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Auteur Bénédicte Fruneau
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First results of ground displacement monitoring in Paris (France) with Sentinel 1 A/B time series / Matthias Jauvin (2017)
Titre : First results of ground displacement monitoring in Paris (France) with Sentinel 1 A/B time series Type de document : Article/Communication Auteurs : Matthias Jauvin, Auteur ; Yajing Yan, Auteur ; Bénédicte Fruneau , Auteur ; Emmanuel Trouvé, Auteur ; Pierre Gusmano, Auteur Editeur : Paris : Agence Spatiale Européenne ASE / European Space Agency ESA Année de publication : 2017 Conférence : Fringe 2017, 10th International Workshop on Advances in the Science and Applications of SAR Interferometry and Sentinel-1 InSAR 05/06/2017 09/06/2017 Helsinki Finlande programme sans actes Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image radar et applications
[Termes IGN] image Sentinel-SAR
[Termes IGN] Paris (75)
[Termes IGN] surveillance géologiqueRésumé : (auteur) SAR differential interferometry represents an efficient tool to spatially monitor small ground deformations. During the last fifteen years, methods based on image time series, such as Persistent Scatterers technique, have shown their capabilities for monitoring finer displacements with millimeter precision. With the launch of Sentinel 1A and 1B in April 2014 and 2016, it is now possible to work with free time series of medium resolution images. The rapid revisit time (6 days) of this new constellation limits the temporal decorrelation, which makes it possible to have a high PS density, especially in urban areas. This reduction of the distance between PSs would then reduce the dispersion of the displacement measurements, so that the main source of error in deformation measurement will be due to the variation of the atmospheric composition.Major cities such as the city of Paris are experiencing constant changes that involve major construction works, both on the surface and underground. Paris for instance has started a new project called “Grand Paris”, which aims at transforming the Parisian metropolitan area with in particular major developments in transport network (subway, train and tramway). Such projects usually come with important pumping of groundwater or large excavations, whose surface impacts must be monitored with precision during and after the operations. In this context, Sentinel 1 data is a promising alternative of precedent radar satellite images, which guarantees the continuous availability of data for all applications and offers a good opportunity to develop operational monitoring applications. Even with a medium resolution, it is still possible to consider a use of this technique for monitoring displacements related to human activity (pumping of groundwater, construction of underground structures...) in urban areas. In this paper, we will present our first results obtained with a stack of Sentinel 1A and 1B images (29 images from S1-A and S1-B already processed, probably 45 for the Fringe workshop) acquired in IW mode. The PS processing is performed by using Gamma software. Some specific areas where construction works have already started are currently investigated to try to identify meaningful displacement patterns. In order to avoid limitations such as difficult PS identification and wrong interpretation of the deformation, we consider integrating PS results in processes of monitoring with others geodetic measurements (GPS, tachometry or leveling) acquired by companies specialized in high-precision topography, in order to better analyze and understand the deformations, their related processes and risks. Numéro de notice : C2017-055 Affiliation des auteurs : UPEM-LASTIG+Ext (2016-2019) Thématique : IMAGERIE Nature : Poster nature-HAL : Poster-avec-CL DOI : sans Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=96652 Potential of Sentinel-1 data for vegetation monitoring / Pierre-Louis Frison (2017)
Titre : Potential of Sentinel-1 data for vegetation monitoring Type de document : Article/Communication Auteurs : Pierre-Louis Frison , Auteur ; Bénédicte Fruneau , Auteur ; Kamel Soudani, Auteur ; Eric Dufrêne, Auteur ; Thuy Le Toan, Auteur ; Thierry Koleck, Auteur ; Jean-Français Dejoux, Auteur ; Ludovic Villard, Auteur ; Eric Mougin, Auteur Editeur : Valence [Espagne] : Universidad de Valencia Année de publication : 2017 Conférence : RAQRS 2017, 5th international symposium on Recent Advance in Quantitative Remote Sensing 18/09/2017 22/09/2017 Valence Espagne open access proceedings Langues : Anglais (eng) Résumé : (auteur) The monitoring of seasonal variations of Earth Surfaces needs acquisitions realized with high temporal frequencies. Radar remote sensing data have shown its potential for surface parameters monitoring (biomass and soil moisture). For example, the high temporal frequency of acquisitions (about 1-5 days depending of the latitude) realized par radar spaceborne scatterometers, such as those onboard ERS or METOP satellites allowed the quantitative estimation of yearly biomass and soil moisture estimations over semi-arid areas, such as the Sahelian region. The associated coarse spatial resolution (20 – 50 km) makes these data dedicated applications at regional and global scales. The Sentinel-1 mission allows to acquire of radar data every 12 days from the period extending from March 2015 to August 2016, when only Sentinel-1A operated alone. This period is reduced to 6 days since September 2016 by the combination of Sentinel-1B acquisitions. Consequently, it allows for the first time to assess the potential of radar data acquired with this revisiting time associated to a spatial resolution of about 20 m. In addition to the radar intensity, data acquired by the CSAR (C-band Synthetic Aperture Radar) onboard Sentinel-1 allow to access to he phase information. Consequently, interferometric products between two consecutive aquisitions can be generated, such as the interferometric coherence ρ. In this talk we analyze temporal profiles of radar backscattering coefficient σ0 as well as coherence |ρ| over vegetated areas. Two different sites are considered, both located in France: a temperate forest near Fontainebleau, in the region of Ile de France, and an agricultural area located near Toulouse. Primary results show that on the contrary to existing SAR missions, characterized by a temporal repetitivity of about one month, the 12 days temporal period, combined to the dual polarization (both VV and VH polarizations are acquired in the Interferometric Wide Swath mode over land surfaces) allow to observe a seasonal cycle in the σ0 temporal profile. This temporal behaviour, which appears to be time coincident with the leaves activity period over the Fontainebleau Forest, is particularly emphasis with the polarization ration, i.e.: σ0VV⁄σ0VH. The coherence behaviour appears to be low (≈ 0.2) and constant most of the year over the forest. It appears that the highest seasonal variations are observed over agricultural fields where both σ0 and |ρ| temporal profiles show complementary behaviour. Numéro de notice : C2017-050 Affiliation des auteurs : UPEM-LASTIG+Ext (2016-2019) Nature : Communication nature-HAL : ComSansActesPubliés-Unpublished DOI : sans Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=91948 Present-day deformation in Taiwan mountain belt as monitored by InSAR / Bénédicte Fruneau (2017)
Titre : Present-day deformation in Taiwan mountain belt as monitored by InSAR Type de document : Article/Communication Auteurs : Bénédicte Fruneau , Auteur ; Erwan Pathier, Auteur ; Marie-Pierre Doin, Auteur ; Jyr-Ching Hu, Auteur ; Hsin Tung, Auteur Editeur : Paris : Agence Spatiale Européenne ASE / European Space Agency ESA Année de publication : 2017 Conférence : Fringe 2017, 10th International Workshop on Advances in the Science and Applications of SAR Interferometry and Sentinel-1 InSAR 05/06/2017 09/06/2017 Helsinki Finlande programme sans actes Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image radar et applications
[Termes IGN] déformation de la croute terrestre
[Termes IGN] interféromètrie par radar à antenne synthétique
[Termes IGN] surveillance géologique
[Termes IGN] TaïwanRésumé : (auteur) Taiwan Island, resulting from oblique collision between Philippine sea plate and Eurasian plate converging at a rate of about 8 cm per year, is one of the most active tectonic region in the world. With a subtropical environment, it is faced to different hazards, including earthquakes, debris flow, landslides, and flooding. The precise measurement of the present-day ground displacements at the scale of the whole Taiwan Island is thus essential in several domains of Earth Sciences, in particular for earthquake cycle study and earthquake hazard assessment, for subsidence and landslide monitoring, and also to better understand the kinematics and mechanics of mountain building. In the framework of our complete mapping of Taiwan Island with InSAR, we use in this study the full archive of SAR data acquired by ALOS-1 satellite on the 2007-2011 period. ALOS L-band data are very effective in the vegetated and hilly Taiwan environment. SAR images are processed through a small baseline approach with NSBAS interferometric chain (Doin et al., 2015). It includes several corrections applied before unwrapping, in particular correction of atmospheric delays predicted from the global atmospheric re-analysis ERA-Interim model, and local DEM error correction. These corrections are of particular importance as they reduce the variance of the phase across regions with high topographic gradients, hence preventing unwrapping errors. Unwrapping process is also performed using a specific scheme, taking into account the information of colinearity. Thanks to this careful processing, we are able to unwrap across the Central Range, a challenging area with more than 3000m of topographic ranges. InSAR offers an unprecedented continuous view of deformation field of a large part of the Central Range. LOS velocity map obtained on track 446 shows a clear pattern of deformation, consistent with a rapid uplift of the Central Range South of the island. This uplift, already partially documented by GPS and leveling, is clearly mapped here and seems to show overall continuity. However, details of this map should be analyzed with caution.This is a real contribution of InSAR with respect to GPS, with a dramatic increase of the spatial information: even if the density of GPS stations is high in Taiwan, they are mostly distributed around the Central Range, and do not offer such spatial sampling.On this track, InSAR results allow also to connect spatially south western part of Taiwan, mapping the deformations of the Foothills and the Coastal Plain, and the southern end of the Longitudinal Valley, showing aseismic creep. Numéro de notice : C2017-054 Affiliation des auteurs : UPEM-LASTIG+Ext (2016-2019) Autre URL associée : vers HAL Thématique : IMAGERIE Nature : Poster nature-HAL : Poster-avec-CL DOI : sans Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=96651
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