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Investigation of Sentinel-1 time series for sensitivity to fern vegetation in an European temperate forest / Marlin Mueller (2021)  

Public Titre : Investigation of Sentinel-1 time series for sensitivity to fern vegetation in an European temperate forest Type de document : Article/Communication Auteurs : Marlin Mueller, Auteur ; Clémence Dubois, Auteur ; Thomas Jagdhuber, Auteur ; Carsten Pathe, Auteur ; Christiane Schmullius, Auteur Editeur : International Society for Photogrammetry and Remote Sensing ISPRS Année de publication : 2021 Collection : International Archives of Photogrammetry, Remote Sensing and Spatial Information Sciences, ISSN 1682-1750 num. 43-B2-2021 Conférence : ISPRS 2021, Commission 2, XXIV ISPRS Congress, Imaging today foreseeing tomorrow 05/07/2021 09/07/2021 Nice Virtuel France OA Archives Commission 2 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de télédétection [Termes IGN] Allemagne [Termes IGN] Filicophyta [Termes IGN] forêt tempérée [Termes IGN] image Sentinel-SAR [Termes IGN] phénologie [Termes IGN] série temporelle [Termes IGN] variation saisonnière Mots-clés libres : Pteridium aquilinum Résumé : (auteur) In this study, a dense Copernicus Sentinel-1 time series is analyzed to gain a better understanding of the influence of undergrowth vegetation, in particular of eagle fern (Pteridium aquilinum), on the C-band SAR signal in a temperate forest in the Free State of Thuringia, Germany. Even if signals from the ground below the canopy may not be expected at C-band, previous studies showed seasonal fluctuations of the backscatter for temperate forests without canopy closure, notably for evergreen coniferous stands. Many factors can be responsible for these observed fluctuations, but in this study, we analyze one possible factor: the presence of undergrowth vegetation, in particular, of fern. Especially, the Sentinel-1 backscatter signal is analyzed for different acquisition configurations regarding its temporal and its spatial stability at different growth stages. This time series study shows that a difference of backscattered signal of up to 0.7 dB exists between forest patches with a dense fern density in the understory and the ones with low undergrowth vegetation. This signal difference depends on the season and is remarkably strong comparing winter (no fern undergrowth) with summer (major fern undergrowth). Numéro de notice : C2021-018 Affiliation des auteurs : non IGN Thématique : FORET/IMAGERIE Nature : Communication DOI : 10.5194/isprs-archives-XLIII-B3-2021-127-2021 Date de publication en ligne : 28/06/2021 En ligne : https://doi.org/10.5194/isprs-archives-XLIII-B3-2021-127-2021 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=98070

Using ENVISAT ASAR global mode data for surface soil moisture retrieval over Oklahoma, USA / Carsten Pathe in IEEE Transactions on geoscience and remote sensing, vol 47 n° 2 (February 2009)  

Public [article]  inIEEE Transactions on geoscience and remote sensing > vol 47 n° 2 (February 2009) . - pp 468 - 480 Titre : Using ENVISAT ASAR global mode data for surface soil moisture retrieval over Oklahoma, USA Type de document : Article/Communication Auteurs : Carsten Pathe, Auteur ; W. Wagner, Auteur ; D. Sabel, Auteur ; et al., Auteur Année de publication : 2009 Article en page(s) : pp 468 - 480 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image [Termes IGN] analyse comparative [Termes IGN] bande C [Termes IGN] bruit (théorie du signal) [Termes IGN] diffusométrie [Termes IGN] filtrage du bruit [Termes IGN] humidité du sol [Termes IGN] image Envisat-ASAR [Termes IGN] image ERS-SAR [Termes IGN] Oklahoma (Etats-Unis) Résumé : (Auteur) The advanced synthetic aperture radar (ASAR) onboard of the satellite ENVISAT can be operated in global monitoring (GM) mode. ASAR GM mode has delivered the first global multiyear C-band backscatter data set in HH polarization at a spatial resolution of 1 km. This paper investigates if ASAR GM can be used for retrieving soil moisture using a change detection approach over large regions. A method previously developed for the European Remote Sensing (ERS) scatterometer is adapted for use with ASAR GM and tested over Oklahoma, USA. The ASAR-GM-derived relative soil moisture index is compared to 50-km ERS soil moisture data and pointlike in situ measurements from the Oklahoma MESONET. Even though the scale gap from ASAR GM to the in situ measurements is less pronounced than in the case of the ERS scatterometer, the correlation for ASAR against the in situ measurements is, in general, somewhat weaker than for the ERS scatterometer. The analysis suggests that this is mainly due to the much higher noise level of ASAR GM compared to the ERS scatterometer. Therefore, some spatial averaging to 3-10 km is recommended to reduce the noise of the ASAR GM soil moisture images. Nevertheless, the study demonstrates that ASAR GM allows resolving spatial details in the soil moisture patterns not observable in the ERS scatterometer measurements while still retaining the basic capability of the ERS scatterometer to capture temporal trends over large areas. Copyright IEEE Numéro de notice : A2009-148 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1109/TGRS.2008.2004711 En ligne : https://doi.org/10.1109/TGRS.2008.2004711 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=29778 [article]

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