eliminated through reparameterization. For a network consisting of heterogeneous receivers, we exclude the code observables and develop a phase-only IE-FDMA model instead, thereby circumventing the adverse effects of IFBs. For verification purposes, we collect a set of five-day global positioning system (GPS) and GLONASS data from two regional networks: one equipped with homogeneous receivers and another with heterogeneous receivers. The results show that the GLONASS-specific network corrections, including satellite clocks, satellite phase biases, and ionospheric delays estimated by the two networks, are as precise as those of their GPS-specific counterparts. Via satellite clock and phase bias corrections, we succeed in fixing both GPS and GLONASS ambiguities, shortening the convergence time to 5 (12) min, compared to 11 (18) min of ambiguity-float positioning in the case of a homogeneous (heterogeneous) network with a data sampling rate of 30 s. For ambiguity-fixed positioning, the convergence time defined in this work also indicates the time to first fix since the positioning error converges to the centimeter level once successful integer ambiguity resolution is achieved. Adding ionospheric corrections further speeds up the initialization in the two networks, with the convergence time being reduced to 0.5 (3) min. Compared with GPS-only positioning, the integration of GPS and GLONASS yields an improvement of 8–34% in accuracy and leads to a reduction of 25–50% in convergence.
Numéro de notice :	A2021-585
Affiliation des auteurs :	non IGN
Thématique :	POSITIONNEMENT
Nature :	Article
nature-HAL :	ArtAvecCL-RevueIntern
DOI :	10.1007/s00190-021-01546-0
Date de publication en ligne :	26/07/2021
En ligne :	https://doi.org/10.1007/s00190-021-01546-0
Format de la ressource électronique :	URL article
Permalink :	https://documentation.ensg.eu/index.php?lvl=notice_display&id=98200

Tropospheric and range biases in Satellite Laser Ranging

Tropospheric and range biases in Satellite Laser Ranging [Article/Communication] / Mateusz Drożdżewski, Auteur ; Krzysztof Sosnica, Auteur . - 2021 . - n° 100.bibliographieLangues : Anglais (eng)in Journal of geodesy > vol 95 n° 9 (September 2021) . - n° 100

Descripteur :	[Vedettes matières IGN] Géodésie spatiale[Termes IGN] champ de pesanteur terrestre[Termes IGN] correction troposphérique[Termes IGN] données Lageos[Termes IGN] données TLS (télémétrie)[Termes IGN] erreur systématique[Termes IGN] géocentre[Termes IGN] harmonique sphérique[Termes IGN] retard troposphérique zénithal[Termes IGN] télémétrie laser sur satellite
Résumé :	(auteur) The Satellite Laser Ranging (SLR) technique provides very accurate distance measurements to artificial Earth satellites. SLR is employed for the realization of the origin and the scale of the terrestrial reference frame. Despite the high precision, SLR observations can be affected by various systematic errors. So far, range biases were used to account for systematic measurement errors and mismodeling effects in SLR. Range biases are constant for all elevation angles and independent of the measured distance to a satellite. Recently, intensity-dependent biases for single-photon SLR detectors and offsets of barometer readings and meteorological devices were reported for some SLR stations. In this paper, we study the possibility of the direct estimation of tropospheric biases from SLR observations to LAGEOS satellites. We discuss the correlations between the station heights, range biases, tropospheric biases, and their impact on the repeatability of station coordinates, geocenter motion, and the global scale of the reference frame. We found that the solution with the estimation of tropospheric biases provides more stable station coordinates than the solution with the estimation of range biases. From the common estimation of range and tropospheric biases, we found that most of the systematic effects at SLR stations are better absorbed by elevation-dependent tropospheric biases than range biases which overestimate the total bias effect. The estimation of tropospheric biases changes the SLR-derived global scale by 0.3 mm and the geocenter coordinates by 1 mm for the Z component, causing thus an offset in the realization of the reference frame origin. Estimation of range biases introduces an offset in some SLR-derived low-degree spherical harmonics of the Earth’s gravity field. Therefore, considering elevation-dependent tropospheric and intensity biases is essential for deriving high-accuracy geodetic parameters.
Numéro de notice :	A2021-621
Affiliation des auteurs :	non IGN
Thématique :	POSITIONNEMENT
Nature :	Article
nature-HAL :	ArtAvecCL-RevueIntern
DOI :	10.1007/s00190-021-01554-0
Date de publication en ligne :	21/08/2021
En ligne :	https://doi.org/10.1007/s00190-021-01554-0
Format de la ressource électronique :	URL article
Permalink :	https://documentation.ensg.eu/index.php?lvl=notice_display&id=98237

A new approach for the development of grid models calculating tropospheric key parameters over China

A new approach for the development of grid models calculating tropospheric key parameters over China [Article/Communication] / Ge Zhu, Auteur ; Liangke Huang, Auteur ; Lilong Liu, Auteur ; et al., Auteur . - 2021 . - n° 3546.bibliographieLangues : Anglais (eng)in Remote sensing > vol 13 n° 17 (September-1 2021) . - n° 3546

Descripteur :	[Vedettes matières IGN] Géodésie spatiale[Termes IGN] Chine[Termes IGN] données maillées[Termes IGN] données météorologiques[Termes IGN] MERRA[Termes IGN] positionnement par GNSS[Termes IGN] propagation troposphérique[Termes IGN] retard troposphérique[Termes IGN] série temporelle[Termes IGN] teneur en vapeur d'eau
Résumé :	(auteur) Pressure, water vapor pressure, temperature, and weighted mean temperature (Tm) are tropospheric parameters that play an important role in high-precision global navigation satellite system navigation (GNSS). As accurate tropospheric parameters are obligatory in GNSS navigation and GNSS water vapor detection, high-precision modeling of tropospheric parameters has gained widespread attention in recent years. A new approach is introduced to develop an empirical tropospheric delay model named the China Tropospheric (CTrop) model, providing meteorological parameters based on the sliding window algorithm. The radiosonde data in 2017 are treated as reference values to validate the performance of the CTrop model, which is compared to the canonical Global Pressure and Temperature 3 (GPT3) model. The accuracy of the CTrop model in regards to pressure, water vapor pressure, temperature, and weighted mean temperature are 5.51 hPa, 2.60 hPa, 3.09 K, and 3.35 K, respectively, achieving an improvement of 6%, 9%, 10%, and 13%, respectively, when compared to the GPT3 model. Moreover, three different resolutions of the CTrop model based on the sliding window algorithm are also developed to reduce the amount of gridded data provided to the users, as well as to speed up the troposphere delay computation process, for which users can access model parameters of different resolutions for their requirements. With better accuracy of estimating the tropospheric parameters than that of the GPT3 model, the CTrop model is recommended to improve the performance of GNSS positioning and navigation.
Numéro de notice :	A2021-688
Affiliation des auteurs :	non IGN
Thématique :	POSITIONNEMENT
Nature :	Article
DOI :	10.3390/rs13173546
Date de publication en ligne :	06/09/2021
En ligne :	https://doi.org/10.3390/rs13173546
Format de la ressource électronique :	URL article
Permalink :	https://documentation.ensg.eu/index.php?lvl=notice_display&id=98423

Influence of aperiodic non-tidal atmospheric and oceanic loading deformations on the stochastic properties of global GNSS vertical land motion time series

Influence of aperiodic non-tidal atmospheric and oceanic loading deformations on the stochastic properties of global GNSS vertical land motion time series [Article/Communication] / Kevin Gobron, Auteur ; Paul Rebischung, Auteur ; Michel Van Camp, Auteur ; Alain Demoulin, Auteur ; Olivier de Viron, Auteur . - 2021 . - n° e2021JB022370.bibliographie This study has been financially supported by the Direction Générale de l’Armement (DGA), the Nouvelle-Aquitaine region, and the Centre National des Etudes Spatiales (CNES) as an application of the geodesy missions. This research was also supported by the Brain LASUGEO project entitled ”monitoring LAnd SUbsidence caused by Groundwater exploitation through gEOdetic measurements” funded by the Belgian Sciences Policy. This is IPGP contribution number 4214. Langues : Anglais (eng)in Journal of geophysical research : Solid Earth > vol 126 n° 9 (September 2021) . - n° e2021JB022370

Descripteur :	[Vedettes matières IGN] Géodésie spatiale[Termes IGN] coordonnées GNSS[Termes IGN] déformation verticale de la croute terrestre[Termes IGN] erreur systématique[Termes IGN] résidu[Termes IGN] série temporelle[Termes IGN] station permanente[Termes IGN] surcharge atmosphérique[Termes IGN] surcharge océanique
Résumé :	(auteur) Monitoring vertical land motions (VLMs) at the level of 0.1 mm/yr remains one of the most challenging scientific applications of global navigation satellite systems (GNSS). Such small rates of change can result from climatic and tectonic phenomena, and their detection is important to many solid Earth-related studies, including the prediction of coastal sea-level change and the understanding of intraplate deformation. Reaching a level of precision allowing to detect such small signals requires a thorough understanding of the stochastic variability in GNSS VLM time series. This paper investigates how the aperiodic part of non-tidal atmospheric and oceanic loading (NTAOL) deformations influences the stochastic properties of VLM time series. Using the time series of over 10,000 stations, we describe the impact of correcting for NTAOL deformation on 5 complementary metrics, namely: the repeatability of position residuals, the power-spectrum of position residuals, the estimated time-correlation properties, the corresponding velocity uncertainties, and the spatial correlation of the residuals. We show that NTAOL deformations cause a latitude-dependent bias in white noise plus power-law model parameter estimates. This bias is significantly mitigated when correcting for NTAOL deformation, which reduces velocity uncertainties at high latitudes by 70%. Therefore, removing NTAOL deformation before the statistical analysis of VLM time series might help to detect subtle VLM signals in these areas. Our spatial correlation analysis also reveals a seasonality in the spatial correlation of the residuals, which is reduced after removing NTAOL deformation, confirming that NTAOL is a clear source of common-mode errors in GNSS VLM time series.
Numéro de notice :	A2021-783
Affiliation des auteurs :	UMR IPGP-Géod+Ext (2020- )
Autre URL associée :	vers HAL
Thématique :	POSITIONNEMENT
Nature :	Article
nature-HAL :	ArtAvecCL-RevueIntern
DOI :	10.1029/2021JB022370
Date de publication en ligne :	01/09/2021
En ligne :	https://doi.org/10.1029/2021JB022370
Format de la ressource électronique :	URL article
Permalink :	https://documentation.ensg.eu/index.php?lvl=notice_display&id=98954

Sensitivity of change-point detection and trend estimates to GNSS IWV time series properties

Sensitivity of change-point detection and trend estimates to GNSS IWV time series properties [Article/Communication] / Khanh Ninh Nguyen, Auteur ; Annarosa Quarello, Auteur ; Olivier Bock, Auteur ; Emilie Lebarbier, Auteur . - 2021 . - n° 1102.bibliographieLangues : Anglais (eng)in Atmosphere > vol 12 n° 9 (September 2021) . - n° 1102

Descripteur :	[Vedettes matières IGN] Applications de géodésie spatiale[Termes IGN] analyse de sensibilité[Termes IGN] coordonnées GNSS[Termes IGN] données météorologiques[Termes IGN] incertitude géométrique[Termes IGN] segmentation[Termes IGN] série temporelle[Termes IGN] teneur intégrée en vapeur d'eau
Résumé :	(auteur) This study investigates the sensitivity of the GNSSseg segmentation method to change in: GNSS data processing method, length of time series (17 to 25 years), auxiliary data used in the integrated water vapor (IWV) conversion, and reference time series used in the segmentation (ERA-Interim versus ERA5). Two GNSS data sets (IGS repro1 and CODE REPRO2015), representative of the first and second IGS reprocessing, were compared. Significant differences were found in the number and positions of detected change-points due to different a priori ZHD models, antenna/radome calibrations, and mapping functions. The more recent models used in the CODE solution have reduced noise and allow the segmentation to detect smaller offsets. Similarly, the more recent reanalysis ERA5 has reduced representativeness errors, improved quality compared to ERA-Interim, and achieves higher sensitivity of the segmentation. Only 45–50% of the detected change-points are similar between the two GNSS data sets or between the two reanalyses, compared to 70–80% when the length of the time series or the auxiliary data are changed. About 35% of the change-points are validated with respect to metadata. The uncertainty in the homogenized trends is estimated to be around 0.01–0.02 kg m−2 year−1.
Numéro de notice :	A2021-791
Affiliation des auteurs :	UMR IPGP-Géod+Ext (2020- )
Thématique :	POSITIONNEMENT
Nature :	Article
nature-HAL :	ArtAvecCL-RevueIntern
DOI :	10.3390/atmos12091102
En ligne :	https://doi.org/10.3390/atmos12091102
Format de la ressource électronique :	URL article
Permalink :	https://documentation.ensg.eu/index.php?lvl=notice_display&id=98993

Predicting total electron content in ionosphere using vector autoregression model during geomagnetic storm

Predicting total electron content in ionosphere using vector autoregression model during geomagnetic storm [Article/Communication] / Sumitra Iyer, Auteur ; Alka Mahajan, Auteur . - 2021 . - pp 279 - 291.bibliographieLangues : Anglais (eng)in Journal of applied geodesy > vol 15 n° 4 (October 2021) . - pp 279 - 291

Descripteur :	[Vedettes matières IGN] Géodésie spatiale[Termes IGN] autorégression[Termes IGN] déformation temporelle dynamique[Termes IGN] format RINEX[Termes IGN] Inde[Termes IGN] modèle de simulation[Termes IGN] modèle ionosphérique[Termes IGN] série temporelle[Termes IGN] signal GPS[Termes IGN] tempête magnétique[Termes IGN] teneur totale en électrons[Termes IGN] teneur verticale totale en électrons
Résumé :	(auteur) The ionospheric total electron content (TEC) severely impacts the positional accuracy of a single frequency Global Positioning System (GPS) receiver at the equatorial latitudes. The ionosphere causes a frequency-dependent group delay in the GPS-ranging signals, which reduces the receiver’s accuracy. Further, the variations in TEC due to various space weather phenomena make the ionosphere’s behaviour nonhomogeneous and complex. Hence, developing an accurate forecast model that can track the dynamic behaviour of the ionosphere remains a challenge. However, advances in emerging data-driven algorithms have been found helpful in tracking non-stationary behavior in TEC. These models help forecast the delays in advance. The multivariate Vector Autoregression model (VAR) predicts the Ionospheric TEC in the proposed model. The prediction model uses input data compiled in real-time from the lag values of incoming TEC data and features extracted from TEC. The TEC is predicted in real-time and tested for different prediction intervals. The metrics – Mean Percentage Error (MAPE), Mean Absolute Error (MAE), and Root Mean Square Error (RMSE) are used for testing and validating the accuracy of the model statistically. Testing the predicted output accuracy is also done with the dynamic time warping (DTW) algorithm by comparing it with the actual value obtained from the dual-frequency receiver. The model is tested for storm days of the year 2015 for Bangalore and Hyderabad stations and found to be reliable and accurate. A prediction interval of twenty-minute shows the highest accuracy with an error within 10 TECU for all the storm days.
Numéro de notice :	A2021-745
Affiliation des auteurs :	non IGN
Thématique :	POSITIONNEMENT
Nature :	Article
DOI :	10.1515/jag-2021-0015
Date de publication en ligne :	23/06/2021
En ligne :	https://doi.org/10.1515/jag-2021-0015
Format de la ressource électronique :	URL article
Permalink :	https://documentation.ensg.eu/index.php?lvl=notice_display&id=98717

Ionospheric tomographic common clock model of undifferenced uncombined GNSS measurements

Ionospheric tomographic common clock model of undifferenced uncombined GNSS measurements [Article/Communication] / German Olivares-Pulido, Auteur ; Manuel Hernández-Pajares, Auteur ; Haixia Lyu, Auteur ; et al., Auteur . - 2021 . - n° 122.bibliographieLangues : Anglais (eng)in Journal of geodesy > vol 95 n° 11 (November 2021) . - n° 122

Descripteur :	[Termes IGN] correction ionosphérique[Termes IGN] horloge du satellite[Termes IGN] mesurage par GNSS[Termes IGN] modèle ionosphérique[Termes IGN] phase[Termes IGN] positionnement ponctuel précis[Termes IGN] teneur totale en électrons[Termes IGN] tomographie par GPS[Termes IGN] voxel[Termes IGN] Wide Area Augmentation System[Vedettes matières IGN] Traitement de données GNSS
Résumé :	(auteur) In this manuscript, we introduce the Ionospheric Tomographic Common Clock (ITCC) model of undifferenced uncombined GNSS measurements. It is intended for improving the Wide Area precise positioning in a consistent and simple way in the multi-GNSS context, and without the need of external precise real-time products. This is the case, in particular, of the satellite clocks, which are estimated at the Wide Area GNSS network Central Processing Facility (CPF) referred to the reference receiver one; and the precise realtime ionospheric corrections, simultaneously computed under a voxel-based tomographic model with satellite clocks and other geodetic unknowns, from the uncombined and undifferenced pseudoranges and carrier phase measurements at the CPF from the Wide Area GNSS network area. The model, without fixing the carrier phase ambiguities for the time being (just constraining them by the simultaneous solution of both ionospheric and geometric components of the uncombined GNSS model), has been successfully applied and assessed against previous precise positioning techniques. This has been done by emulating real-time conditions for Wide Area GPS users during 2018 in Poland.
Numéro de notice :	A2021-776
Affiliation des auteurs :	non IGN
Thématique :	POSITIONNEMENT
Nature :	Article
nature-HAL :	ArtAvecCL-RevueIntern
DOI :	10.1007/s00190-021-01568-8
Date de publication en ligne :	13/10/2021
En ligne :	https://doi.org/10.1007/s00190-021-01568-8
Format de la ressource électronique :	URL article
Permalink :	https://documentation.ensg.eu/index.php?lvl=notice_display&id=98839

A mean-squared-error condition for weighting ionospheric delays in GNSS baselines

A mean-squared-error condition for weighting ionospheric delays in GNSS baselines [Article/Communication] / Peter J.G. Teunissen, Auteur ; Amir Khodabandeh, Auteur . - 2021 . - n° 118.bibliographieLangues : Anglais (eng)in Journal of geodesy > vol 95 n° 11 (November 2021) . - n° 118

Descripteur :	[Termes IGN] erreur moyenne quadratique[Termes IGN] ligne de base[Termes IGN] pondération[Termes IGN] propagation ionosphérique[Termes IGN] retard ionosphèrique[Vedettes matières IGN] Traitement de données GNSS
Résumé :	(auteur) Although ionosphere-weighted GNSS parameter estimation is a popular technique for strengthening estimator performance in the presence of ionospheric delays, no provable rules yet exist that specify the needed weighting in dependence on ionospheric circumstances. The goal of the present contribution is therefore to develop and present the ionospheric conditions that need to be satisfied in order for the ionosphere-weighted solution to be mean squared error (MSE) superior to the ionosphere-float solution. When satisfied, the presented conditions guarantee from an MSE performance view, when (a) the ionosphere-fixed solution can be used, (b) the ionosphere-float solution must be used, or (c) an ionosphere-weighted solution can be used.
Numéro de notice :	A2021-777
Affiliation des auteurs :	non IGN
Thématique :	POSITIONNEMENT
Nature :	Article
nature-HAL :	ArtAvecCL-RevueIntern
DOI :	10.1007/s00190-021-01569-7
Date de publication en ligne :	10/10/2021
En ligne :	https://doi.org/10.1007/s00190-021-01569-7
Format de la ressource électronique :	URL article
Permalink :	https://documentation.ensg.eu/index.php?lvl=notice_display&id=98840

Spatiotemporal analysis of precipitable water vapor using ANFIS and comparison against voxel-based tomography and radiosonde

Spatiotemporal analysis of precipitable water vapor using ANFIS and comparison against voxel-based tomography and radiosonde [Article/Communication] / Mir Reza Ghaffari Razin, Auteur ; Samed Inyurt, Auteur . - 2021 . - n° 1.bibliographieLangues : Anglais (eng)in GPS solutions > vol 26 n° 1 (January 2022) . - n° 1

Descripteur :	[Vedettes matières IGN] Applications de géodésie spatiale[Termes IGN] Inférence floue[Termes IGN] modélisation spatio-temporelle[Termes IGN] positionnement ponctuel précis[Termes IGN] précipitation[Termes IGN] radiosondage[Termes IGN] retard troposphérique zénithal[Termes IGN] station GPS[Termes IGN] vapeur d'eau[Termes IGN] voxel
Résumé :	(auteur) Water vapor (WV) is one of the most important parameters in meteorological studies. Using an adaptive neuro-fuzzy inference system (ANFIS), a new method has been proposed for spatiotemporal modeling of precipitable WV (PWV). In a first step, the tropospheric zenith wet delay (ZWD) is calculated using the observations of 23 GPS stations in the northwest of Iran. Out of these 23 stations, 21 stations for training and 2 stations for testing and validating were selected. The observations are for 15 days, ranging from day of year (DOY) 300 to 314 in 2011. The reason for choosing this area and time interval is the availability of a complete set of data. Then, the values of ZWD are converted to PWV. The PWV values obtained from this step are considered as the output of the ANFIS. Also, the latitude and longitude values of the GPS stations, the DOY, observational time (min), temperature (T), pressure (P), and relative humidity (RH) are considered input to ANFIS. The ANFIS network is trained using the back-propagation algorithm. After the training step, the PWV values are evaluated at 2 test stations, KLBR and GGSH, and at Tabriz radiosonde station (38.08° N, 46.28°E). For a more accurate evaluation, all the results of the new method are compared with the voxel-based tomography model. The evaluation of the results is performed using the relative error, standard deviation, correlation coefficient, and root-mean-square error (RMSE). Also, precise point positioning (PPP) is used to better evaluate the proposed model at test stations. The value of the correlation coefficient at the radiosonde station for the ANFIS and voxel is 0.90 and 0.87, respectively. Also, the minimum RMSE calculated for the ANFIS and voxel are 1.02 and 1.06 mm, respectively. In the PPP analysis, an improvement of about 4 mm is observed in the coordinates of the test stations using ANFIS. The results confirm the capability and high accuracy of the proposed model in determining the temporal and spatial variations of PWV.
Numéro de notice :	A2022-003
Affiliation des auteurs :	non IGN
Thématique :	POSITIONNEMENT
Nature :	Article
nature-HAL :	ArtAvecCL-RevueIntern
DOI :	10.1007/s10291-021-01184-1
Date de publication en ligne :	19/10/2021
En ligne :	https://doi.org/10.1007/s10291-021-01184-1
Format de la ressource électronique :	URL article
Permalink :	https://documentation.ensg.eu/index.php?lvl=notice_display&id=98828

Conventional and neural network-based water vapor density model for GNSS troposphere tomography

Conventional and neural network-based water vapor density model for GNSS troposphere tomography [Article/Communication] / Chen Liu, Auteur ; Yibin Yao, Auteur ; Chaoqian Xu, Auteur . - 2021 . - n° 4.bibliographieLangues : Anglais (eng)in GPS solutions > vol 26 n° 1 (January 2022) . - n° 4

Descripteur :	[Vedettes matières IGN] Applications de géodésie spatiale[Termes IGN] classification par réseau neuronal[Termes IGN] erreur absolue[Termes IGN] étalonnage de modèle[Termes IGN] modèle météorologique[Termes IGN] propagation troposphérique[Termes IGN] tomographie par GPS[Termes IGN] vapeur d'eau[Termes IGN] voxel
Résumé :	(auteur) Global navigation satellite system (GNSS) water vapor (WV) tomography is a promising technique to reconstruct the three-dimensional (3D) WV field. However, this technique usually suffers from the ill-posed problem caused by the poor geometry of GNSS rays, resulting in underdetermined tomographic equations. Such equations often rely on iterative methods for solving, but conventional iterative approaches require accurate initial WV density. To address this demand, we proposed two models for WV density estimation. One is the conventional model (CO model) that consists of an exponential model and a linear least-squares model, which are used to describe the spatial and temporal variability of the WV density, respectively. The other is a neural network model (NN model) that uses a backpropagation neural network (BPNN) to fit the nonlinear variation of WV density in both spatial and temporal domains. WV density derived from a Hong Kong (HK) radiosonde station (RS) during 2020 was used to validate the proposed models. Validation results show that both models well describe the spatial and temporal distribution of the WV density. The NN model exhibits better prediction performance than the CO model in terms of root mean square error (RMSE) and bias. We also applied the proposed models to GNSS WV tomography to test their performance in extreme weather conditions. Test results show that the proposed model-based GNSS tomography can correct the content of WV density but cannot accurately sense its irregular distribution.
Numéro de notice :	A2022-005
Affiliation des auteurs :	non IGN
Thématique :	POSITIONNEMENT
Nature :	Article
nature-HAL :	ArtAvecCL-RevueIntern
DOI :	10.1007/s10291-021-01188-x
Date de publication en ligne :	23/10/2021
En ligne :	https://doi.org/10.1007/s10291-021-01188-x
Format de la ressource électronique :	URL article
Permalink :	https://documentation.ensg.eu/index.php?lvl=notice_display&id=98920

Baseline-dependent clock offsets in VLBI data analysis

Baseline-dependent clock offsets in VLBI data analysis [Article/Communication] / Hana Krásná, Auteur ; Frédéric Jaron, Auteur ; Jacob Gruber, Auteur ; et al., Auteur . - 2021 . - n° 126.bibliographieLangues : Anglais (eng)in Journal of geodesy > vol 95 n° 12 (December 2021) . - n° 126

Descripteur :	[Vedettes matières IGN] Systèmes de référence et réseaux[Termes IGN] bande S[Termes IGN] décalage d'horloge[Termes IGN] données ITGB[Termes IGN] horloge atomique[Termes IGN] interférométrie à très grande base[Termes IGN] ligne de base[Termes IGN] paramètres d'orientation de la Terre[Termes IGN] retard ionosphèrique
Résumé :	(auteur) The primary goal of the geodetic Very Long Baseline Interferometry (VLBI) technique is to provide highly accurate terrestrial and celestial reference frames as well as Earth orientation parameters. In compliance with the concept of VLBI, additional parameters reflecting relative offsets and variations of the atomic clocks of the radio telescopes have to be estimated. In addition, reality shows that in many cases significant offsets appear in the observed group delays for individual baselines which have to be compensated for by estimating so-called baseline-dependent clock offsets (BCOs). For the first time, we systematically investigate the impact of BCOs to stress their importance for all kinds of VLBI data analyses. For our investigations, we concentrate on analyzing data from both legacy networks of the CONT17 campaign. Various aspects of BCOs including their impact on the estimates of geodetically important parameters, such as station coordinates and Earth orientation parameters, are investigated. In addition, some of the theory behind the BCO determination, e.g., the impact of changing the reference clock in the observing network on the BCO estimate is introduced together with the relationship between BCOs and triangle delay closures. In conclusion, missing channels, and here in particular at S band, affecting the ionospheric delay calibration, are identified to be the dominant cause for the occurrence of significant BCOs in VLBI data analysis.
Numéro de notice :	A2021-815
Affiliation des auteurs :	non IGN
Thématique :	POSITIONNEMENT
Nature :	Article
nature-HAL :	ArtAvecCL-RevueIntern
DOI :	10.1007/s00190-021-01579-5
Date de publication en ligne :	01/11/2021
En ligne :	https://doi.org/10.1007/s00190-021-01579-5
Format de la ressource électronique :	URL article
Permalink :	https://documentation.ensg.eu/index.php?lvl=notice_display&id=98896

Ionospheric corrections tailored to the Galileo High Accuracy Service

Ionospheric corrections tailored to the Galileo High Accuracy Service [Article/Communication] / Adria Rovira-Garcia, Auteur ; C.C. Timoté, Auteur ; José Miguel Juan, Auteur ; et al., Auteur . - 2021 . - n° 130.bibliographieLangues : Anglais (eng)in Journal of geodesy > vol 95 n° 12 (December 2021) . - n° 130

Descripteur :	[Vedettes matières IGN] Géodésie spatiale[Termes IGN] correction ionosphérique[Termes IGN] décalage d'horloge[Termes IGN] erreur systématique interfréquence d'horloge[Termes IGN] GalileoSat[Termes IGN] mesurage de phase[Termes IGN] modèle ionosphérique[Termes IGN] positionnement par Galileo[Termes IGN] positionnement ponctuel précis[Termes IGN] résolution d'ambiguïté[Termes IGN] retard ionosphèrique
Résumé :	(auteur) The Galileo High Accuracy Service (HAS) is a new capability of the European Global Navigation Satellite System that is currently under development. The Galileo HAS will start providing satellite orbit and clock corrections (i.e. non-dispersive effects) and soon it will also correct dispersive effects such as inter-frequency biases and, in its full capability, ionospheric delay. We analyse here an ionospheric correction system based on the fast precise point positioning (Fast-PPP) and its potential application to the Galileo HAS. The aim of this contribution is to present some recent upgrades to the Fast-PPP model, with the emphasis on the model geometry and the data used. The results show the benefits of integer ambiguity resolution to obtain unambiguous carrier phase measurements as input to compute the Fast-PPP model. Seven permanent stations are used to assess the errors of the Fast-PPP ionospheric corrections, with baseline distances ranging from 100 to 1000 km from the reference receivers used to compute the Fast-PPP corrections. The 99% of the GPS and Galileo errors in well-sounded areas and in mid-latitude stations are below one total electron content unit. In addition, large errors are bounded by the error prediction of the Fast-PPP model, in the form of the variance of the estimation of the ionospheric corrections. Therefore, we conclude that Fast-PPP is able to provide ionospheric corrections with the required ionospheric accuracy, and realistic confidence bounds, for the Galileo HAS.
Numéro de notice :	A2021-854
Affiliation des auteurs :	non IGN
Thématique :	POSITIONNEMENT
Nature :	Article
nature-HAL :	ArtAvecCL-RevueIntern
DOI :	10.1007/s00190-021-01581-x
Date de publication en ligne :	21/11/2021
En ligne :	https://doi.org/10.1007/s00190-021-01581-x
Format de la ressource électronique :	URL article
Permalink :	https://documentation.ensg.eu/index.php?lvl=notice_display&id=99059

Comparative analysis of real-time precise point positioning method in terms of positioning and zenith tropospheric delay estimation

Comparative analysis of real-time precise point positioning method in terms of positioning and zenith tropospheric delay estimation [Article/Communication] / Omer Faruk Atiz, Auteur ; Salih Alcay, Auteur ; Sermet Ogutcu, Auteur ; Ilkay Bugdayci, Auteur . - 2021 . - pp.bibliographieLangues : Anglais (eng)in Survey review > vol inconnu [24/11/2021] . - pp

Descripteur :	[Vedettes matières IGN] Navigation et positionnement[Termes IGN] analyse comparative[Termes IGN] positionnement ponctuel précis[Termes IGN] retard troposphérique zénithal[Termes IGN] RTKLIB[Termes IGN] temps réel
Résumé :	(auteur) The positioning performance of widely used real-time precise point positioning (RT-PPP) software packages BNC, RTKLIB, and PPP-WIZARD were tested in terms of convergence time and accuracy. The convergence time of PPP-WIZARD solutions is reduced by ambiguity resolution (AR). The GPS + GLONASS + GALILEO (GRE) mode improved the convergence time of GPS + GALILEO (GE) mode by 22.0%, 15.5%, 17.1%, and 11.4% for the BNC, RTKLIB, PPP-WIZARD (AR) and PPP-WIZARD, respectively. For the GRE mode, RMSEs of the BNC, RTKLIB, PPP-WIZARD (AR), and PPP-WIZARD software packages in the horizontal/vertical component are 3.8/5.6, 2.6/6.2, 3.3/6.5, 4.3/7.0 cm, respectively. In comparison with the IGS-ZTD (International GNSS Service ZTD), BNC, RTKLIB, PPP-WIZARD (AR), and PPP-WIZARD solutions show a mean bias of 0.28, −0.72, 2.80, and 2.83 cm, respectively in GE mode. The GRE mode reduced the RMSEs of the ZTD estimations of BNC, RTKLIB, PPP-WIZARD (AR) and PPP-WIZARD by 2.9%, 5.1%, 0.6%, and 0.4% respectively.
Numéro de notice :	A2022-014
Affiliation des auteurs :	non IGN
Thématique :	POSITIONNEMENT
Nature :	Article
DOI :	10.1080/00396265.2021.2001627
Date de publication en ligne :	22/11/2021
En ligne :	https://doi.org/10.1080/00396265.2021.2001627
Format de la ressource électronique :	URL article
Permalink :	https://documentation.ensg.eu/index.php?lvl=notice_display&id=99089

Hourly rainfall forecast model using supervised learning algorithm

Hourly rainfall forecast model using supervised learning algorithm [Article/Communication] / Qingzhi Zhao, Auteur ; Yang Liu, Auteur ; Wanqiang Yao, Auteur ; et al., Auteur . - 2022 . - n° 4100509.bibliographieLangues : Anglais (eng)in IEEE Transactions on geoscience and remote sensing > vol 60 n° 1 (January 2022) . - n° 4100509

Descripteur :	[Vedettes matières IGN] Applications de géodésie spatiale[Termes IGN] autocorrélation[Termes IGN] classification dirigée[Termes IGN] classification par séparateurs à vaste marge[Termes IGN] données GNSS[Termes IGN] heure[Termes IGN] modèle de simulation[Termes IGN] modèle météorologique[Termes IGN] précipitation[Termes IGN] série temporelle[Termes IGN] station GNSS[Termes IGN] Taïwan[Termes IGN] vapeur d'eau
Résumé :	(auteur) Previous studies on short-term rainfall forecast using precipitable water vapor (PWV) and meteorological parameters mainly focus on rain occurrence, while the rainfall forecast is rarely investigated. Therefore, an hourly rainfall forecast (HRF) model based on a supervised learning algorithm is proposed in this study to predict rainfall with high accuracy and time resolution. Hourly PWV derived from Global Navigation Satellite System (GNSS) and temperature data are used as input parameters of the HRF model, and a support vector machine is introduced to train the proposed model. In addition, this model also considers the time autocorrelation of rainfall in the previous epoch. Hourly PWV data of 21 GNSS stations and collocated meteorological parameters (temperature and rainfall) for five years in Taiwan Province are selected to validate the proposed model. Internal and external validation experiments have been performed under the cases of slight, moderate, and heavy rainfall. Average root-mean-square error (RMSE) and relative RMSE of the proposed HRF model are 1.36/1.39 mm/h and 1.00/0.67, respectively. In addition, the proposed HRF model is compared with the similar works in previous studies. Compared results reveal the satisfactory performance and superiority of the proposed HRF model in terms of time resolution and forecast accuracy.
Numéro de notice :	A2022-024
Affiliation des auteurs :	non IGN
Thématique :	POSITIONNEMENT
Nature :	Article
nature-HAL :	ArtAvecCL-RevueIntern
DOI :	10.1109/TGRS.2021.3054582
Date de publication en ligne :	09/02/2021
En ligne :	https://doi.org/10.1109/TGRS.2021.3054582
Format de la ressource électronique :	URL article
Permalink :	https://documentation.ensg.eu/index.php?lvl=notice_display&id=99253

Comparison of atmospheric mass density models using a new data source: COSMIC satellite ephemerides

Comparison of atmospheric mass density models using a new data source: COSMIC satellite ephemerides [Article/Communication] / Yang Yang, Auteur ; Ronald Maj, Auteur ; Changyong He, Auteur ; Robert Norman, Auteur ; Emma Kerr, Auteur ; Brett Anthony Carter, Auteur ; Julie Louise Currie, Auteur ; Steve Gower, Auteur . - 2022.bibliographieLangues : Anglais (eng)in IEEE Aerospace and Electronic Systems Magazine > vol 37 n° inconnu [04/01/2022]

Descripteur :	[Vedettes matières IGN] Géodésie spatiale[Termes IGN] analyse comparative[Termes IGN] atmosphère terrestre[Termes IGN] éphémérides de satellite[Termes IGN] International Reference Ionosphere[Termes IGN] masse d'air[Termes IGN] modèle atmosphérique[Termes IGN] orbite basse[Termes IGN] teneur totale en électrons
Résumé :	(auteur) Atmospheric mass density (AMD) plays a vital role in the drag calculation for space objects in low Earth orbit. Many empirical AMD models have been developed and used for orbit prediction and efforts continue to improve their accuracy in forecasting high-altitude atmospheric conditions. Previous studies have assessed these models at the height of 200 km to 600 km. In this paper, four state-of-the-art AMD models, i.e., MSISE90, MSISE00, JB2008 and DTM2013 are assessed for their orbit prediction (OP) capabilities by using a new data source of COSMIC satellite ephemerides at an orbital height of ~800 km, where the contribution of ions in the total AMD is more significant. A new testing model was developed by accounting for ion contribution based on the International Reference Ionosphere 2016 model, including many more ion species that are not accounted for in other AMD models. In the assessment, two periods of forty days were chosen in 2014-2015 and 2018-2019, representing solar maximum and minimum periods, respectively, to assess four existing AMD models and the proposed model. Thorough analyses were conducted to compare OP results using different AMD models with precise reference ephemerides of COSMIC satellites and based on various space weather indices. It is shown that the proposed model outperforms all other AMD models in terms of OP errors during the solar maximum period. During solar minimum, the drag acceleration is relatively small for COSMIC satellites. Assessment of all AMD models in the orbit prediction process tends to be contaminated by the remaining uncertainty sources, such as solar radiation pressure.
Numéro de notice :	A2022-070
Affiliation des auteurs :	ENSG+Ext (2020- )
Thématique :	POSITIONNEMENT
Nature :	Article
nature-HAL :	ArtAvecCL-RevueIntern
DOI :	10.1109/MAES.2021.3125101
Date de publication en ligne :	20/12/2021
En ligne :	https://doi.org/10.1109/MAES.2021.3125101
Format de la ressource électronique :	URL article
Permalink :	https://documentation.ensg.eu/index.php?lvl=notice_display&id=99376

Co-seismic ionospheric disturbances following the 2016 West Sumatra and 2018 Palu earthquakes from GPS and GLONASS measurements

Co-seismic ionospheric disturbances following the 2016 West Sumatra and 2018 Palu earthquakes from GPS and GLONASS measurements [Article/Communication] / Mokhamad Nur Cahyadi, Auteur ; Buldan Muslim, Auteur ; Danar Guruh Pratomo, Auteur ; et al., Auteur . - 2022 . - n° 401.biliographieLangues : Anglais (eng)in Remote sensing > vol 14 n° 2 (January 2 2022) . - n° 401

Descripteur :	[Vedettes matières IGN] Géodésie spatiale[Termes IGN] déformation verticale de la croute terrestre[Termes IGN] diffusion de Rayleigh[Termes IGN] données GLONASS[Termes IGN] données GNSS[Termes IGN] Indonésie[Termes IGN] onde acoustique[Termes IGN] perturbation ionosphérique[Termes IGN] propagation ionosphérique[Termes IGN] séisme[Termes IGN] Sumatra[Termes IGN] teneur totale en électrons[Termes IGN] tsunami
Résumé :	(auteur) The study of ionospheric disturbances associated with the two large strike-slip earthquakes in Indonesia was investigated, which are West Sumatra on 2 March 2016 (Mw = 7.8), and Palu on 28 September 2018 (Mw = 7.5). The anomalies were observed by measuring co-seismic ionospheric disturbances (CIDs) using the Global Navigation Satellite System (GNSS). The results show positive and negative CIDs polarization changes for the 2016 West Sumatra earthquake, depending on the position of the satellite line-of-sight, while the 2018 Palu earthquake shows negative changes only due to differences in co-seismic vertical crustal displacement. The 2016 West Sumatra earthquake caused uplift and subsidence, while the 2018 Palu earthquake was dominated by subsidence. TEC anomalies occurred about 10 to 15 min after the two earthquakes with amplitude of 2.9 TECU and 0.4 TECU, respectively. The TEC anomaly amplitude was also affected by the magnitude of the earthquake moment. The disturbance signal propagated with a velocity of ~1–1.72 km s−1 for the 2016 West Sumatra earthquake and ~0.97–1.08 km s−1 for the 2018 Palu mainshock earthquake, which are consistent with acoustic waves. The wave also caused an oscillation signal of ∼4 mHz, and their azimuthal asymmetry of propagation confirmed the phenomena in the Southern Hemisphere. The CID signal could be identified at a distance of around 400–1500 km from the epicenter in the southwestern direction.
Numéro de notice :	A2022-103
Affiliation des auteurs :	non IGN
Thématique :	POSITIONNEMENT
Nature :	Article
DOI :	10.3390/rs14020401
Date de publication en ligne :	16/01/2022
En ligne :	https://doi.org/10.3390/rs14020401
Format de la ressource électronique :	URL article
Permalink :	https://documentation.ensg.eu/index.php?lvl=notice_display&id=99571

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IGN

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IGN / ENSG

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2014-2021 IGN

Centre dedocumentation
scientifique