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Ionospheric error contribution to GNSS single-frequency navigation at the 2014 solar maximum / Raul Orus Perez in Journal of geodesy, vol 91 n° 4 (April 2017)
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Titre : Ionospheric error contribution to GNSS single-frequency navigation at the 2014 solar maximum Type de document : Article/Communication Auteurs : Raul Orus Perez, Auteur Année de publication : 2017 Article en page(s) : pp 397 - 407 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Termes IGN] correction ionosphérique
[Termes IGN] éruption solaire
[Termes IGN] International GNSS Service
[Termes IGN] International Reference Ionosphere
[Termes IGN] modèle ionosphérique
[Termes IGN] récepteur bifréquence
[Termes IGN] récepteur monofréquence
[Termes IGN] retard ionosphèrique
[Termes IGN] signal Galileo
[Termes IGN] signal GPS
[Vedettes matières IGN] Traitement de données GNSSRésumé : (auteur) For single-frequency users of the global satellite navigation system (GNSS), one of the main error contributors is the ionospheric delay, which impacts the received signals. As is well-known, GPS and Galileo transmit global models to correct the ionospheric delay, while the international GNSS service (IGS) computes precise post-process global ionospheric maps (GIM) that are considered reference ionospheres. Moreover, accurate ionospheric maps have been recently introduced, which allow for the fast convergence of the real-time precise point position (PPP) globally. Therefore, testing of the ionospheric models is a key issue for code-based single-frequency users, which constitute the main user segment. Therefore, the testing proposed in this paper is straightforward and uses the PPP modeling applied to single- and dual-frequency code observations worldwide for 2014. The usage of PPP modeling allows us to quantify—for dual-frequency users—the degradation of the navigation solutions caused by noise and multipath with respect to the different ionospheric modeling solutions, and allows us, in turn, to obtain an independent assessment of the ionospheric models. Compared to the dual-frequency solutions, the GPS and Galileo ionospheric models present worse global performance, with horizontal root mean square (RMS) differences of 1.04 and 0.49 m and vertical RMS differences of 0.83 and 0.40 m, respectively. While very precise global ionospheric models can improve the dual-frequency solution globally, resulting in a horizontal RMS difference of 0.60 m and a vertical RMS difference of 0.74 m, they exhibit a strong dependence on the geographical location and ionospheric activity. Numéro de notice : A2017-106 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-016-0971-0 En ligne : http://dx.doi.org/10.1007/s00190-016-0971-0 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=84496
in Journal of geodesy > vol 91 n° 4 (April 2017) . - pp 397 - 407[article]Ionospheric tomography based on GNSS observations of the CMONOC: performance in the topside ionosphere / Zhe Yang in GPS solutions, vol 21 n° 2 (April 2017)
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Titre : Ionospheric tomography based on GNSS observations of the CMONOC: performance in the topside ionosphere Type de document : Article/Communication Auteurs : Zhe Yang, Auteur ; Shuli Song, Auteur ; Wenhai Jiao, Auteur ; et al., Auteur Année de publication : 2017 Article en page(s) : pp 363 – 375 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale
[Termes IGN] Chine
[Termes IGN] données localisées 3D
[Termes IGN] ionosphère
[Termes IGN] propagation ionosphérique
[Termes IGN] station GNSS
[Termes IGN] tomographie par GPS
[Termes IGN] voxelRésumé : (auteur) This study carries out a quantitative analysis of the performance of ionospheric tomography in the topside ionosphere, utilizing data of October 2011 collected from 260 Global Navigation Satellite System (GNSS) stations in the Crustal Movement Observation Network of China. This tomographic reconstruction with a resolution of 2° in latitude, 2° in longitude and 20 km in altitude has more than 70 % of voxels traversed by GPS raypaths and is able to provide reliable bottom parts of ionospheric profiles. Compared with the observations measured by the Defense Meteorological Satellite Program (DMSP) satellites (F16, F17 and F18) at an altitude of 830–880 km, the results show that there is an overestimation in the reconstructed plasma density at the DMSP altitude, and the reconstruction is better during daytime than nighttime. In addition, the reconstruction at nighttime also indicates a solar activity and latitudinal dependence. In summary, with respect to DMSP measurements, the daytime bias is on average from −0.32 × 105/cm3 to −0.28 × 105/cm3, while the nighttime bias is between −0.37 × 105/cm3 and −0.24 × 105/cm3, and the standard deviation at daytime and at nighttime is, respectively, 0.082 × 105/cm3 to 0.244 × 105/cm3 and 0.086 × 105/cm3 to 0.428 × 105/cm3. This study suggests that vertical ionospheric profiles from other sources, such as ionosondes or GNSS occultation satellites, should be incorporated into ground-based GNSS topside tomographic studies. Numéro de notice : A2017-212 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.1007/s10291-016-0526-0 En ligne : http://dx.doi.org/10.1007/s10291-016-0526-0 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=85054
in GPS solutions > vol 21 n° 2 (April 2017) . - pp 363 – 375[article]Performance evaluation of GNSS-TEC estimation techniques at the grid point in middle and low latitudes during different geomagnetic conditions / O. E. Abe in Journal of geodesy, vol 91 n° 4 (April 2017)
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Titre : Performance evaluation of GNSS-TEC estimation techniques at the grid point in middle and low latitudes during different geomagnetic conditions Type de document : Article/Communication Auteurs : O. E. Abe, Auteur ; X. Otero Villamide, Auteur ; C. Paparini, Auteur ; et al., Auteur Année de publication : 2017 Article en page(s) : pp 409 - 417 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale
[Termes IGN] champ géomagnétique
[Termes IGN] erreur systématique
[Termes IGN] Espagne
[Termes IGN] estimation statistique
[Termes IGN] étalonnage
[Termes IGN] évaluation
[Termes IGN] Ghana
[Termes IGN] latitude
[Termes IGN] performance
[Termes IGN] signal GNSS
[Termes IGN] teneur totale en électrons
[Termes IGN] traitement du signalRésumé : (auteur) Global Navigation Satellite Systems (GNSS) have become a powerful tool use in surveying and mapping, air and maritime navigation, ionospheric/space weather research and other applications. However, in some cases, its maximum efficiency could not be attained due to some uncorrelated errors associated with the system measurements, which is caused mainly by the dispersive nature of the ionosphere. Ionosphere has been represented using the total number of electrons along the signal path at a particular height known as Total Electron Content (TEC). However, there are many methods to estimate TEC but the outputs are not uniform, which could be due to the peculiarity in characterizing the biases inside the observables (measurements), and sometimes could be associated to the influence of mapping function. The errors in TEC estimation could lead to wrong conclusion and this could be more critical in case of safety-of-life application. This work investigated the performance of Ciraolo’s and Gopi’s GNSS-TEC calibration techniques, during 5 geomagnetic quiet and disturbed conditions in the month of October 2013, at the grid points located in low and middle latitudes. The data used are obtained from the GNSS ground-based receivers located at Borriana in Spain (40∘N, 0∘E; mid latitude) and Accra in Ghana (5.50∘N, −0.20∘E; low latitude). The results of the calibrated TEC are compared with the TEC obtained from European Geostationary Navigation Overlay System Processing Set (EGNOS PS) TEC algorithm, which is considered as a reference data. The TEC derived from Global Ionospheric Maps (GIM) through International GNSS service (IGS) was also examined at the same grid points. The results obtained in this work showed that Ciraolo’s calibration technique (a calibration technique based on carrier-phase measurements only) estimates TEC better at middle latitude in comparison to Gopi’s technique (a calibration technique based on code and carrier-phase measurements). At the same time, Gopi’s calibration was also found more reliable in low latitude than Ciraolo’s technique. In addition, the TEC derived from IGS GIM seems to be much reliable in middle-latitude than in low-latitude region. Numéro de notice : A2017-107 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-016-0972-z En ligne : http://dx.doi.org/10.1007/s00190-016-0972-z Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=84497
in Journal of geodesy > vol 91 n° 4 (April 2017) . - pp 409 - 417[article]Radial growth resilience of sessile oak after drought is affected by site water status, stand density, and social status / Raphaël Trouvé in Trees, vol 31 n° 2 (April 2017)
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Titre : Radial growth resilience of sessile oak after drought is affected by site water status, stand density, and social status Type de document : Article/Communication Auteurs : Raphaël Trouvé, Auteur ; Jean-Daniel Bontemps , Auteur ; Catherine Collet, Auteur ; Ingrid Seynave, Auteur ; François Lebourgeois, Auteur
Année de publication : 2017 Projets : ORACLE/Changements Environnementaux Planétaires & Sociétés (CEP&S) / Noblet-Ducoudré, Nathalie de Article en page(s) : pp 517 - 529 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Termes IGN] croissance des arbres
[Termes IGN] densité de la végétation
[Termes IGN] Quercus sessiliflora
[Termes IGN] résilience écologique
[Termes IGN] sécheresseRésumé : (auteur) Ongoing climate change will drive more frequent drought events in the future, with potential impacts on tree community structure and functioning. Growth responses of tree communities may depend on their past water status and on competition pressure. We investigated the effects of site water status, population density, and tree social status on tree growth resistance and resilience following the severe drought of 1976 in even-aged stands of sessile oak (Quercus petraea). We used retrospective growth data collected in permanent plots experiencing contrasted climatic and stand density conditions. We used boosted regression trees to calibrate a tree growth model over 1960–1975, which was then used to provide a baseline of expected tree growth following 1976. Growth dynamics during and after 1976 was examined using the ratio between observed and expected growths over 1976–1983. Tree radial growth was on average 0.6 times its expected values in 1976 and was still 0.63 times its expected value in 1977. Despite experiencing higher summer soil water deficit in 1976, trees growing in drier sites exhibited remarkably faster growth recovery than those in moister sites. Suppressed trees grown in higher density stands recovered their normal growth rate slower than dominant trees. Forest growth is evidenced to be more vulnerable to drought in moister than in drier sites. Competitive pressures also alter tree capacity to recover from a severe drought, accelerating suppression of smaller trees in high-density stands. These results highlight the role of acclimation and selection processes in tree community responses to present and future climates. Numéro de notice : A2017-874 Affiliation des auteurs : LIF+Ext (2012-2019) Thématique : FORET Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00468-016-1479-1 Date de publication en ligne : 21/10/2016 En ligne : https://doi.org/10.1007/s00468-016-1479-1 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=90996
in Trees > vol 31 n° 2 (April 2017) . - pp 517 - 529[article]Spatiotemporal downscaling approaches for monitoring 8-day 30 m actual evapotranspiration / Yinghai Ke in ISPRS Journal of photogrammetry and remote sensing, vol 126 (April 2017)
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Titre : Spatiotemporal downscaling approaches for monitoring 8-day 30 m actual evapotranspiration Type de document : Article/Communication Auteurs : Yinghai Ke, Auteur ; Jungho Im, Auteur ; Seonyoung Park, Auteur ; Huili Gong, Auteur Année de publication : 2017 Article en page(s) : pp 79 – 93 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image optique
[Termes IGN] analyse diachronique
[Termes IGN] apprentissage automatique
[Termes IGN] classification par forêts d'arbres décisionnels
[Termes IGN] évapotranspiration
[Termes IGN] image à haute résolution
[Termes IGN] image Terra-MODIS
[Termes IGN] indice de végétation
[Termes IGN] réflectance de surface
[Termes IGN] ressources en eau
[Termes IGN] température au solRésumé : (auteur) Continuous monitoring of actual evapotranspiration (ET) is critical for water resources management at both regional and local scales. Although the MODIS ET product (MOD16A2) provides viable sources for ET monitoring at 8-day intervals, the spatial resolution (1 km) is too coarse for local scale applications. In this study, we propose a machine learning and spatial temporal fusion (STF)-integrated approach in order to generate 8-day 30 m ET based on both MOD16A2 and Landsat 8 data with three schemes. Random forest machine learning was used to downscale MODIS 1 km ET to 30 m resolution based on nine Landsat-derived indicators including vegetation indices (VIs) and land surface temperature (LST). STF-based models including Spatial and Temporal Adaptive Reflectance Fusion Model and Spatio-Temporal Image Fusion Model were used to derive synthetic Landsat surface reflectance (scheme 1)/VIs (scheme 2)/ET (scheme 3) on Landsat-unavailable dates. The approach was tested over two study sites in the United States. The results showed that fusion of Landsat VIs produced the best accuracy of predicted ET (R2 = 0.52–0.97, RMSE = 0.47–3.0 mm/8 days and rRMSE = 6.4–37%). High density of cloud-clear Landsat image acquisitions and low spatial heterogeneity of Landsat VIs benefit the ET prediction. The downscaled 30 m ET had good agreement with MODIS ET (RMSE = 0.42–3.4 mm/8 days, rRMSE = 3.2–26%). Comparison with the in situ ET measurements showed that the downscaled ET had higher accuracy than MODIS ET. Numéro de notice : A2017-114 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.isprsjprs.2017.02.006 En ligne : http://dx.doi.org/10.1016/j.isprsjprs.2017.02.006 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=84509
in ISPRS Journal of photogrammetry and remote sensing > vol 126 (April 2017) . - pp 79 – 93[article]Exemplaires(3)
Code-barres Cote Support Localisation Section Disponibilité 081-2017041 RAB Revue Centre de documentation En réserve L003 Disponible 081-2017043 DEP-EXM Revue LASTIG Dépôt en unité Exclu du prêt 081-2017042 DEP-EAF Revue Nancy Dépôt en unité Exclu du prêt Statistical atmospheric parameter retrieval largely benefits from spatial–spectral image compression / Joaquín García-Sobrino in IEEE Transactions on geoscience and remote sensing, vol 55 n° 4 (April 2017)
PermalinkEvaluation des ressources forestières pour la bioéconomie : quels nouveaux besoins et comment y répondre ? / Jean-Christophe Hervé in Innovations Agronomiques, vol 56 (Mars 2017)
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PermalinkA participatory framework for developing public participation GIS solutions to improve resource management systems / Nagesh Kolagani in International journal of geographical information science IJGIS, vol 31 n° 3-4 (March-April 2017)
PermalinkGPS - Zenith Total Delay assimilation in different resolution simulations of a heavy precipitation event over southern France / Alberto Caldas-Álvarez in Advances in Science and Research, vol 14 (2017)
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PermalinkAcceleration of the global coastal sea level rise during the 20th century re-evaluated / Huseyin Baki Iz in Journal of geodetic science, vol 7 n° 1 (February 2017)
PermalinkCharacterizing the relationship between land use land cover change and land surface temperature / Duy X. Tran in ISPRS Journal of photogrammetry and remote sensing, vol 124 (February 2017)
PermalinkClimatic microrefugia under anthropogenic climate change: implications for species redistribution / Jonathan Lenoir in Ecography, vol 40 n° 2 (February 2017)
PermalinkPulse compression waveform and filter optimization for spaceborne cloud and precipitation radar / Robert M. Beauchamp in IEEE Transactions on geoscience and remote sensing, vol 55 n° 2 (February 2017)
PermalinkTropospheric refractivity and zenith path delays from least-squares collocation of meteorological and GNSS data / Karina Wilgan in Journal of geodesy, vol 91 n° 2 (February 2017)
PermalinkClimatic niche breadth can explain variation in geographical range size of alpine and subalpine plants / Fangyuan Yu in International journal of geographical information science IJGIS, vol 31 n° 1-2 (January - February 2017)
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