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The open data HELI-DEM DTM for the western alpine area: computation and publication / L. Biagi in Applied geomatics, vol 8 n° 3-4 (December 2016)
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Titre : The open data HELI-DEM DTM for the western alpine area: computation and publication Type de document : Article/Communication Auteurs : L. Biagi, Auteur ; S. Caldera, Auteur ; L. Carcano, Auteur ; Marco Negretti, Auteur Année de publication : 2016 Article en page(s) : pp 191 - 200 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications photogrammétriques
[Termes IGN] Alpes
[Termes IGN] données altimétriques
[Termes IGN] données lidar
[Termes IGN] données localisées 3D
[Termes IGN] European Terrestrial Reference Frame
[Termes IGN] fusion de données
[Termes IGN] Italie
[Termes IGN] modèle numérique de surface
[Termes IGN] Suisse
[Termes IGN] transformation rapide de FourierRésumé : (Auteur) Two problems can arise in analyzing Digital Elevation Models (DEMs). Firstly, one interest region could be patched by several partly overlapping models that present similar accuracies and spatial resolutions; they should be merged in one unified model. Moreover, even when the interest region is completely covered by one model, local data with better accuracy could cover partial areas and should be properly merged. All these problems have been addressed within Helvetia-Italy Digital Elevation Model, a project funded by the European Regional Development Fund (ERDF). One specific aim of the project was the creation and the publication of a unified DEM for a part of the Alps between Italy and Switzerland. The interest area is prevalently mountainous, with elevations that range from about 200 to 4600 m. Various elevation datasets were available that were gridded with different spatial resolutions, in different reference frames and coordinates. Moreover, one high resolution LiDAR model was available for some areas. Firstly, a validation was performed that allowed the identification of few blunders and confirmed the general accuracy of the input data. Two DEMs have been produced. Both of them cover the whole project area (boundaries λ = 7.80° East and λ = 10.70° East, φ = 45.10° North and φ = 46.70° North) and are gridded in ETRF2000 geographical coordinates, with a spatial resolution of 2 × 10−4 degrees. The former (named HD-1) has been obtained by interpolating and merging all the low resolution models on a new common grid. HD-1 has been locally corrected by the LiDAR model, where it was available; to avoid sharp discontinuities, the corrections have been filtered by Fast Fourier Transform before applying them. The resulting model has been called HD-2. HD-1 and HD-2 are published by an open access geoservice. Numéro de notice : A2016--054 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article DOI : 10.1007/s12518-016-0176-5 Date de publication en ligne : 26/10/2016 En ligne : http://dx.doi.org/10.1007/s12518-016-0176-5 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=84201
in Applied geomatics > vol 8 n° 3-4 (December 2016) . - pp 191 - 200[article]An approach for estimating time-variable rates from geodetic time series / Olga Didova in Journal of geodesy, vol 90 n° 11 (November 2016)
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Titre : An approach for estimating time-variable rates from geodetic time series Type de document : Article/Communication Auteurs : Olga Didova, Auteur ; Brian Gunter, Auteur ; Riccardo Riva, Auteur ; et al., Auteur Année de publication : 2016 Article en page(s) : pp 1207 - 1221 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale
[Termes IGN] Antarctique
[Termes IGN] calotte glaciaire
[Termes IGN] compensation par moindres carrés
[Termes IGN] données GRACE
[Termes IGN] filtre de Kalman
[Termes IGN] Global Ocean Observing System
[Termes IGN] montée du niveau de la mer
[Termes IGN] niveau moyen des mers
[Termes IGN] optimisation (mathématiques)
[Termes IGN] positionnement par GPS
[Termes IGN] série temporelleRésumé : (Auteur) There has been considerable research in the literature focused on computing and forecasting sea-level changes in terms of constant trends or rates. The Antarctic ice sheet is one of the main contributors to sea-level change with highly uncertain rates of glacial thinning and accumulation. Geodetic observing systems such as the Gravity Recovery and Climate Experiment (GRACE) and the Global Positioning System (GPS) are routinely used to estimate these trends. In an effort to improve the accuracy and reliability of these trends, this study investigates a technique that allows the estimated rates, along with co-estimated seasonal components, to vary in time. For this, state space models are defined and then solved by a Kalman filter (KF). The reliable estimation of noise parameters is one of the main problems encountered when using a KF approach, which is solved by numerically optimizing likelihood. Since the optimization problem is non-convex, it is challenging to find an optimal solution. To address this issue, we limited the parameter search space using classical least-squares adjustment (LSA). In this context, we also tested the usage of inequality constraints by directly verifying whether they are supported by the data. The suggested technique for time-series analysis is expanded to classify and handle time-correlated observational noise within the state space framework. The performance of the method is demonstrated using GRACE and GPS data at the CAS1 station located in East Antarctica and compared to commonly used LSA. The results suggest that the outlined technique allows for more reliable trend estimates, as well as for more physically valuable interpretations, while validating independent observing systems. Numéro de notice : A2016-798 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-016-0918-5 En ligne : http://dx.doi.org/ 10.1007/s00190-016-0918-5 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=82575
in Journal of geodesy > vol 90 n° 11 (November 2016) . - pp 1207 - 1221[article]Evidence for postglacial signatures in gravity gradients: A clue in lower mantle viscosity / Laurent Métivier in Earth and planetary science letters, vol 452 (October 2016)
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Titre : Evidence for postglacial signatures in gravity gradients: A clue in lower mantle viscosity Type de document : Article/Communication Auteurs : Laurent Métivier , Auteur ; Lambert Caron, Auteur ; Marianne Greff-Lefftz, Auteur ; Gwendoline Pajot-Métivier
, Auteur ; Luce Fleitout, Auteur ; Hélène Rouby
, Auteur
Année de publication : 2016 Article en page(s) : pp 146 - 156 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique
[Termes IGN] Amérique du nord
[Termes IGN] anomalie de pesanteur
[Termes IGN] déformation de la croute terrestre
[Termes IGN] gradient de gravitation
[Termes IGN] manteau terrestre
[Termes IGN] paléocontinent
[Termes IGN] viscositéRésumé : (auteur) The Earth's surface was depressed under the weight of ice during the last glaciations. Glacial Isostatic Adjustment (GIA) induces the slow recession of the trough that is left after deglaciation and is responsible for a contemporary uplift rate of more than 1 cm/yr around Hudson Bay. The present-day residual depression, an indicator of still-ongoing GIA, is difficult to identify in the observed topography, which is predominantly sensitive to crustal heterogeneities. According to the most widespread GIA models, which feature a viscosity of 2–3×1021 Pa s2–3×1021 Pa s on top of the lower mantle, the trough is approximately 100 m deep and cannot explain the observed gravity anomalies across North America. These large anomalies are therefore usually attributed to subcontinental density heterogeneities in the tectosphere or to slab downwelling in the deep mantle.
Here, we use observed gravity gradients (GG) to show that the uncompensated GIA trough is four times larger than expected and that it is the main source of the North American static gravity signal. We search for the contribution to these GGs from mantle mass anomalies, which are deduced from seismic tomography and are mechanically coupled to the global mantle flow. This contribution is found to be small over Laurentia, and at least 82% of the GGs are caused by GIA. Such a contribution from GIA in these GG observations implies a viscosity that is greater than 1022 Pa s1022 Pa s in the lower mantle.
Our conclusions are a plea for GIA models with a highly viscous lower mantle, which confirm inferences from mantle dynamic models. Any change in GIA modelling has important paleoclimatological and environmental implications, encouraging scientists to re-evaluate the past ice history at a global scale. These implications, in turn, affect the contribution of bedrock uplift to the contemporaneous mass balance over Antarctica and Greenland and thus the present-day ice-melting rate as deduced from the GRACE space mission. Additionally, studies of the thermo-chemical structure of the lithosphere/crust under North America that exploit gravity or geodetic data should be corrected for a GIA model, which is not the case today.Numéro de notice : A2016-906 Affiliation des auteurs : LASTIG LAREG+Ext (2012-mi2018) Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.epsl.2016.07.034 Date de publication en ligne : 16/08/2016 En ligne : http://dx.doi.org/10.1016/j.epsl.2016.07.034 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=83034
in Earth and planetary science letters > vol 452 (October 2016) . - pp 146 - 156[article]Effects of forest structure and airborne laser scanning point cloud density on 3D delineation of individual tree crowns / Kaja Kandare in European journal of remote sensing, vol 49 n° 1 (2016)
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Titre : Effects of forest structure and airborne laser scanning point cloud density on 3D delineation of individual tree crowns Type de document : Article/Communication Auteurs : Kaja Kandare, Auteur ; Hans Ole Ørka, Auteur ; Jonathan Cheung-Wai Chan, Auteur ; Michele Dalponte, Auteur Année de publication : 2016 Article en page(s) : pp 337 - 359 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Lasergrammétrie
[Termes IGN] Alpes
[Termes IGN] délimitation
[Termes IGN] densité des points
[Termes IGN] données lidar
[Termes IGN] données localisées 3D
[Termes IGN] forêt alpestre
[Termes IGN] houppier
[Termes IGN] Italie
[Termes IGN] semis de points
[Termes IGN] structure d'un peuplement forestierRésumé : (auteur) This paper presents a 3D delineation method for airborne laser scanning point cloud. The method is based on an unsupervised clustering technique applied on horizontal slices followed by vertical merging based on overlapping among clusters. On an Alpine forest dataset, we analysed the effects of different forest structures and point cloud densities on tree crown delineation. Forest structure affects mainly the omission error, which eases with homogeneous tree spacing and sizes, while on the commission error forest structure has only slight effect. Delineation accuracy increases with higher point densities where Mann-Whitney-Wilcoxon test shows that accuracy differences between thinned data and original data are statistically significant. Numéro de notice : A2016-829 Affiliation des auteurs : non IGN Thématique : FORET/IMAGERIE Nature : Article DOI : 10.5721/EuJRS20164919 En ligne : http://dx.doi.org/10.5721/EuJRS20164919 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=82709
in European journal of remote sensing > vol 49 n° 1 (2016) . - pp 337 - 359[article]Using a regional numerical weather prediction model for GNSS positioning over Brazil / Daniele Barroca Marra Alves in GPS solutions, vol 20 n° 4 (October 2016)
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Titre : Using a regional numerical weather prediction model for GNSS positioning over Brazil Type de document : Article/Communication Auteurs : Daniele Barroca Marra Alves, Auteur ; Luiz Fernando Sapucci, Auteur ; Haroldo Antonio Marques, Auteur ; et al., Auteur Année de publication : 2016 Article en page(s) : pp 677 - 685 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale
[Termes IGN] Amazonie
[Termes IGN] Brésil
[Termes IGN] modèle de simulation
[Termes IGN] modèle météorologique
[Termes IGN] positionnement ponctuel précis
[Termes IGN] propagation troposphérique
[Termes IGN] station GNSS
[Termes IGN] teneur en vapeur d'eau
[Termes IGN] troposphèreRésumé : (Auteur) The global navigation satellite system (GNSS) can provide centimeter positioning accuracy at low costs. However, in order to obtain the desired high accuracy, it is necessary to use high-quality atmospheric models. We focus on the troposphere, which is an important topic of research in Brazil where the tropospheric characteristics are unique, both spatially and temporally. There are dry regions, which lie mainly in the central part of the country. However, the most interesting area for the investigation of tropospheric models is the wet region which is located in the Amazon forest. This region substantially affects the variability of humidity over other regions of Brazil. It provides a large quantity of water vapor through the humidity convergence zone, especially for the southeast region. The interconnection and large fluxes of water vapor can generate serious deficiencies in tropospheric modeling. The CPTEC/INPE (Center for Weather Forecasting and Climate Studies/Brazilian Institute for Space Research) has been providing since July 2012 a numerical weather prediction (NWP) model for South America, known as Eta. It has yield excellent results in weather prediction but has not been used in GNSS positioning. This NWP model was evaluated in precise point positioning (PPP) and network-based positioning. Concerning PPP, the best positioning results were obtained for the station SAGA, located in Amazon region. Using the NWP model, the 3D RMS are less than 10 cm for all 24 h of data, whereas the values reach approximately 60 cm for the Hopfield model. For network-based positioning, the best results were obtained mainly when the tropospheric characteristics are critical, in which case an improvement of up to 7.2 % was obtained in 3D RMS using NWP models. Numéro de notice : A2016--028 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.1007/s10291-015-0477-x En ligne : http://dx.doi.org/10.1007/s10291-015-0477-x Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=83930
in GPS solutions > vol 20 n° 4 (October 2016) . - pp 677 - 685[article]Floristic composition and across-track reflectance gradient in Landsat images over Amazonian forests / Javier Muro in ISPRS Journal of photogrammetry and remote sensing, vol 119 (September 2016)
PermalinkMethodology and software solutions for multicriteria evaluation of floodplain retention suitability / Rico Vogel in Cartography and Geographic Information Science, Vol 43 n° 4 (September 2016)
PermalinkBimodal pattern of seismicity detected at the ocean margin of an Antarctic ice shelf / Denis Lombardi in Geophysical journal international, vol 206 n° 2 (August 2016)
PermalinkDiagnostic study of a high‐precipitation event in the Western Mediterranean: adequacy of current operational networks / Samiro Khodayar in Quarterly Journal of the Royal Meteorological Society, vol 142 n° S1 (August 2016)
PermalinkA high-quality reprocessed ground-based GPS dataset for atmospheric process studies, radiosonde and model evaluation, and reanalysis of HyMeX Special Observing Period / Olivier Bock in Quarterly Journal of the Royal Meteorological Society, vol 142 n° S1 (August 2016)
PermalinkA multi-instrument and multi-model assessment of atmospheric moisture variability over the Western Mediterranean during HyMeX / Patrick Chazette in Quarterly Journal of the Royal Meteorological Society, vol 142 n° S1 (August 2016)
PermalinkA seamless weather–climate multi‐model intercomparison on the representation of a high impact weather event in the western Mediterranean: HyMeX IOP12 / Samiro Khodayar in Quarterly Journal of the Royal Meteorological Society, vol 142 n° S1 (August 2016)
PermalinkFast computation of general forward gravitation problems / Fabien Casenave in Journal of geodesy, vol 90 n° 7 (July 2016)
PermalinkMapping and characterization of hydrological dynamics in coastal marsh using high temporal resolution Sentinel-1 images / Cécile Cazals in Remote sensing, vol 8 n° 7 (July 2016)
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PermalinkSpatio-temporal change detection from multidimensional arrays: Detecting deforestation from MODIS time series / Meng Lu in ISPRS Journal of photogrammetry and remote sensing, vol 117 (July 2016)
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