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Tsunami-wave parameter estimation using GNSS-based sea surface height measurement / Kegen Yu in IEEE Transactions on geoscience and remote sensing, vol 53 n° 5 (mai 2015)
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Titre : Tsunami-wave parameter estimation using GNSS-based sea surface height measurement Type de document : Article/Communication Auteurs : Kegen Yu, Auteur Année de publication : 2015 Article en page(s) : pp 2603 - 2611 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale
[Termes IGN] données GNSS
[Termes IGN] estimation des paramètres
[Termes IGN] hauteurs de mer
[Termes IGN] longueur d'onde
[Termes IGN] réflectométrie par GNSS
[Termes IGN] simulation
[Termes IGN] traitement de données GNSS
[Termes IGN] tsunami
[Termes IGN] vagueRésumé : (auteur) This paper focuses on the estimation of tsunami-wave parameters (propagation direction, propagation speed, and wavelength) using the Global Navigation Satellite System (GNSS) reflectometry (GNSS-R)-based sea surface height (SSH) measurements. By exploiting multiple surface specular reflection tracks of GNSS signals as well as the geometry of wave propagation direction and the multiple tracks, concise mathematical expressions are derived to determine the propagation direction and speed and wavelength of a tsunami wave. Real tsunami-wave data measured by buoy sensors are employed to model GNSS-R-based SSH measurements by adding Gaussian measurement noise. The simulation results demonstrate that the proposed method can achieve a propagation direction estimation accuracy of about 4.4° and 5.9° when the SSH error standard deviations are 10 and 20 cm, respectively. The propagation speed estimation accuracies are about 12.7 and 17.7 m/s, respectively, under the same conditions when the speed ground truth is 200 m/s. The results also show that the wavelength estimation error can be as large as 100 km when the wavelength ground truth is about 400 km. Better filtering methods are needed to improve the wavelength estimation accuracy by mitigating the effect of the SSH estimation error particularly on the wave trailing edge of small negative magnitudes. Numéro de notice : A2015-632 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1109/TGRS.2014.2362113 En ligne : https://doi.org/10.1109/TGRS.2014.2362113 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=78120
in IEEE Transactions on geoscience and remote sensing > vol 53 n° 5 (mai 2015) . - pp 2603 - 2611[article]Exemplaires(1)
Code-barres Cote Support Localisation Section Disponibilité 065-2015051 RAB Revue Centre de documentation En réserve L003 Disponible An alternative ionospheric correction model for global navigation satellite systems / M.M. Hoque in Journal of geodesy, vol 89 n° 4 (April 2015)
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Titre : An alternative ionospheric correction model for global navigation satellite systems Type de document : Article/Communication Auteurs : M.M. Hoque, Auteur ; Norbert Jakowski, Auteur Année de publication : 2015 Article en page(s) : pp 391 - 406 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale
[Termes IGN] correction ionosphérique
[Termes IGN] ionosphère
[Termes IGN] modèle ionosphérique
[Termes IGN] propagation ionosphériqueRésumé : (auteur) The ionosphere is recognized as a major error source for single-frequency operations of global navigation satellite systems (GNSS). To enhance single-frequency operations the global positioning system (GPS) uses an ionospheric correction algorithm (ICA) driven by 8 coefficients broadcasted in the navigation message every 24 h. Similarly, the global navigation satellite system Galileo uses the electron density NeQuick model for ionospheric correction. The Galileo satellite vehicles (SVs) transmit 3 ionospheric correction coefficients as driver parameters of the NeQuick model. In the present work, we propose an alternative ionospheric correction algorithm called Neustrelitz TEC broadcast model NTCM-BC that is also applicable for global satellite navigation systems. Like the GPS ICA or Galileo NeQuick, the NTCM-BC can be optimized on a daily basis by utilizing GNSS data obtained at the previous day at monitor stations. To drive the NTCM-BC, 9 ionospheric correction coefficients need to be uploaded to the SVs for broadcasting in the navigation message. Our investigation using GPS data of about 200 worldwide ground stations shows that the 24-h-ahead prediction performance of the NTCM-BC is better than the GPS ICA and comparable to the Galileo NeQuick model. We have found that the 95 percentiles of the prediction error are about 16.1, 16.1 and 13.4 TECU for the GPS ICA, Galileo NeQuick and NTCM-BC, respectively, during a selected quiet ionospheric period, whereas the corresponding numbers are found about 40.5, 28.2 and 26.5 TECU during a selected geomagnetic perturbed period. However, in terms of complexity the NTCM-BC is easier to handle than the Galileo NeQuick and in this respect comparable to the GPS ICA. Numéro de notice : A2015-344 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-014-0783-z Date de publication en ligne : 13/12/2014 En ligne : https://doi.org/10.1007/s00190-014-0783-z Format de la ressource électronique : URL Article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=76716
in Journal of geodesy > vol 89 n° 4 (April 2015) . - pp 391 - 406[article]Carrier-phase ambiguity resolution: Handling the biases for improved triple-frequency PPP convergence / Denis Laurichesse in GPS world, vol 26 n° 4 (April 2015)
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Titre : Carrier-phase ambiguity resolution: Handling the biases for improved triple-frequency PPP convergence Type de document : Article/Communication Auteurs : Denis Laurichesse, Auteur Année de publication : 2015 Article en page(s) : pp 42 - 49 Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale
[Termes IGN] convergence
[Termes IGN] erreur systématique
[Termes IGN] onde porteuse
[Termes IGN] phase
[Termes IGN] phase GPS
[Termes IGN] positionnement différentiel
[Termes IGN] positionnement ponctuel précis
[Termes IGN] récepteur trifréquence
[Termes IGN] résolution d'ambiguïtéRésumé : (éditeur) [...] The other precision of PPP is its use of carrier-phase measurements rather than just pseudoranges. Carrier-phase measurements have a precision on the order of two magnitudes (a factor of 100) better than that of pseudoranges. But there is a catch to the use of carrier-phase measurements: they are ambiguous by an integer multiple of one cycle. Processing algorithms must resolve the value of this ambiguity and ideally fix it at its correct integer value. Unfortunately, it is difficult to do this instantaneously, and often many epochs of measurements are needed for a position solution to converge to a sufficiently high accuracy, say better than 10 centimeters. Researchers are actively working on reducing the convergence time, and this month'column, we look at how using measurements from three satellite frequencies rather than just two can help. Numéro de notice : A2015-092 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : sans En ligne : http://gpsworld.com/innovation-carrier-phase-ambiguity-resolution/ Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=75588
in GPS world > vol 26 n° 4 (April 2015) . - pp 42 - 49[article]Exemplaires(1)
Code-barres Cote Support Localisation Section Disponibilité 067-2015041 RAB Revue Centre de documentation En réserve L003 Disponible Evaluating leaf chlorophyll content prediction from multispectral remote sensing data within a physically-based modelling framework / H. Croft in ISPRS Journal of photogrammetry and remote sensing, vol 102 (April 2015)
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Titre : Evaluating leaf chlorophyll content prediction from multispectral remote sensing data within a physically-based modelling framework Type de document : Article/Communication Auteurs : H. Croft, Auteur ; Jing M. Chen, Auteur ; Y. Zhang, Auteur ; et al., Auteur Année de publication : 2015 Article en page(s) : pp 85 - 95 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image optique
[Termes IGN] Acer saccharum
[Termes IGN] aiguille
[Termes IGN] image Landsat-TM
[Termes IGN] indice de stress
[Termes IGN] Leaf Area Index
[Termes IGN] modèle de transfert radiatif
[Termes IGN] Picea mariana
[Termes IGN] Pinus banksiana
[Termes IGN] Populus tremuloides
[Termes IGN] réflectance végétale
[Termes IGN] surveillance forestière
[Termes IGN] teneur en chlorophylle des feuillesRésumé : (auteur) Accurate modelling of leaf chlorophyll content over a range of spatial and temporal scales is central to monitoring vegetation stress and physiological condition, and vegetation response to different ecological, climatic and anthropogenic drivers. A process-based modelling approach can account for variation in other factors affecting canopy reflectance, providing a more accurate estimate of chlorophyll content across different vegetation species, time-frames, and broader spatial extents. However, physically-based modelling studies usually use hyperspectral data, neglecting a wealth of data from broadband and multispectral sources. In this study, we assessed the potential for using canopy (4-Scale) and leaf radiative transfer (PROSPECT4/5) models to estimate leaf chlorophyll content using canopy Landsat satellite data and simulated Landsat bands from leaf level hyperspectral reflectance data. Over 600 leaf samples were used to test the performance of PROSPECT for different vegetation species, including black spruce (Picea mariana), sugar maple (Acer saccharum), trembling aspen (Populus tremuloides) and jack pine (Pinus banksiana). At the leaf level, hyperspectral and simulated Landsat bands showed very similar results to laboratory measured chlorophyll (R2 = 0.77 and R2 = 0.75, respectively). Comparisons between PROSPECT4 modelled chlorophyll from simulated Landsat and hyperspectral spectra showed a very close correspondence (R2 = 0.97, root mean square error (RMSE) = 3.01 μg/cm2), as did simulated reflectance bands from other broadband and narrowband sensors (MODIS: R2 = 0.99, RMSE = 1.80 μg/cm2; MERIS: R2 = 0.97, RMSE = 2.50 μg/cm2 and SPOT5 HRG: R2 = 0.96, RMSE = 5.38 μg/cm2). Modelled leaf chlorophyll content from Landsat 5 TM canopy reflectance data, acquired from over 40 ground validation sites, demonstrated a strong relationship with measured leaf chlorophyll content (R2 = 0.78, RMSE = 8.73 μg/cm2, p Numéro de notice : A2015-691 Affiliation des auteurs : non IGN Thématique : FORET/IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.isprsjprs.2015.01.008 En ligne : https://doi.org/10.1016/j.isprsjprs.2015.01.008 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=78326
in ISPRS Journal of photogrammetry and remote sensing > vol 102 (April 2015) . - pp 85 - 95[article]Object-based assessment of burn severity in diseased forests using high-spatial and high-spectral resolution MASTER airborne imagery / Gang Chen in ISPRS Journal of photogrammetry and remote sensing, vol 102 (April 2015)
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Titre : Object-based assessment of burn severity in diseased forests using high-spatial and high-spectral resolution MASTER airborne imagery Type de document : Article/Communication Auteurs : Gang Chen, Auteur ; Margaret R. Metz, Auteur ; David M. Rizzo, Auteur ; et al., Auteur Année de publication : 2015 Article en page(s) : pp 38 - 47 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image optique
[Termes IGN] analyse d'image orientée objet
[Termes IGN] analyse en composantes principales
[Termes IGN] Californie (Etats-Unis)
[Termes IGN] délimitation
[Termes IGN] houppier
[Termes IGN] image à ultra haute résolution
[Termes IGN] image aérienne
[Termes IGN] image MASTER
[Termes IGN] impact sur l'environnement
[Termes IGN] incendie de forêt
[Termes IGN] maladie phytosanitaire
[Termes IGN] réflectance végétaleRésumé : (auteur) Forest ecosystems are subject to a variety of disturbances with increasing intensities and frequencies, which may permanently change the trajectories of forest recovery and disrupt the ecosystem services provided by trees. Fire and invasive species, especially exotic disease-causing pathogens and insects, are examples of disturbances that together could pose major threats to forest health. This study examines the impacts of fire and exotic disease (sudden oak death) on forests, with an emphasis on the assessment of post-fire burn severity in a forest where trees have experienced three stages of disease progression pre-fire: early-stage (trees retaining dried foliage and fine twigs), middle-stage (trees losing fine crown fuels), and late-stage (trees falling down). The research was conducted by applying Geographic Object-Based Image Analysis (GEOBIA) to MASTER airborne images that were acquired immediately following the fire for rapid assessment and contained both high-spatial (4 m) and high-spectral (50 bands) resolutions. Although GEOBIA has gradually become a standard tool for analyzing high-spatial resolution imagery, high-spectral resolution data (dozens to hundreds of bands) can dramatically reduce computation efficiency in the process of segmentation and object-based variable extraction, leading to complicated variable selection for succeeding modeling. Hence, we also assessed two widely used band reduction algorithms, PCA (principal component analysis) and MNF (minimum noise fraction), for the delineation of image objects and the subsequent performance of burn severity models using either PCA or MNF derived variables. To increase computation efficiency, only the top 5 PCA and MNF and top 10 PCA and MNF components were evaluated, which accounted for 10% and 20% of the total number of the original 50 spectral bands, respectively. Results show that if no band reduction was applied the models developed for the three stages of disease progression had relatively similar performance, where both spectral responses and texture contributed to burn assessments. However, the application of PCA and MNF introduced much greater variation among models across the three stages. For the early-stage disease progression, neither band reduction algorithms improved or retained the accuracy of burn severity modeling (except for the use of 10 MNF components). Compared to the no-band-reduction scenario, band reduction led to a greater level of overestimation of low-degree burns and underestimation of medium-degree burns, suggesting that the spectral variation removed by PCA and MNF was vital for distinguishing between the spectral reflectance from disease-induced dried crowns (still retaining high structural complexity) and fire ash. For the middle-stage, both algorithms improved the model R2 values by 2–37%, while the late-stage models had comparable or better performance to those using the original 50 spectral bands. This could be explained by the loss of tree crowns enabling better signal penetration, thus leading to reduced spectral variation from canopies. Hence, spectral bands containing a high degree of random noise were correctly removed by the band reduction algorithms. Compared to the middle-stage, the late-stage forest stands were covered by large piles of fallen trees and branches, resulting in higher variability of MASTER imagery. The ability of band reduction to improve the model performance for these late-stage forest stands was reduced, because the valuable spectral variation representing the actual late-stage forest status was partially removed by both algorithms as noise. Our results indicate that PCA and MNF are promising for balancing computation efficiency and the performance of burn severity models in forest stands subject to the middle and late stages of sudden oak death disease progression. Compared to PCA, MNF dramatically reduced image spectral variation, generating larger image objects with less complexity of object shapes. Whereas, PCA-based models delivered superior performance in most evaluated cases suggesting that some key spectral variability contributing to the accuracy of burn severity models in diseased forests may have been removed together with true spectral noise through MNF transformations. Numéro de notice : A2015-475 Affiliation des auteurs : non IGN Thématique : FORET Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.isprsjprs.2015.01.004 En ligne : https://doi.org/10.1016/j.isprsjprs.2015.01.004 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=77183
in ISPRS Journal of photogrammetry and remote sensing > vol 102 (April 2015) . - pp 38 - 47[article]A physics-based unmixing method to estimate subpixel temperatures on mixed pixels / Manuel Cubero-Castan in IEEE Transactions on geoscience and remote sensing, vol 53 n° 4 (April 2015)
PermalinkWuhan ionospheric oblique-incidence sounding system and its new application in localization of ionospheric irregularities / Shu-Zhu Shi in IEEE Transactions on geoscience and remote sensing, vol 53 n° 4 (April 2015)
PermalinkEstimating ionospheric delay using GPS/Galileo signals in the E5 band / Olivier Julien in Inside GNSS, vol 10 n° 2 (March - April 2015)
PermalinkEmploying ground and satellite-based QuickBird data and Random forest to discriminate five tree species in a Southern African Woodland / Samuel Adelabu in Geocarto international, vol 30 n° 3 - 4 (March - April 2015)
PermalinkÉtude comparée de quatre indicateurs qualifiant le champ visuel d’un piéton en milieu urbain / Thomas Leduc in Revue internationale de géomatique, vol 25 n° 1 (mars - mai 2015)
PermalinkLevelling co-located GNSS and tide gauge stations using GNSS reflectometry / Alvaro Santamaria Gomez in Journal of geodesy, vol 89 n° 3 (March 2015)
PermalinkA multidimensional extension of the concept of coherence in polarimetric SAR interferometry / Jose Luis Alvarez-Perez in IEEE Transactions on geoscience and remote sensing, vol 53 n° 3 (March 2015)
PermalinkPositioning in challenging environments using ultra-wideband sensor networks / Zoltan Koppanyi in GPS world, vol 26 n° 3 (March 2015)
PermalinkProgressive band processing of constrained energy minimization for subpixel detection / Chein-I Chang in IEEE Transactions on geoscience and remote sensing, vol 53 n° 3 (March 2015)
PermalinkSequential estimation of surface water mass changes from daily satellite gravimetry data / Guillaume L. Ramilien in Journal of geodesy, vol 89 n° 3 (March 2015)
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