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Titre : Observing mass transport to understand global change and to benefit society : Science and user needs - An international multi-disciplinary initiative for IUGG Type de document : Rapport Auteurs : Roland Pail, Éditeur scientifique ; Isabelle Panet , Auteur Editeur : Francfort sur le Main : Institut für Angewandte Geodäsie Année de publication : 2015 Collection : DGK - B, ISSN 0065-5317 num. 320 Importance : 124 p. Format : 21 x 30 cm ISBN/ISSN/EAN : 978-3-7696-8599-2 Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale
[Termes IGN] atmosphère terrestre
[Termes IGN] champ de pesanteur terrestre
[Termes IGN] changement climatique
[Termes IGN] cryosphère
[Termes IGN] données GOCE
[Termes IGN] données GRACE
[Termes IGN] gravimétrie spatiale
[Termes IGN] hydrosphère
[Termes IGN] série temporelleRésumé : (auteur) There is a strong science and user need for the sustained observation of the Earth's gravity field by means of dedicated satellite gravity missions. They provide a unique tool for observing changes and dynamic processes in the Earth system related to mass transport that is complementary to all other types of available and planned Earth observation missions. During the last decade, with satellite gravity missions of the first generation such as GRACE and GOCE, spectacular science results and new insights into the Earth's sub-systems hydrosphere, cryosphere, oceans, atmosphere and solid Earth, and their interaction, could be achieved. However, these results suffer from several shortfalls, such as limited temporal and spatial resolution and a limited length of the observation time series. The quantification of dynamic processes in the components of the Earth system and of their coupling provides an improved understanding of the global-state behavior of the Earth as well as direct and essential indicators of both subtle and dramatic global change. Therefore, a sustained observation of mass transport at fine scales for long periods is needed and mandatory for separating natural from human-made climate change effects. For the sustained observation of the global water cycle, satellite gravimetry is unique because it observes the completely integrated water column. It also enables the detection of sub-surface storage variations of groundwater or sub-glacial water mass exchanges that are generally difficult to access and that have specifically been hidden from remote sensing observations. Therefore, with satellite gravimetry all relevant processes of the global water cycle and mass changes of ice sheets and glaciers can be quantified, allowing to directly estimate their contribution to sea level rise. Because of its unique sensitivity to the solid Earth interior mass displacement, satellite gravity can also provide important information for monitoring the entire seismic cycle and understanding how stress accumulates and is released.
In spite of the great contributions by the first generation of satellite gravity missions, our current knowledge of mass transport and mass variations within the Earth system still has severe gaps. Due to a currently achievable resolution of 200-500 km (depending on signal strength, time scale and geographic location) on a monthly basis, worldwide only about 10% of the hydrological basins can be captured, and not even the largest individual outlet glacier drainage basins of ice sheets can be resolved. This limited spatial resolution also hampers the separation of different superimposed processes, thus leading to leakage problems and the misinterpretation of signals. […]Note de contenu : bibliographie Numéro de notice : 17566 Affiliation des auteurs : LASTIG LAREG+Ext (2012-mi2018) Autre URL associée : https://arts.units.it/retrieve/handle/11368/2849210/55596/DGK_Heft320_15.pdf Thématique : POSITIONNEMENT Nature : Rapport de recherche nature-HAL : RappRech DOI : sans En ligne : https://dgk.badw.de/fileadmin/user_upload/Files/DGK/docs/b-320.pdf Format de la ressource électronique : URL Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=91894 Documents numériques
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Observing mass transport to understand global change ... - pdf éditeurAdobe Acrobat PDF Reducing distance dependent bias in low-cost single frequency GPS network to complement dual frequency GPS stations in order to derive detailed surface deformation field / H.-Y. Chen in Survey review, vol 47 n° 340 (January 2015)
[article]
Titre : Reducing distance dependent bias in low-cost single frequency GPS network to complement dual frequency GPS stations in order to derive detailed surface deformation field Type de document : Article/Communication Auteurs : H.-Y. Chen, Auteur ; L. C. Kuo, Auteur ; J.-C. Lee, Auteur ; et al., Auteur Année de publication : 2015 Article en page(s) : pp 7 - 17 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale
[Termes IGN] correction atmosphérique
[Termes IGN] modèle ionosphérique
[Termes IGN] positionnement par GPS
[Termes IGN] récepteur monofréquence
[Termes IGN] réseau géodésique
[Termes IGN] station GPS
[Termes IGN] TaïwanRésumé : (auteur) A total of 17 low-cost single-frequency L1 global positioning system (GPS) receivers with real-time internet transmission have been set up to intensify the pre-existing network of continuously operating reference stations (CORS) in southeastern Taiwan since 2008. The main objective of this study is to investigate the validity and uncertainty of the L1 stations in southeastern Taiwan. It is well known that the main error source of single-frequency GPS relative positioning in low latitude areas comes from an atmospheric delay, even if the relative distance is only a few kilometres. In this study, two methods of correction algorithms, including adopting local ionospheric models and applying correction terms from local CORS, are tested to estimate the long-period accuracy of station positioning. Our results indicate that the standard deviation of calibrated relative positioning is in a linear trend with respect to the baseline length. The derived positioning accuracies from applying correction terms from CORS provide satisfactory results with the linear ratios of standard deviation/baseline of 0·11±0·02, 0·12±0·02, 0·44±0·06 mm km–1 in the north, east and up component, respectively for relative distances under 30 km. The corresponding positioning scatterings amount to 3, 3 and 13 mm, in the north, east and up component, respectively. Although the use of a local ionospheric model algorithm can significantly reduce positioning variation, especially in the north component, the use of the correction terms method yields the best positioning results for three components, horizontal and vertical. Numéro de notice : A2015-960 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.1179/1752270614Y.0000000095 En ligne : https://doi.org/10.1179/1752270614Y.0000000095 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=79947
in Survey review > vol 47 n° 340 (January 2015) . - pp 7 - 17[article]Seeing through shadow: Modelling surface irradiance for topographic correction of Landsat ETM+ data / Tobias Schulmann in ISPRS Journal of photogrammetry and remote sensing, vol 99 (January 2015)
[article]
Titre : Seeing through shadow: Modelling surface irradiance for topographic correction of Landsat ETM+ data Type de document : Article/Communication Auteurs : Tobias Schulmann, Auteur ; Marwan Katurji, Auteur ; Peyman Zawar-Reza, Auteur Année de publication : 2015 Article en page(s) : pp 14 - 24 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications photogrammétriques
[Termes IGN] aérosol
[Termes IGN] albedo
[Termes IGN] correction des ombres
[Termes IGN] montagne
[Termes IGN] Nouvelle-Zélande
[Termes IGN] pente
[Termes IGN] réflectance de surface
[Termes IGN] transfert radiatifRésumé : (Auteur) Despite advances in remote sensing, retrieving surface properties at high resolutions in complex terrain is a major challenge. Slope and aspect as well as the topography surrounding a target impact surface insolation and lead to variability in calculated surface reflectance even for homogeneous land cover. Retrieval of surface reflectance is particularly problematic in case of topographic shading, where the total irradiation at the surface is a combination of diffuse irradiation and terrain-reflected irradiation from nearby slopes. To facilitate the retrieval of surface reflectance from high-resolution optical remote sensing, we have explored the feasibility of using a three dimensional radiative transfer code to simulate gridded surface irradiance for a View the MathML source∼37km2 area in the New Zealand Southern Alps. We have tested the sensitivity of simulated irradiance and calculated surface reflectance both in- and outside shaded areas to atmospheric aerosol content, surface albedo, atmospheric boundary layer structure and different solar spectra. Retrieved surface reflectance has been shown to be highly sensitive to atmospheric aerosols and surface albedo, particularly for areas shaded by topography. Not considering atmospheric aerosols in topographic correction can increase derived surface reflectance by well over 50%, while terrain-reflected irradiance can contribute 40% to surface reflectance in shaded areas, even for wider valleys. Both factors should therefore be considered in topographic correction of satellite imagery, even for relatively aerosol-free atmospheres and low surface albedo. Topographic correction for the whole scene was performed with the model settings resulting in the smallest RMSD between surface reflectivity in shaded and unshaded areas of similar land cover. Topographic correction based on 3D radiative transfer simulations has proven to effectively remove topographic effects and almost equalise derived mean reflectance in- and outside shaded areas. While the effective removal of shadows likely requires a higher dynamic range than Landsat’s ETM+ can offer, we suggest further evaluation of this approach in future studies at other sites and with other sensors. Numéro de notice : A2014-634 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.isprsjprs.2014.10.004 En ligne : https://doi.org/10.1016/j.isprsjprs.2014.10.004 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=75060
in ISPRS Journal of photogrammetry and remote sensing > vol 99 (January 2015) . - pp 14 - 24[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 081-2015011 RAB Revue Centre de documentation En réserve L003 Disponible Validity and behaviour of tropospheric gradients estimated by GPS in Corsica / Laurent Morel in Advances in space research, vol 55 n° 1 ([01/01/2015])
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Titre : Validity and behaviour of tropospheric gradients estimated by GPS in Corsica Type de document : Article/Communication Auteurs : Laurent Morel, Auteur ; Eric Pottiaux, Auteur ; Frédéric Durand, Auteur ; et al., Auteur Année de publication : 2015 Article en page(s) : pp 135 - 149 Langues : Anglais (eng) Descripteur : [Termes IGN] Corse
[Termes IGN] GAMIT
[Termes IGN] GIPSY-OASIS
[Termes IGN] gradient de troposphère
[Termes IGN] retard troposphérique
[Vedettes matières IGN] Traitement de données GNSSRésumé : (auteur) Estimation of tropospheric gradients in GNSS data processing is a well-known technique to improve positioning (e.g. Bar-Sever et al., 1998; Chen and Herring, 1997). More recently, several authors also focused on the estimation of such parameters for meteorological studies and demonstrated their potential benefits (e.g. Champollion et al., 2004). Today, they are routinely estimated by several global and regional GNSS analysis centres but they are still not yet used for operational meteorology.
This paper discusses the physical meaning of tropospheric gradients estimated from GPS observations recorded in 2011 by 13 permanent stations located in Corsica Island (a French Island in the western part of Italy). Corsica Island is a particularly interesting location for such study as it presents a significant environmental contrast between the continent and the sea, as well as a steep topography.
Therefore, we estimated Zenith Total Delay (ZTD) and tropospheric gradients using two software: GAMIT/GLOBK (GAMIT version 10.5) and GIPSY-OASIS II version 6.1. Our results are then compared to radiosonde observations and to the IGS final troposphere products. For all stations we found a good agreement between the ZWD estimated by the two software (the mean of the ZWD differences is 1 mm with a standard deviation of 6 mm) but the tropospheric gradients are in less good agreement (the mean of the gradient differences is 0.1 mm with a standard deviation of 0.7 mm), despite the differences in the processing strategy (double-differences for GAMIT/GLOBK versus zero-difference for GIPSY-OASIS).
We also observe that gradient amplitudes are correlated with the seasonal behaviour of the humidity. Like ZWD estimates, they are larger in summer than in winter. Their directions are stable over the time but not correlated with the IWV anomaly observed by ERA-Interim. Tropospheric gradients observed at many sites always point to inland throughout the year. These preferred directions are almost opposite to the largest slope of the local topography as derived from the world Digital Elevation Model ASTER GDEM v2. These first results give a physical meaning to gradients but the origin of such directions need further investigations.Numéro de notice : A2015-297 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.asr.2014.10.004 En ligne : https://doi.org/10.1016/j.asr.2014.10.004 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=76458
in Advances in space research > vol 55 n° 1 [01/01/2015] . - pp 135 - 149[article]Using DORIS measurements for modeling the vertical total electron content of the Earth’s ionosphere / Denise Dettmering in Journal of geodesy, vol 88 n° 12 (December 2014)
[article]
Titre : Using DORIS measurements for modeling the vertical total electron content of the Earth’s ionosphere Type de document : Article/Communication Auteurs : Denise Dettmering, Auteur ; Marco Limberger, Auteur ; M. Schmidt, Auteur Année de publication : 2014 Article en page(s) : pp 1131 - 1143 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale
[Termes IGN] données DORIS
[Termes IGN] électron
[Termes IGN] ionosphère
[Termes IGN] teneur totale en électronsRésumé : (Auteur) The Doppler orbitography and radiopositioning integrated by satellite (DORIS) system was originally developed for precise orbit determination of low Earth orbiting (LEO) satellites. Beyond that, it is highly qualified for modeling the distribution of electrons within the Earth’s ionosphere. It measures with two frequencies in L-band with a relative frequency ratio close to 5. Since the terrestrial ground beacons are distributed quite homogeneously and several LEOs are equipped with modern receivers, a good applicability for global vertical total electron content (VTEC) modeling can be expected. This paper investigates the capability of DORIS dual-frequency phase observations for deriving VTEC and the contribution of these data to global VTEC modeling. The DORIS preprocessing is performed similar to commonly used global navigation satellite systems (GNSS) preprocessing. However, the absolute DORIS VTEC level is taken from global ionospheric maps (GIM) provided by the International GNSS Service (IGS) as the DORIS data contain no absolute information. DORIS-derived VTEC values show good consistency with IGS GIMs with a RMS between 2 and 3 total electron content units (TECU) depending on solar activity which can be reduced to less than 2 TECU when using only observations with elevation angles higher than 50∘ . The combination of DORIS VTEC with data from other space-geodetic measurement techniques improves the accuracy of global VTEC models significantly. If DORIS VTEC data is used to update IGS GIMs, an improvement of up to 12% can be achieved. The accuracy directly beneath the DORIS satellites’ ground-tracks ranges between 1.5 and 3.5 TECU assuming a precision of 2.5 TECU for altimeter-derived VTEC values which have been used for validation purposes. Numéro de notice : A2014-568 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-014-0748-2 Date de publication en ligne : 26/07/2014 En ligne : https://doi.org/10.1007/s00190-014-0748-2 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=74755
in Journal of geodesy > vol 88 n° 12 (December 2014) . - pp 1131 - 1143[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 266-2014121 SL Revue Centre de documentation Revues en salle Disponible Plume tracking with a mobile sensor based on incomplete and imprecise information / Juliane Brink in Transactions in GIS, vol 18 n° 5 (October 2014)PermalinkVoxel-optimized regional water vapor tomography and comparison with radiosonde and numerical weather model / Biyan Chen in Journal of geodesy, vol 88 n° 7 (July 2014)PermalinkA high-quality, homogenized, global, long-term (1993–2008) DORIS precipitable water data set for climate monitoring and model verification / Olivier Bock in Journal of geophysical research : Atmospheres, vol 119 n° 12 (2014)PermalinkLes effets de l'oscillation Nord-Atlantique sur les transferts de masse, vus par géodésie / Pierre Valty in XYZ, n° 139 (juin - août 2014)PermalinkApplication of SWACI products as ionospheric correction for single-point positioning: a comparative study / David Minkwitz in Journal of geodesy, vol 88 n° 5 (May 2014)PermalinkComparisons of atmospheric mass variations derived from ECMWF reanalysis and operational fields, over 2003–2011 / E. Forootan in Journal of geodesy, vol 88 n° 5 (May 2014)PermalinkDynamic modeling of GNSS troposphere wet delay for estimation of precipitable water vapour / Ahmed El-Mowafy in Journal of applied geodesy, vol 8 n° 1 (April 2014)PermalinkHyperspectral-based adaptive matched filter detector error as a function of atmospheric water vapor estimation / Allan W. Yarbrough in IEEE Transactions on geoscience and remote sensing, vol 52 n° 4 (April 2014)PermalinkAn improved dark object method to retrieve 500 m-resolution AOT (Aerosol Optical Thickness) image from MODIS data: A case study in the Pearl River Delta area, China / Lili Li in ISPRS Journal of photogrammetry and remote sensing, vol 89 (March 2014)PermalinkClimatological study of ionospheric irregularities over the European mid-latitude sector with GPS / Gilles Wautelet in Journal of geodesy, vol 88 n° 3 (March 2014)PermalinkImproved one/multi-parameter models that consider seasonal and geographic variations for estimating weighted mean temperature in ground-based GPS meteorology / Yi Bin Yao in Journal of geodesy, vol 88 n° 3 (March 2014)PermalinkWater vapor probabilistic retrieval using GNSS signals / Andrea Antonini in IEEE Transactions on geoscience and remote sensing, vol 52 n° 3 (March 2014)PermalinkGNSS ambiguity resolution with controllable failure rate for long baseline network RTK / Bofeng Li in Journal of geodesy, vol 88 n° 2 (February 2014)PermalinkIonospheric modeling using GPS: Greater fidelity using a 3D approach / Wei Zhang in GPS world, vol 25 n° 2 (February 2014)PermalinkModeling and sensing the vertical structure of the atmospheric path delay by microwave radiometry to correct SAR interferograms / Patrizia Basili in IEEE Transactions on geoscience and remote sensing, vol 52 n° 2 (February 2014)PermalinkStatistical data fusion of multi-sensor AOD over the Continental United States / Sweta Jinnagara Puttaswamy in Geocarto international, vol 29 n° 1 - 2 (February - April 2014)PermalinkAtmospheric water vapour sensing by means of differential absorption spectrometry using solar and lunar radiation / Stefan Walter Münch (2014)PermalinkDORIS tropospheric estimation at IGN : Current strategies, GPS intercomparisons and perspectives / Pascal Willis (2014)PermalinkPermalinkModélisation de la propagation troposphérique des signaux de positionnement par satellites : un tour d'horizon / Camille Desjardins (2014)Permalink