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Affiner la recherche Interroger des sources externesPotential of Sentinel-1 data for monitoring temperate mixed forest phenology / Pierre-Louis Frison in Remote sensing, vol 10 n° 12 (December 2018)
Titre : Potential of Sentinel-1 data for monitoring temperate mixed forest phenology Type de document : Article/Communication Auteurs : Pierre-Louis Frison Année de publication : 2018 Projets : 3-projet - voir note / Article en page(s) : n° 2049 Note générale : bibliographie
This research was funding by the Centre National d’Etudes Spatiales (CNES), grant number DCT/SI/TR/2016-01532Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de télédétection
[Termes IGN] analyse diachronique
[Termes IGN] arbre caducifolié
[Termes IGN] coefficient de rétrodiffusion
[Termes IGN] cohérence des données
[Termes IGN] données polarimétriques
[Termes IGN] Fontainebleau, forêt de (Seine-et-Marne)
[Termes IGN] forêt tempérée
[Termes IGN] image radar moirée
[Termes IGN] image Sentinel-SAR
[Termes IGN] phénologie
[Termes IGN] signature spectrale
[Termes IGN] surveillance forestièreRésumé : (auteur) In this study, the potential of Sentinel-1 data to seasonally monitor temperate forests was investigated by analyzing radar signatures observed from plots in the Fontainebleau Forest of the Ile de France region, France, for the period extending from March 2015 to January 2016. Radar backscattering coefficients, σ0 and the amplitude of temporal interferometric coherence profiles in relation to environmental variables are shown, such as in situ precipitation and air temperature. The high temporal frequency of Sentinel-1 acquisitions (i.e., twelve days, or six, if both Sentinel-1A and B are combined over Europe) and the dual polarization configuration (VV and VH over most land surfaces) made a significant contribution. In particular, the radar backscattering coefficient ratio of VV to VH polarization, σ0VV/σ0VH , showed a well-pronounced seasonality that was correlated with vegetation phenology, as confirmed in comparison to NDVI profiles derived from Landsat-8 (r = 0.77) over stands of deciduous trees. These results illustrate the high potential of Sentinel-1 data for monitoring vegetation, and as these data are not sensitive to the atmosphere, the phenology could be estimated with more accuracy than optical data. These observations will be quantitatively analyzed with the use of electromagnetic models in the near future. Numéro de notice : A2018-669 Affiliation des auteurs : UPEM-LASTIG+Ext (2016-2019) Thématique : FORET/IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.3390/rs10122049 Date de publication en ligne : 17/12/2018 En ligne : https://doi.org/10.3390/rs10122049 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=94271
in Remote sensing > vol 10 n° 12 (December 2018) . - n° 2049[article]
Titre : Potential of Sentinel-1 data for vegetation monitoring Type de document : Article/Communication Auteurs : Pierre-Louis Frison 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 
Titre : F-ORE-T, l'Observatoire de Recherche en Environnement sur le fonctionnement des écosystèmes forestiers Titre original : F-ORE-T, the environmental research observatory on the functioning of forest ecosystems Type de document : Article/Communication Auteurs : Guy Landmann, Auteur ; Damien Maurice, Auteur ; André Granier, Auteur ; Serge Rambal, Auteur ; Jacques Ranger, Auteur ; Claude Nys, Auteur ; Laurent Saint André, Auteur ; Eric Dufrêne, Auteur ; Damien Bonal, Auteur ; Denis Loustau, Auteur ; Luc Croisé, Auteur Editeur : Versailles : Quae Année de publication : 2005 Conférence : EcoFor 2005, De l'observation des écosystèmes forestiers à l'information sur la forêt 22/02/2005 23/02/2005 Paris France open access proceedings Importance : pp 7 - 19 Note générale : Résumé en français et anglais. Bibliogr Langues : Français (fre) Descripteur : [Termes IGN] bilan du carbone
[Termes IGN] eau pluviale
[Termes IGN] écosystème forestier
[Termes IGN] recherche forestière
[Termes IGN] Réseau national de suivi à long terme des écosystèmes forestiers RENECOFOR
[Vedettes matières IGN] Ecologie forestièreRésumé : (Auteur) Depuis 2003, l'observatoire de recherche en environnement sur le fonctionnement des écosystèmes forestiers (F-ORE-T) rassemble les huit sites-ateliers français (gérés par l'INRA, le CNRS, et le CIRAD) consacrés à l'étude des cycles des éléments minéraux, du carbone et de l'eau et le réseau RENECOFOR (géré par l'ONF). Cet article présente succinctement l'observatoire, ses objectifs, les principes adoptés pour la collecte, la gestion et la mise à disposition des données, ainsi que l'activité scientifique à laquelle F-ORE-T sert de support. Numéro de notice : C2005-017 Affiliation des auteurs : non IGN Thématique : BIODIVERSITE/FORET Nature : Communication En ligne : http://www.symposcience.org/exl-doc/colloque/ART-00002045.pdf Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=66961 Documents numériques
en open access
F-ORE-TAdobe Acrobat PDF
Titre : Toward universal broad leaf chlorophyll indices using PROSPECT simulated database and hyperspectral reflectance measurements Type de document : Article/Communication Auteurs : G. Le Maire, Auteur ; C. François, Auteur ; Eric Dufrêne, Auteur Année de publication : 2004 Article en page(s) : pp 1 - 28 Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de télédétection
[Termes IGN] albedo
[Termes IGN] chlorophylle
[Termes IGN] erreur moyenne quadratique
[Termes IGN] feuillu
[Termes IGN] indice de végétation
[Termes IGN] réflectance végétale
[Termes IGN] réseau neuronal artificielRésumé : (Auteur) Fifty-three leaves were randomly sampled on different deciduous tree species, representing a wide range of chlorophyll contents, tree ages, and leaf structural features. Their reflectance was measured between 400 and 800 nm with a 1-nm step, and their chlorophyll content determined by extraction. A larger simulated database (11,583 spectra) was built using the PROSPECT model, in order to test, calibrate, and obtain universal indices, i.e., indices applicable to a wide range of species and leaf structure. To our knowledge, almost all leaf chlorophyll indices published in the literature since 1973 have been tested on both databases. Fourteen canonical types of indices (published ones and new ones) were identified, and their wavelengths calibrated on the simulated database as well as on the experimental database to determine the best wavelengths and, hence, the best performances in chlorophyll estimation for each index types. These indices go from simple reflectance ratios to more sophisticated indices using reflectance first derivatives (using the Savitzky and Golay method). We also tested other nondestructive methods to obtain total chlorophyll concentration: SPAD (Minolta Camera, Osaka, Japan) and neural networks. The validity of the actual PROSPECT model is challenged by our results: Important discordances are found when the indices are calculated with PROSPECT compared to experimental data, especially for some indices and wavelengths. The discordance is even greater when the indices are determined with PROSPECT and applied on the experimental database. A new calibration of PROSPECT is therefore necessary for any study aiming at using simulated spectra to determine or to calibrate indices. The "peak jump" and the multiplepeak feature observed on the first derivative of the reflectances (e.g., in the Red-Edge Inflection Point [REIP] index) has been investigated. It was shown that chlorophyll absorption alone can explain this feature. The peak jump disqualifies the REIP to be a valuable chlorophyll index. A simple modified difference ratio gave the best results among all published indices (cross-validated RMSE 2.1 [ug/cm2 on the experimental database). After calibration on the experimental database, modified Simple Ratio (mSR) and modified Nonnalized Difference (mND) indices gave the best performances (RMSECV = 1. 8 ug/cm2 on the experimental database). The new Double Difference (DD) index, although not the best on the experimental database (RMSECV = 2.9 [ug/cm2), has the best results on the larger simulated database (RMSE = 3.7 gg/cm2 ) and is expected to give good results on larger experimental databases. The best reflectance-based indices give better performances than the current commercial nondestructive device SPAD (RMSECV = 4.5 ug/cm2). In this leaf-level study, the best indices are very near from each other, so that complex methods are useless: REIP-like, neural networks, and derivative-based indices are not necessary and give worst results than simpler properly chosen indices. These conclusions will certainly be different for a canopy-level study, where the derivative-based indices may perform significantly better than the other ones. Numéro de notice : A2004-008 Affiliation des auteurs : non IGN Thématique : FORET/IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.rse.2003.09.004 En ligne : https://doi.org/10.1016/j.rse.2003.09.004 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=26536
in Remote sensing of environment > vol 89 n° 1 (15/01/2004) . - pp 1 - 28[article]
