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Automatic detection of inland water bodies along altimetry tracks for estimating surface water storage variations in the Congo basin / Frédéric Frappart in Remote sensing, vol 13 n° 19 (October-1 2021)  

Public [article]  inRemote sensing > vol 13 n° 19 (October-1 2021) . - n° 3804 Titre : Automatic detection of inland water bodies along altimetry tracks for estimating surface water storage variations in the Congo basin Type de document : Article/Communication Auteurs : Frédéric Frappart, Auteur ; Pierre Zeiger, Auteur ; Julie Betbeder, Auteur ; Valéry Gond, Auteur ; Régis Bellot , Auteur ; Nicolas Baghdadi, Auteur ; Fabien Blarel, Auteur ; José Darrozes, Auteur ; Luc Bourrel, Auteur ; Frédérique Seyler, Auteur Année de publication : 2021 Projets : TOSCA / Article en page(s) : n° 3804 Note générale : bibliographie This research was funded by CNES TOSCA grants number CASCHMIR and SWHYM. Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image radar et applications [Termes IGN] classification par nuées dynamiques [Termes IGN] Congo (bassin) [Termes IGN] détection automatique [Termes IGN] données altimétriques [Termes IGN] eau de surface [Termes IGN] estimation statistique [Termes IGN] image Envisat-ASAR [Termes IGN] image Jason-AMR [Termes IGN] niveau de l'eau [Termes IGN] série temporelle [Termes IGN] stockage [Termes IGN] volume d'eau [Termes IGN] zone humide Résumé : (auteur) Surface water storage in floodplains and wetlands is poorly known from regional to global scales, in spite of its importance in the hydrological and the carbon balances, as the wet areas are an important water compartment which delays water transfer, modifies the sediment transport through sedimentation and erosion processes, and are a source for greenhouse gases. Remote sensing is a powerful tool for monitoring temporal variations in both the extent, level, and volume, of water using the synergy between satellite images and radar altimetry. Estimating water levels over flooded area using radar altimetry observation is difficult. In this study, an unsupervised classification approach is applied on the radar altimetry backscattering coefficients to discriminate between flooded and non-flooded areas in the Cuvette Centrale of Congo. Good detection of water (open water, permanent and seasonal inundation) is above 0.9 using radar altimetry backscattering from ENVISAT and Jason-2. Based on these results, the time series of water levels were automatically produced. They exhibit temporal variations in good agreement with the hydrological regime of the Cuvette Centrale. Comparisons against a manually generated time series of water levels from the same missions at the same locations show a very good agreement between the two processes (i.e., RMSE ≤ 0.25 m in more than 80%/90% of the cases and R ≥ 0.95 in more than 95%/75% of the cases for ENVISAT and Jason-2, respectively). The use of the time series of water levels over rivers and wetlands improves the spatial pattern of the annual amplitude of water storage in the Cuvette Centrale. It also leads to a decrease by a factor of four for the surface water estimates in this area, compared with a case where only time series over rivers are considered. Numéro de notice : A2021-935 Affiliation des auteurs : IGN+Ext (2020- ) Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.3390/rs13193804 Date de publication en ligne : 23/09/2021 En ligne : https://doi.org/10.3390/rs13193804 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=99542 [article]

Joint inversion of ground gravity data and satellite gravity gradients between Nepal and Bhutan: New insights on structural and seismic segmentation of the Himalayan arc / Rodolphe Cattin in Physics and chemistry of the Earth (A/B/C), vol 123 (October 2021)  

Public [article]  inPhysics and chemistry of the Earth (A/B/C) > vol 123 (October 2021) . - n° 103002 Titre : Joint inversion of ground gravity data and satellite gravity gradients between Nepal and Bhutan: New insights on structural and seismic segmentation of the Himalayan arc Type de document : Article/Communication Auteurs : Rodolphe Cattin, Auteur ; Théo Berthet, Auteur ; György Hetényi, Auteur ; Anita Thea Saraswati, Auteur ; Isabelle Panet , Auteur ; Stéphane Mazzotti, Auteur ; Cécilia Cadio, Auteur ; Matthieu Ferry, Auteur Année de publication : 2021 Projets : TOPO-Extreme / Cattin, Rodolphe, TOSCA / Cattin, Rodolphe Article en page(s) : n° 103002 Note générale : bibliographie This work was supported by grants from the Agence Nationale de la Recherche ANR-18-CE01-0017 and CNES TOSCA, as well as the Swiss National Science Foundation grant PP00P2_157627 (project OROG3NY). Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale [Termes IGN] Bhoutan [Termes IGN] gradient de gravitation [Termes IGN] gravimétrie spatiale [Termes IGN] Himalaya [Termes IGN] levé gravimétrique [Termes IGN] Népal [Termes IGN] séisme Résumé : (auteur) Along-strike variation in the geometry of lithospheric structures is a key control parameter for the occurrence and propagation of major interplate earthquakes in subduction and collision zones. The lateral segmentation of the Himalayan arc is now well-established from various observations, including topography, gravity anomalies, exhumation rates, and present-day seismic activity. Good knowledge of the main geometric features of these segments and their boundaries is thus the next step to improve seismic hazard assessment in this area. Following recent studies, we focus our approach on the transition zone between Nepal and Bhutan where both M > 8 earthquakes and changes in the geometry of the Indian plate have been documented. Ground gravity data sets are combined with satellite gravity gradients provided by the GOCE mission (Gravity Field and Steady-State Ocean Circulation Explorer) in a joint inversion to assess the location and the geometry of this transition. We obtain a ca. 10 km wide transition zone located at the western border of Bhutan that is aligned with the Madhupur fault in the foreland and coincides with the Dhubri–Chungthang fault zone and the Yadong-Gulu rift in Himalaya and southern Tibet, respectively. This sharp segment boundary at depth can act as a barrier to earthquake rupture propagation. It can possibly restrict the size of large earthquakes and thus reduce the occurrence probability of M > 9 earthquakes along the Main Himalayan Thrust. Numéro de notice : A2021-500 Affiliation des auteurs : UMR IPGP-Géod+Ext (2020- ) Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.pce.2021.103002 En ligne : https://doi.org/10.1016/j.pce.2021.103002 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=98261 [article]

Fast unsupervised multi-scale characterization of urban landscapes based on Earth observation data / Claire Teillet in Remote sensing, vol 13 n° 12 (June-2 2021)  

Public [article]  inRemote sensing > vol 13 n° 12 (June-2 2021) . - n° 2398 Titre : Fast unsupervised multi-scale characterization of urban landscapes based on Earth observation data Type de document : Article/Communication Auteurs : Claire Teillet, Auteur ; Benjamin Pillot, Auteur ; Thibault Catry, Auteur ; Laurent Demagistri, Auteur ; Dominique Lyszczarz, Auteur ; Marc Lang, Auteur ; Pierre Couteron, Auteur ; Nicolas Barbier, Auteur ; Arsène Adou Kouassi, Auteur ; Quentin Gunther , Auteur ; Nadine Dessay, Auteur Année de publication : 2021 Projets : GeoSud / Cattin, Rodolphe, TOSCA / Cattin, Rodolphe Article en page(s) : n° 2398 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de télédétection [Termes IGN] Bouaké [Termes IGN] Brasilia [Termes IGN] caractérisation [Termes IGN] empreinte [Termes IGN] image Pléiades-HR [Termes IGN] image Sentinel-MSI [Termes IGN] paysage urbain [Termes IGN] texture d'image [Termes IGN] zone urbaine Résumé : (auteur) Most remote sensing studies of urban areas focus on a single scale, using supervised methodologies and very few analyses focus on the “neighborhood” scale. The lack of multi-scale analysis, together with the scarcity of training and validation datasets in many countries lead us to propose a single fast unsupervised method for the characterization of urban areas. With the FOTOTEX algorithm, this paper introduces a texture-based method to characterize urban areas at three nested scales: macro-scale (urban footprint), meso-scale (“neighbourhoods”) and micro-scale (objects). FOTOTEX combines a Fast Fourier Transform and a Principal Component Analysis to convert texture into frequency signal. Several parameters were tested over Sentinel-2 and Pleiades imagery on Bouake and Brasilia. Results showed that a single Sentinel-2 image better assesses the urban footprint than the global products. Pleiades images allowed discriminating neighbourhoods and urban objects using texture, which is correlated with metrics such as building density, built-up and vegetation proportions. The best configurations for each scale of analysis were determined and recommendations provided to users. The open FOTOTEX algorithm demonstrated a strong potential to characterize the three nested scales of urban areas, especially when training and validation data are scarce, and computing resources limited. Numéro de notice : A2021-505 Affiliation des auteurs : ENSG+Ext (2020- ) Autre URL associée : vers HAL Thématique : IMAGERIE/INFORMATIQUE/URBANISME Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.3390/rs13122398 Date de publication en ligne : 19/06/2021 En ligne : https://doi.org/10.3390/rs13122398 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=98125 [article]

Past and present ITRF solutions from geophysical perspectives / Laurent Métivier in Advances in space research, vol 65 n° 12 (15 June 2020)  

Public [article]  inAdvances in space research > vol 65 n° 12 (15 June 2020) . - pp 2711 - 2722 Titre : Past and present ITRF solutions from geophysical perspectives Type de document : Article/Communication Auteurs : Laurent Métivier , Auteur ; Zuheir Altamimi , Auteur ; Hélène Rouby , Auteur Année de publication : 2020 Projets : TOSCA / Cattin, Rodolphe Article en page(s) : pp 2711 - 2722 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale [Termes IGN] champ de vitesse [Termes IGN] fonte des glaces [Termes IGN] International Terrestrial Reference Frame [Termes IGN] positionnement par GNSS [Termes IGN] rebond post-glaciaire [Termes IGN] vitesse Résumé : (auteur) Questions about the accuracy of the origin of the different versions of International Terrestrial Reference Frame (ITRF), have been regularly raised. In particular the origin drift between ITRF2000 and ITRF2005 (and subsequent ITRF solutions) is well-known to be problematic. Here, we look forward a sort of geophysical evaluation of ITRF solutions. We investigate GNSS vertical velocities provided by the last four ITRF solutions (ITRF2000 to ITRF2014; Altamimi et al., 2005, 2007, 2011, 2016) that we compare with different Global Isostatic Adjustment (GIA) model predictions. We find that each new ITRF solution appears to be more and more consistent with all GIA predictions, except ITRF2014 whose consistency with the GIA models depends on the date of observation. Indeed, GNSS observations and GIA predictions appear consistent at global scale at a level of ~4 mm/yr using ITRF2000 data, ~2.5–3 mm/yr using ITRF2005 data, and ~2 mm/yr using ITRF2008 data (global weighted root mean squares). For ITRF2014, the consistency between GNSS observations and GIA predictions is extremely high in 2000 (~1.5 mm/yr) but seems then to decrease with time (~2 mm/yr in 2013). This discrepancy is due to the recent ice melting effect that is not accounted for in GIA models, but clearly evidenced by ITRF2014 vertical velocities during the last years of observations, in particular in Greenland. Numéro de notice : A2020-364 Affiliation des auteurs : UMR IPGP-Géod (2020- ) Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.asr.2020.03.031 Date de publication en ligne : 06/04/2020 En ligne : https://doi.org/10.1016/j.asr.2020.03.031 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=96828 [article]

Joint inversion of GPS and high-resolution GRACE gravity data for the 2012 Wharton basin earthquakes / Michel Diament in Journal of geodynamics, vol 136 (May 2020)  

Public [article]  inJournal of geodynamics > vol 136 (May 2020) . - n° 101722 Titre : Joint inversion of GPS and high-resolution GRACE gravity data for the 2012 Wharton basin earthquakes Type de document : Article/Communication Auteurs : Michel Diament , Auteur ; Valentin O. Mikhailov, Auteur ; Elena P. Timoshkina, Auteur Année de publication : 2020 Projets : TOSCA / Cattin, Rodolphe Article en page(s) : n° 101722 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale [Termes IGN] coordonnées GPS [Termes IGN] déformation de la croute terrestre [Termes IGN] données GRACE [Termes IGN] élasticité [Termes IGN] Indien (océan) [Termes IGN] séisme [Termes IGN] viscosité Résumé : (auteur) The Wharton basin is situated in the north-eastern part of the Indian Ocean. In 2012 it hosted the largest intraplate strike-slip earthquakes ever recorded by geophysical networks. The Mw 8.6 earthquake of April 11, 2012, was preceded by a major foreshock (Mw 7.2) on January 10 and was followed two hours afterward by a Mw 8.2 event. These three large events occurred at the diffuse boundary between the Indian and Australian plates and were almost pure strike-slips on sub-vertical rupture surfaces. Using GRACE data, we first extracted the coseismic and postseismic gravity signals caused by these earthquakes. Then we fitted both GPS and the highest available spatial resolution of GRACE data using the geometry of the fault system suggested by Hill et al. (2015). We propose a regularization, which allows to solve for a linear problem in order to invert GPS and GRACE data under constraints on the rake angle. Our inversion yields a uniform displacement field on all elements of a given fault plane. Our solution shows that even the main displacement occurred on WNW trending faults, comparable displacement also occurred on a rupture striking NNE. Hence, we show that the deformation in this diffuse plate boundary region in 2012 was accommodated by displacements along both fault-systems. A viscoelastic relaxation of the asthenosphere with a Maxwell viscosity 1019 Pa∙s successfully explains the postseismic displacements at GPS sites and postseismic gravity signals. The limited postseismic aftershock activity suggests small postseismic slip in the area of the 2012 Wharton earthquakes contrary to what is often observed after large subduction event. Because a part of the observed signal could be related to afterslip, our obtained Maxwell viscosity value should be considered as a lower limit of the asthenospheric viscosity below the Wharton basin. Numéro de notice : A2020-876 Affiliation des auteurs : UMR IPGP-Géod+Ext (2020- ) Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.jog.2020.101722 Date de publication en ligne : 20/03/2020 En ligne : https://doi.org/10.1016/j.jog.2020.101722 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=99670 [article]

A warning against over-interpretation of seasonal signals measured by the Global Navigation Satellite System / Kristel Chanard in Nature communications, vol 11 (2020)  

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Vertical land motion in the Southwest and Central Pacific from available GNSS solutions and implications for relative sea levels / Valérie Ballu in Geophysical journal international, vol 218 n° 3 (September 2019)  

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Sensitivity of GPS tropospheric estimates to mesoscale convective systems in West Africa / Samuel Nahmani in Atmospheric chemistry and physics, vol 19 n° 14 (July 2019)  

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An analysis of gravitational gradients in rotated frames and their relation to oriented mass sources / Isabelle Panet in Journal of geophysical research : Solid Earth, vol 123 n° 12 (December 2018)  

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3D reconstruction from multi-view VHR-satellite images in MicMac / Ewelina Rupnik in ISPRS Journal of photogrammetry and remote sensing, vol 139 (May 2018)  

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Cartographie des déformations de surface sur l’île de Taiwan par interférométrie RADAR Sentinel-1 / Miloud Fekaouni (2018)

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Shallow geological structures triggered during the Mw 6.4 Meinong earthquake, southwestern Taiwan / Maryline Le Béon in Terrestrial Atmospheric Oceanic sciences journal, vol 28 n° 5 (October 2017)  

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Inverting Glacial Isostatic Adjustment signal using Bayesian framework and two linearly relaxing rheologies / Lambert Caron in Geophysical journal international, vol 209 n° 2 (May 2017)  

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Refined satellite image orientation in the free open-source photogrammetric tools Apero/MicMac / Ewelina Rupnik in ISPRS Annals of the Photogrammetry, Remote Sensing and Spatial Information Sciences, III-1 (July 2016)    

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Joint analysis of GOCE gravity gradients data of gravitational potential and of gravity with seismological and geodynamic observations to infer mantle properties / Marianne Greff-Lefftz in Geophysical journal international, vol 205 n° 1 (April 2016)  

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