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Building a small fire database for Sub-Saharan Africa from Sentinel-2 high-resolution images / Emilio Chuvieco in Science of the total environment, vol 845 (November 1 2022)  

Public [article]  inScience of the total environment > vol 845 (November 1 2022) . - n° 157139 Titre : Building a small fire database for Sub-Saharan Africa from Sentinel-2 high-resolution images Type de document : Article/Communication Auteurs : Emilio Chuvieco, Auteur ; Ekhi Roteta, Auteur ; Matteo Sali, Auteur ; et al., Auteur Année de publication : 2022 Article en page(s) : n° 157139 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Termes IGN] Afrique subsaharienne [Termes IGN] base de données localisées [Termes IGN] image Sentinel-MSI [Termes IGN] zone sinistrée Résumé : (auteur) Coarse resolution sensors are not very sensitive at detecting small fire patches, making current estimations of global burned areas (BA) very conservative. Using medium or high-resolution sensors to generate BA products becomes then a priority, particularly in areas where fires tend to be small and frequent. Building on previous work that developed a small fire dataset (SFD) for Sub-Saharan Africa for 2016, this paper presents a new version of the dataset for 2019 using the two Sentinel-2 satellites (A and B) and VIIRS active fires. Total estimated BA was 4.8 Mkm2. This value was much higher than estimations from two global, coarser-spatial resolution BA products based on MODIS data for the same area and period: 80 % greater than estimates from FireCCI51 (based on MODIS 250 m bands) and 120 % larger than MCD64A1 (based on MODIS 500 m bands). The main differences were observed in those months with higher fire occurrence (November to January for the Northern Hemisphere regions and June to September for the Southern Hemisphere ones). Accuracy assessment of the SFD product was based on a novel sampling strategy designed to obtain independent fire reference perimeters. Validation results showed remarkable high accuracy values comparing to existing global BA products. Overall omission errors (OE) were estimated as 8.5 %, commission errors (CE) as 15.0 %, with a Dice Coefficient of 87.7 %. All of these estimations implied significant improvements over the global, coarser spatial resolution BA products (OE > 50 % and CE > 20 % for the same area and period), as well as over the previous SFD product for 2016 of the same area, generated from a single Sentinel-2 satellite and MODIS active fires (OE = 26.5 % and CE = 19.3 %). Temporal accuracies greatly increased as well with the new product, with 92.5 % of fires detected within the first 10 days of occurrence. Numéro de notice : A2022-570 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article DOI : 10.1016/j.scitotenv.2022.157139 Date de publication en ligne : 13/07/2022 En ligne : https://doi.org/10.1016/j.scitotenv.2022.157139 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=101279 [article]

Laboratory measurements of plant drying: Implications to estimate moisture content from radiative transfer models in two temperate species / Sara Jurdao in Photogrammetric Engineering & Remote Sensing, PERS, vol 80 n° 5 (May 2014)  

Public [article]  inPhotogrammetric Engineering & Remote Sensing, PERS > vol 80 n° 5 (May 2014) . - pp 451 - 459 Titre : Laboratory measurements of plant drying: Implications to estimate moisture content from radiative transfer models in two temperate species Type de document : Article/Communication Auteurs : Sara Jurdao, Auteur ; Marta Yebra, Auteur ; Patricia Oliva, Auteur ; Emilio Chuvieco, Auteur Année de publication : 2014 Article en page(s) : pp 451 - 459 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de télédétection [Termes IGN] chlorophylle [Termes IGN] Fagus (genre) [Termes IGN] incendie de forêt [Termes IGN] indice d'humidité [Termes IGN] Leaf Area Index [Termes IGN] modèle de transfert radiatif [Termes IGN] Quercus pedunculata [Termes IGN] réflectance végétale [Termes IGN] risque majeur [Termes IGN] teneur en eau de la végétation Résumé : (Auteur) The estimation of live fuel moisture content (LFMC) is necessary for fire danger assessment. Several studies have successfully used satellite imagery to estimate LFMC, both using empirical and simulation approaches (Yebra et al., 2013). The latter are based on Radiative Transfer Models (BTM). They are generally more robust and easier to generalize, but they rely heavily on the proper parameterization. Since some of the input parameters are associated with different physiological processes, a better understanding of how those parameters co-vary is necessary for constraining the simulation scenarios, thus avoiding combinations of parameters that are unlikely to occur (for instance, in temperate ecosystems, it is unlikely to find simultaneously high values of leaf chlorophyll and low values of leaf moisture). To improve parameterization of RTM models for LFMC estimation, we conducted a laboratory experiment to measure trends in leaf and canopy variables of two tree species broadly distributed in Eurosiberian climates: Beech (Fagus sylvatica L.) and pedunculate Oak (Quercus robur L.). Measurements of LFMC, equivalent water thickness (EWT), dry matter content (DMC), chlorophyll (ClHh), leaf area index (LAl), leaf angle distribution (LIDF), crown height to width ratio (CHW) and plant reflectance were performed. Significant positive correlations were found between LFMC and EWT (Rs >0.5), and negative ones were found between both parameters and CMb (Rs Numéro de notice : A2014-242 Affiliation des auteurs : non IGN Thématique : FORET/IMAGERIE Nature : Article DOI : 10.14358/PERS.80.5.451 En ligne : https://doi.org/10.14358/PERS.80.5.451 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=33145 [article]