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Universidad de Valencia
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Titre : Potential of Sentinel-1 data for vegetation monitoring Type de document : Article/Communication Auteurs : Pierre-Louis Frison , Auteur ; Bénédicte Fruneau
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
