Descripteur
Termes IGN > sciences naturelles > sciences de la Terre et de l'univers > géosciences > géophysique interne
géophysique interneSynonyme(s)physique du globe |
Documents disponibles dans cette catégorie (7098)
Ajouter le résultat dans votre panier
Visionner les documents numériques
Affiner la recherche Interroger des sources externes
Etendre la recherche sur niveau(x) vers le bas
POD of small LEO satellites based on precise real-time MADOCA and SBAS-aided PPP corrections / Amir Allahvirdi-Zadeh in GPS solutions, vol 25 n° 2 (April 2021)
[article]
Titre : POD of small LEO satellites based on precise real-time MADOCA and SBAS-aided PPP corrections Type de document : Article/Communication Auteurs : Amir Allahvirdi-Zadeh, Auteur ; Kan Wang, Auteur ; Ahmed El-Mowafy, Auteur Année de publication : 2021 Article en page(s) : 14 p. Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Techniques orbitales
[Termes IGN] données GNSS
[Termes IGN] horloge du satellite
[Termes IGN] orbite basse
[Termes IGN] orbitographie par GNSS
[Termes IGN] positionnement ponctuel précis
[Termes IGN] temps réelRésumé : (Auteur) For real-time precise orbit determination (POD) of low earth orbit (LEO) satellites, high-accuracy global navigation satellite system (GNSS) orbit and clock products are necessary in real time. Recently, the Japanese multi-GNSS advanced demonstration of orbit and clock analysis precise point positioning (PPP) service and the new generation of the Australian/New Zealand satellite-based augmentation system (SBAS)-aided PPP service provide free and precise GNSS products that are directly broadcast through the navigation and geostationary earth orbit satellites, respectively. With the high quality of both products shown in this study, a 3D accuracy of centimeters can be achieved in the post-processing mode for the reduced-dynamic orbits of small LEO satellites having a duty cycle down to 40% and at sub-dm to dm level for the kinematic orbits. The results show a promising future for high-accuracy real-time POD onboard LEO satellites benefiting from the precise free-of-charge PPP corrections broadcast by navigation systems or SBAS. Numéro de notice : A2021-091 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s10291-020-01078-8 Date de publication en ligne : 11/01/2021 En ligne : https://doi.org/10.1007/s10291-020-01078-8 Format de la ressource électronique : URL Article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=96880
in GPS solutions > vol 25 n° 2 (April 2021) . - 14 p.[article]Precipitable water vapor fusion based on a generalized regression neural network / Bao Zhang in Journal of geodesy, vol 95 n° 4 (April 2021)
[article]
Titre : Precipitable water vapor fusion based on a generalized regression neural network Type de document : Article/Communication Auteurs : Bao Zhang, Auteur ; Yibing Yao, Auteur Année de publication : 2021 Article en page(s) : n° 36 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale
[Termes IGN] Amérique du nord
[Termes IGN] coefficient d'étalonnage
[Termes IGN] coefficient de corrélation
[Termes IGN] données GNSS
[Termes IGN] données météorologiques
[Termes IGN] erreur systématique
[Termes IGN] fusion de données
[Termes IGN] image Aqua-MODIS
[Termes IGN] image Terra-MODIS
[Termes IGN] précipitation
[Termes IGN] prévision météorologique
[Termes IGN] régression
[Termes IGN] réseau neuronal artificiel
[Termes IGN] vapeur d'eau
[Termes IGN] variation temporelleRésumé : (auteur) Water vapor plays an important role in Earth’s weather and climate processes and energy transfer. Plenty of techniques have developed to monitor precipitable water vapor (PWV), but joint use of different techniques has some problems, including systematic biases, different spatiotemporal coverages and resolutions among different datasets. To address the above problems and improve the data utilization, we propose to use a generalized regression neural network (GRNN) to fuse PWVs from Global Navigation Satellite System (GNSS), Moderate-Resolution Imaging Spectroradiometer (MODIS), and European Centre for Medium‐Range Weather Forecasts Reanalysis 5 (ERA5). The core idea of this method is to use the high-quality GNSS PWV to calibrate and optimize the relatively low-quality MODIS and ERA5 PWV through the constructed GRNNs. Using the proposed method, we generated more than 400 PWV maps that combine GNSS, MODIS, and ERA5 PWVs in North America in 2018. Results show that the overall bias, standard deviation (STD), and root-mean-square (RMS) error are 0.0 mm, 2.1 mm, and 2.2 mm for the improved MODIS PWV, and 0.0 mm, 1.6 mm, and 1.6 mm for the improved ERA5 PWV. Compared to the original MODIS and ERA5 PWV, the total improvements are 37.1% and 15.8% in terms of RMS. The RMS improvements are mainly contributed from the calibration of bias for the MODIS PWV and optimization for the ERA5 PWV. It also demonstrates that the original MODIS PWV tends to be greater than the GNSS PWV while the ERA5 PWV has very small biases. After calibration and optimization, the correlation coefficients between the modified PWV and the GNSS PWV are 0.96 for the MODIS PWV and 0.98 for the ERA5 PWV. The proposed method also diminishes the temporal and spatial variations in accuracy, generating homogeneous PWV products. Since the biases among the three datasets are well removed and data accuracies are improved to the same level, they are thus easily fused and jointly used. Numéro de notice : A2021-259 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-021-01482-z Date de publication en ligne : 01/03/2021 En ligne : https://doi.org/10.1007/s00190-021-01482-z Format de la ressource électronique : url article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=97299
in Journal of geodesy > vol 95 n° 4 (April 2021) . - n° 36[article]Shoreline changes along Northern Ibaraki Coast after the great East Japan earthquake of 2011 / Quang Nguyen Hao in Remote sensing, vol 13 n° 7 (April-1 2021)
[article]
Titre : Shoreline changes along Northern Ibaraki Coast after the great East Japan earthquake of 2011 Type de document : Article/Communication Auteurs : Quang Nguyen Hao, Auteur ; Satoshi Takewaka, Auteur Année de publication : 2021 Article en page(s) : n° 1399 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de télédétection
[Termes IGN] détection de changement
[Termes IGN] effondrement de terrain
[Termes IGN] image ALOS-AVNIR2
[Termes IGN] image proche infrarouge
[Termes IGN] image Sentinel-MSI
[Termes IGN] image Terra-ASTER
[Termes IGN] Japon
[Termes IGN] Normalized Difference Water Index
[Termes IGN] séisme
[Termes IGN] surveillance du littoral
[Termes IGN] trait de côteRésumé : (auteur) In this study, we analyze the influence of the Great East Japan Earthquake, which occurred on 11 March 2011, on the shoreline of the northern Ibaraki Coast. After the earthquake, the area experienced subsidence of approximately 0.4 m. Shoreline changes at eight sandy beaches along the coast are estimated using various satellite images, including the ASTER (Advanced Spaceborne Thermal Emission and Reflection Radiometer), ALOS AVNIR-2 (Advanced Land Observing Satellite, Advanced Visible and Near-infrared Radiometer type 2), and Sentinel-2 (a multispectral sensor). Before the earthquake (for the period March 2001–January 2011), even though fluctuations in the shoreline position were observed, shorelines were quite stable, with the averaged change rates in the range of ±1.5 m/year. The shoreline suddenly retreated due to the earthquake by 20–40 m. Generally, the amount of retreat shows a strong correlation with the amount of land subsidence caused by the earthquake, and a moderate correlation with tsunami run-up height. The ground started to uplift gradually after the sudden subsidence, and shoreline positions advanced accordingly. The recovery speed of the beaches varied from +2.6 m/year to +6.6 m/year, depending on the beach conditions. Numéro de notice : A2021-351 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article DOI : 10.3390/rs13071399 Date de publication en ligne : 05/04/2021 En ligne : https://doi.org/10.3390/rs13071399 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=97601
in Remote sensing > vol 13 n° 7 (April-1 2021) . - n° 1399[article]Strategy for the realisation of the International Height Reference System (IHRS) / Laura Sánchez in Journal of geodesy, vol 95 n° 4 (April 2021)
[article]
Titre : Strategy for the realisation of the International Height Reference System (IHRS) Type de document : Article/Communication Auteurs : Laura Sánchez, Auteur ; Jonas Ågren, Auteur ; Jianliang Huang, Auteur ; et al., Auteur Année de publication : 2021 Article en page(s) : n° 33 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Systèmes de référence et réseaux
[Termes IGN] Association internationale de géodésie
[Termes IGN] champ de pesanteur terrestre
[Termes IGN] coordonnées géodésiques
[Termes IGN] hauteur ellipsoïdale
[Termes IGN] International Terrestrial Reference Frame
[Termes IGN] modèle de géopotentiel
[Termes IGN] norme
[Termes IGN] potentiel de pesanteur terrestre
[Termes IGN] système de référence altimétrique
[Termes IGN] système international de référence altimétriqueRésumé : (auteur) In 2015, the International Association of Geodesy defined the International Height Reference System (IHRS) as the conventional gravity field-related global height system. The IHRS is a geopotential reference system co-rotating with the Earth. Coordinates of points or objects close to or on the Earth’s surface are given by geopotential numbers C(P) referring to an equipotential surface defined by the conventional value W0 = 62,636,853.4 m2 s−2, and geocentric Cartesian coordinates X referring to the International Terrestrial Reference System (ITRS). Current efforts concentrate on an accurate, consistent, and well-defined realisation of the IHRS to provide an international standard for the precise determination of physical coordinates worldwide. Accordingly, this study focuses on the strategy for the realisation of the IHRS; i.e. the establishment of the International Height Reference Frame (IHRF). Four main aspects are considered: (1) methods for the determination of IHRF physical coordinates; (2) standards and conventions needed to ensure consistency between the definition and the realisation of the reference system; (3) criteria for the IHRF reference network design and station selection; and (4) operational infrastructure to guarantee a reliable and long-term sustainability of the IHRF. A highlight of this work is the evaluation of different approaches for the determination and accuracy assessment of IHRF coordinates based on the existing resources, namely (1) global gravity models of high resolution, (2) precise regional gravity field modelling, and (3) vertical datum unification of the local height systems into the IHRF. After a detailed discussion of the advantages, current limitations, and possibilities of improvement in the coordinate determination using these options, we define a strategy for the establishment of the IHRF including data requirements, a set of minimum standards/conventions for the determination of potential coordinates, a first IHRF reference network configuration, and a proposal to create a component of the International Gravity Field Service (IGFS) dedicated to the maintenance and servicing of the IHRS/IHRF. Numéro de notice : A2021-260 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-021-01481-0 Date de publication en ligne : 22/02/2021 En ligne : https://doi.org/10.1007/s00190-021-01481-0 Format de la ressource électronique : url article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=97300
in Journal of geodesy > vol 95 n° 4 (April 2021) . - n° 33[article]Are pine-oak mixed stands in Mediterranean mountains more resilient to drought than their monospecific counterparts? / Francisco J. Muñoz-Gálvez in Forest ecology and management, vol 484 ([15/03/2021])
[article]
Titre : Are pine-oak mixed stands in Mediterranean mountains more resilient to drought than their monospecific counterparts? Type de document : Article/Communication Auteurs : Francisco J. Muñoz-Gálvez, Auteur ; Asier Herrero, Auteur ; Maria Esther Pérez-Corona, Auteur ; et al., Auteur Année de publication : 2021 Article en page(s) : n° 118955 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Termes IGN] analyse comparative
[Termes IGN] changement climatique
[Termes IGN] croissance des arbres
[Termes IGN] Espagne
[Termes IGN] forêt méditerranéenne
[Termes IGN] gestion forestière
[Termes IGN] module linéaire
[Termes IGN] peuplement mélangé
[Termes IGN] Pinus sylvestris
[Termes IGN] Quercus pyrenaica
[Termes IGN] sécheresse
[Termes IGN] service écosystémique
[Termes IGN] vulnérabilité
[Vedettes matières IGN] Végétation et changement climatiqueRésumé : (auteur) Climate change projections point to an increase in the intensity and frequency of extreme drought events with important negative impacts on forest functioning. Predicting these impacts constitutes a crucial challenge for forest managers and for the maintenance of ecosystem services supply. Promoting mixed stands seems a promising strategy for adapting forest ecosystems to ongoing climate change. However, some uncertainty exists regarding whether admixture can improve growth resilience to extreme drought events. Here, we aim to assess tree growth response to drought in mixed and monospecific stands of Pinus sylvestris L. and Quercus pyrenaica Willd. in central Spain. We built tree-ring chronologies and evaluated tree growth sensitivity to water availability and growth resilience components to extreme droughts using linear mixed models. We found contrasting species- and climate-specific responses to admixture. Q. pyrenaica growth was significantly higher in mixed than in monospecific stands, especially in years without water limitations, while P. sylvestris showed higher growth in mixed stands under dry conditions. However, our results showed a species-specific trade-off between resistance and recovery. While P. sylvestris showed higher resistance but lower recovery to drought events in mixed than monospecific stands, Q. pyrenaica showed higher recovery but lower resistance. This trade-off might explain the absence of admixture effects on species resilience. Our results highlight the importance of considering species-specific responses to water availability and associated trade-offs when evaluating admixture effects on drought vulnerability. Overall, we show a positive effect of admixture on the long-term growth stability in response to average climate conditions, but no effects in short-term resilience capacity to increasingly common extreme dry conditions. Consequently, admixture can promote forest productivity stability but should be carefully considered as a management solution for promoting the resilience of Mediterranean mountain forests to increasing aridity. Numéro de notice : A2021-264 Affiliation des auteurs : non IGN Thématique : FORET Nature : Article DOI : 10.1016/j.foreco.2021.118955 Date de publication en ligne : 25/01/2021 En ligne : https://doi.org/10.1016/j.foreco.2021.118955 Format de la ressource électronique : url article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=97316
in Forest ecology and management > vol 484 [15/03/2021] . - n° 118955[article]GIS-based spatial landslide distribution analysis of district Neelum, AJ&K, Pakistan / Shah Naseer in Natural Hazards, vol 106 n° 1 (March 2021)PermalinkIntegrity investigation of global ionospheric TEC maps for high-precision positioning / Jiaojiao Zhao in Journal of geodesy, vol 95 n° 3 (March 2021)PermalinkMachine learning in ground motion prediction / Farid Khosravikia in Computers & geosciences, vol 148 (March 2021)PermalinkMitigating high latitude ionospheric scintillation effects on GNSS Precise Point Positioning exploiting 1-s scintillation indices / Kai Guo in Journal of geodesy, vol 95 n° 3 (March 2021)PermalinkModélisation des délais ionosphériques appliquée au traitement PPP-RTK centimétrique avec ambiguïtés entières de phase / Camille Parra in XYZ, n° 166 (mars 2021)PermalinkLe nivellement par GNSS chez SNCF Réseau / Antoine Beuvain Pacheco in XYZ, n° 166 (mars 2021)PermalinkUne nouvelle détermination de l'altitude de l'Everest par le Népal et la Chine / Gavin Schrock in XYZ, n° 166 (mars 2021)PermalinkON GLONASS pseudo-range inter-frequency bias solution with ionospheric delay modeling and the undifferenced uncombined PPP / Zheng Zhang in Journal of geodesy, vol 95 n° 3 (March 2021)PermalinkPassive radar imaging of ship targets with GNSS signals of opportunity / Debora Pastina in IEEE Transactions on geoscience and remote sensing, Vol 59 n° 3 (March 2021)PermalinkThe Realization and evaluation of PPP ambiguity resolution with INS aiding in marine survey / Zhenqiang Du in Marine geodesy, vol 44 n° 2 (March 2021)PermalinkWhat have we learnt from Icesat on Greenland ice sheet change and what to expect from Icesat 2 / Blaženka Bukač in Geodetski vestnik, vol 65 n° 1 (March - May 2021)PermalinkAssessment of mass-induced sea level variability in the Tropical Indian Ocean based on GRACE and altimeter observations / Shiva Shankar Manche in Journal of geodesy, vol 95 n° 2 (February 2021)PermalinkEarthquake sensitivity to tides and seasons: theoretical studies / François Pétrélis in Journal of Statistical Mechanics: Theory and Experiment, vol 2021 n° 2 (February 2021)PermalinkA GIS-based system for spatial-temporal availability evaluation of the open spaces used as emergency shelters: The case of Victoria, British Columbia, Canada / Yibing Yao in ISPRS International journal of geo-information, vol 10 n° 2 (February 2021)PermalinkIWV retrieval from ground GNSS receivers during NAWDEX / Pierre Bosser in Advances in geosciences, vol 55 ([01/02/2021])PermalinkPerformance of 6 different global navigation satellite system receivers at low latitude under moderate and strong scintillation / E.R. de Paula in Earth and space science, vol 8 n° 2 (February 2021)PermalinkA practical method for calculating reliable integer float estimator in GNSS precise positioning / Xianwen Yu in Survey review, Vol 53 n° 377 (February 2021)PermalinkReceiver DCB analysis and calibration in geomagnetic storm-time using IGS products / Jianfeng Li in Survey review, Vol 53 n° 377 (February 2021)PermalinkStochastic model reliability in GNSS baseline solution / Aviram Borko in Journal of geodesy, vol 95 n° 2 (February 2021)PermalinkUsing automated vegetation cover estimation from close-range photogrammetric point clouds to compare vegetation location properties in mountain terrain / R. Niederheiser in GIScience and remote sensing, vol 58 n° 1 (February 2021)Permalink