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Monitoring herbaceaous fuel moisture content with Spot-Vegetation times-series for fire risk prediction in savanna ecosystems / Jan Verbesselt in Remote sensing of environment, vol 108 n° 4 (29 June 2007)
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Titre : Monitoring herbaceaous fuel moisture content with Spot-Vegetation times-series for fire risk prediction in savanna ecosystems Type de document : Article/Communication Auteurs : Jan Verbesselt, Auteur ; B. Somers, Auteur ; et al., Auteur Année de publication : 2007 Article en page(s) : pp 357 - 368 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de télédétection
[Termes IGN] analyse diachronique
[Termes IGN] combustible
[Termes IGN] herbe
[Termes IGN] image SPOT-Végétation
[Termes IGN] indice de végétation
[Termes IGN] prévention des risques
[Termes IGN] risque naturel
[Termes IGN] savane
[Termes IGN] surveillance écologique
[Termes IGN] teneur en eau de la végétationRésumé : (Auteur) This paper evaluated the capacity of SPOT VEGETATION time-series to monitor herbaceous fuel moisture content (FMC) in order to improve fire risk assessment in the savanna ecosystem of Kruger National Park in South Africa. In situ herbaceous FMC data were used to assess the Normalized Difference Vegetation Index (NDVI), Normalized Difference Water Index (NDWI), Vegetation Dryness Index (VDI), Improved VDI (IVDI), and Accumulated Relative NDVI Decrement (ARND) during the dry season. The effect of increasing amounts of dead vegetation on the monitoring capacity of derived indices was studied by sampling mixed live and dead FMC. The IVDI was proposed as an improvement of the VDI to monitor herbaceous FMC during the dry season. The IVDI is derived by replacing NDVI with the integrated Relative Vegetation Index (iRVI), as an approximation of yearly herbaceous biomass, when analyzing the 2-dimensional space with NDWI. It was shown that the iRVI offered more information than the NDVI in combination with NDWI to monitor FMC. The VDI and IVDI exhibited a significant relation to FMC with R2 of 0.25 and 0.73, respectively. The NDWI, however, correlated best with FMC (R2 = 0.75), while the correlation of ARND and FMC was weaker (R2 = 0.60) than that found for NDVI, NDWI, and IVDI. The use of in situ herbaceous FMC consequently indicated that NDWI is appropriate as spatio-temporal information source of herbaceous FMC variation which can be used to optimize fire risk and behavior assessment for fire management in savanna ecosystems. Copyright Elsevier Numéro de notice : A2007-299 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.rse.2006.11.019 En ligne : https://doi.org/10.1016/j.rse.2006.11.019 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=28662
in Remote sensing of environment > vol 108 n° 4 (29 June 2007) . - pp 357 - 368[article]An empirical investigation of cross-sensor relationships of NDVI and red/near-infrared reflectance using EO-1 Hyperion data / T. Miura in Remote sensing of environment, vol 100 n° 2 (30 January 2006)
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Titre : An empirical investigation of cross-sensor relationships of NDVI and red/near-infrared reflectance using EO-1 Hyperion data Type de document : Article/Communication Auteurs : T. Miura, Auteur ; A. Huete, Auteur ; Hiroki Yoshioka, Auteur Année de publication : 2006 Article en page(s) : pp 223 - 236 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de télédétection
[Termes IGN] analyse comparative
[Termes IGN] bande rouge
[Termes IGN] Brésil
[Termes IGN] étalonnage des données
[Termes IGN] filtre passe-bande
[Termes IGN] flore locale
[Termes IGN] forêt tropicale
[Termes IGN] image EO1-Hyperion
[Termes IGN] image hyperspectrale
[Termes IGN] image Landsat-ETM+
[Termes IGN] image Terra-MODIS
[Termes IGN] Normalized Difference Vegetation Index
[Termes IGN] rayonnement proche infrarouge
[Termes IGN] réflectance spectrale
[Termes IGN] savaneRésumé : (Auteur) Long term observations of global vegetation from multiple satellites require much effort to ensure continuity and compatibility due to differences in sensor characteristics and product generation algorithms. In this study, we focused on the band-pass filter differences and empirically investigated cross-sensor relationships of the normalized difference vegetation index (NDVI) and reflectance. The specific objectives were: 1) to understand the systematic trends in cross-sensor relationships of the NDVI and reflectance as a function of spectral band-passes, 2) to examine/ identify the relative importance of the spectral features (i.e., the green peak, red edge, and leaf liquid water absorption regions) in and the mechanism(s) of causing the observed systematic trends, and 3) to evaluate the performance of several empirical cross-calibration methods in modelling the observed systematic trends. A Level 1A Hyperion hyperspectral image acquired over a tropical forest-savanna transitional region in Brazil was processed to simulate atmospherically corrected reflectances and NDVI for various band-passes, including Terra Moderate Resolution Imaging Spectro-radiometer (MODIS), NOAA-14 Advanced Very High Resolution Radiometer (AVHRR), and Landsat7 Enhanced Thematic Mapper Plus (ETM+). Data were extracted from various land cover types typically found in tropical forest and savanna biomes and used for analyses. Both NDVI and reflectance relationships among the sensors were neither linear nor unique and were found to exhibit complex patterns and band-pass dependencies. The reflectance relationships showed strong land cover dependencies. The NDVI relationships, in contrast, did not show land cover dependencies, but resulted in non-linear forms. From sensitivity analyses, the green peak (550 nm) and red-NIR transitional (680780 nm) features were identified as the key factors in producing the observed land cover dependencies and non-linearity in cross-sensor relationships. In particular, differences in the extents to which the red and/or NIR band-passes included these features significantly influenced the forms and degrees of non-linearity in the relationships. Translation of MODIS NDVI to "AVHRR Iike" NDVI using a weighted average of MODIS green and red bands performed very poorly, resulting in no reduction of overall discrepancy between MODIS and AVHRR NDVI. Cross-calibration of NDVI and reflectance using NDVI-based quadratic functions performed well, reducing their differences to +.025 units for the NDVI and +.01 units for the reflectances; however, many of the translation results suffered from bias errors. The present results suggest that distinct translation equations and coefficients need to be developed for every sensor pairs and that land cover-dependency need to be explicitly accounted for to reduce bias errors. Numéro de notice : A2006-034 Affiliation des auteurs : non IGN Thématique : FORET/IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.rse.2005.10.010 En ligne : https://doi.org/10.1016/j.rse.2005.10.010 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=27761
in Remote sensing of environment > vol 100 n° 2 (30 January 2006) . - pp 223 - 236[article]Two decades of normalized difference vegetation index changes in South America: identifying the imprint of global change / J.M. Paruelo in International Journal of Remote Sensing IJRS, vol 25 n° 14 (July 2004)
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Titre : Two decades of normalized difference vegetation index changes in South America: identifying the imprint of global change Type de document : Article/Communication Auteurs : J.M. Paruelo, Auteur ; M.F. Garbulsky, Auteur ; et al., Auteur Année de publication : 2004 Article en page(s) : pp 2793 - 2806 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de télédétection
[Termes IGN] Amérique du sud
[Termes IGN] analyse diachronique
[Termes IGN] atmosphère terrestre
[Termes IGN] biome
[Termes IGN] changement climatique
[Termes IGN] couvert végétal
[Termes IGN] forêt équatoriale
[Termes IGN] forêt tempérée
[Termes IGN] Normalized Difference Vegetation Index
[Termes IGN] photosynthèse
[Termes IGN] production primaire brute
[Termes IGN] savaneRésumé : (Auteur) Estimates of carbon uptake at the continental scale become urgently needed as the role of countries as net sinks or sources of carbon gains political and economic importance. Despite uncertainties related to radiation use efficiency, the amount of photosynthetically active radiation (PAR) intercepted by the canopy is a reliable estimator of primary production. Theoretical and empirical data support the relationship between the Normalized Difference Vegetation Index (NDVI) derived from the Advanced Very High Resolution Radiometer sensor on National Oceanic & Atmospheric Administration satellites and the fraction of PAR intercepted by green canopies. It is shown, for the period 1981-2000, that there is an overall increase in the radiation intercepted by the canopy over South America by 1.3%, with rainforests making the largest absolute contribution (45%), followed by savannas (23%). Under conditions of minimal agricultural use, disturbance and anthropogenic N deposition, humid temperate forests showed the highest proportional increase in NDVI during the last two decades (4.9%). Deserts showed a net reduction in NDVI relative to the 1981-1985 average (-4.4%). The expansion of agriculture over the last two decades was associated with NDVI reductions over subtropical forests. NDVI trends in South American region highlight a biome-dependent imprint of major global change noticeable in only two decades. Numéro de notice : A2004-292 Affiliation des auteurs : non IGN Thématique : FORET/IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1080/01431160310001619526 En ligne : https://doi.org/10.1080/01431160310001619526 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=26819
in International Journal of Remote Sensing IJRS > vol 25 n° 14 (July 2004) . - pp 2793 - 2806[article]Exemplaires(1)
Code-barres Cote Support Localisation Section Disponibilité 080-04121 RAB Revue Centre de documentation En réserve L003 Exclu du prêt Comparison of land surface emissivity and radiometric temperature derived from MODIS and ASTER sensors / F. Jacob in Remote sensing of environment, vol 90 n° 2 (30/03/2004)
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Titre : Comparison of land surface emissivity and radiometric temperature derived from MODIS and ASTER sensors Type de document : Article/Communication Auteurs : F. Jacob, Auteur ; F. Petitcolin, Auteur ; et al., Auteur Année de publication : 2004 Article en page(s) : pp 137 - 152 Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image
[Termes IGN] analyse comparative
[Termes IGN] correction atmosphérique
[Termes IGN] emissivité
[Termes IGN] image Terra-ASTER
[Termes IGN] image Terra-MODIS
[Termes IGN] savane
[Termes IGN] température au sol
[Termes IGN] transfert radiatif
[Termes IGN] zone semi-arideRésumé : (Auteur) This study compared surface emissivity and radiometric temperature retrievals derived from data collected with the MODerate resolution Imaging Spectroradionieter (MODIS) and Advanced Spacebome Thermal Emission Reflection Radiometer (ASTER) sensors, onboard the NASA's Earth Observation System (EOS)-TERRA satellite. Two study sites were selected: a semi-arid area located in northern Chilmalman desert, USA, and a Savannah landscape located in central Africa. Atmospheric corrections were performed using the MODTRAN 4 atmospheric radiative transfer code along with atmospheric profiles generated by the National Center for Environmental Predictions (NCEP). Atmospheric radiative properties were derived from MODTRAN 4 calculations according to the sensor swaths, which yielded different strategies from one sensor to the other. The MODIS estimates were then computed using a designed Temperature-Independent Spectral Indices of Emissivity (TISIE) method. The ASTER estimates were derived using the Temperature Emissivity Separation (TES) algorithm. The MODIS and ASTER radiometric temperature retrievals were in good agreement when the atmospheric corrections were similar, with differences lower than 0.9 K. The emissivity estimates were compared for MODIS/ASTER matching bands at 8.5 and 11um. It was shown that the retrievals agreed well, with RMSD ranging from 0.005 to 0.0 15, and biases ranging from - 0.0 1 to 0.005. At 8.5 um, the ranges of emissivities from both sensors were very similar. At 11 um, however, the ranges of MODIS values were broader than those of the ASTER estimates. The larger MODIS values were ascribed to the gray body problem of the TES algorithm, whereas the lower MODIS values were not consistent with field references. Finally, we assessed the combined effects of spatial variability and sensor resolution. It was shown that for the study areas we considered, these effects were not critical. Numéro de notice : A2004-140 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.rse.2003.11.015 En ligne : https://doi.org/10.1016/j.rse.2003.11.015 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=26667
in Remote sensing of environment > vol 90 n° 2 (30/03/2004) . - pp 137 - 152[article]Integrating imaging spectroscopy and neural networks to map grass quality in the Kruger National Park, South Africa / Onisimo Mutanga in Remote sensing of environment, vol 90 n° 1 (15/03/2004)
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Titre : Integrating imaging spectroscopy and neural networks to map grass quality in the Kruger National Park, South Africa Type de document : Article/Communication Auteurs : Onisimo Mutanga, Auteur ; Andrew K. Skidmore, Auteur Année de publication : 2004 Article en page(s) : pp 104 - 115 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de télédétection
[Termes IGN] Afrique du sud (état)
[Termes IGN] analyse comparative
[Termes IGN] azote
[Termes IGN] bande infrarouge
[Termes IGN] bande visible
[Termes IGN] erreur moyenne quadratique
[Termes IGN] herbe
[Termes IGN] image aérienne
[Termes IGN] image HYMAP
[Termes IGN] image hyperspectrale
[Termes IGN] régression linéaire
[Termes IGN] régression multiple
[Termes IGN] réseau neuronal artificiel
[Termes IGN] savaneRésumé : (Auteur) A new integrated approach, involving continuum-removed absorption features, the red edge position and neural networks, is developed and applied to map grass nitrogen concentration in an African savanna rangeland. Nitrogen, which largely determines the nutritional quality of grasslands, is commonly the most limiting nutrient for grazers. Therefore, the remote sensing of foliar nitrogen concentration in savanna rangelands is important for an improved understanding of the distribution and feeding patterns of wildlife. Continuum removal was applied on two absorption features located in the visible (R 550-757) and the SWIR (R 2015-2199) from an atmospherically corrected HYMAP MK1 image. A feature selection algorithm was used to select wavelength variables from the absorption features. Selected band depths from the absorption features as well as the red edge position (REP) were input into a backpropagation neural network. The best-trained neural network was used to map nitrogen concentration over the whole study area. Results indicate that the new integrated approach could explain 60% of the variation in savanna grass nitrogen concentration on an independent test data set, with a root mean square error (rmse) of 0. 13 (+ 8.3 0% of the mean observed nitrogen concentration). This result is better compared to the result obtained using multiple linear regression, which yielded an R of 38%, with a RMSE of 0.16 (+ 10.30% of the mean observed nitrogen concentration) on an independent test data set. The study demonstrates the potential of airborne hyperspectral data and neural networks to estimate and ultimately to map nitrogen concentration in the mixed species environments of Southern Africa. Numéro de notice : A2004-130 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.rse.2003.12.004 En ligne : https://doi.org/10.1016/j.rse.2003.12.004 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=26657
in Remote sensing of environment > vol 90 n° 1 (15/03/2004) . - pp 104 - 115[article]Dynamique de la déforestation et agriculture pionnière dans le sud-ouest de Madagascar : exploitation diachronique de l'imagerie satellitale haute résolution / F. Lasry in Photo interprétation, vol 40 n° 1 (Mars 2004)
PermalinkPredicting in situ pasture quality in the Kruger National Park, South Africa, using continuum-removed absorption features / Onisimo Mutanga in Remote sensing of environment, vol 89 n° 3 (15/02/2004)
PermalinkMapping potential risk of valley fever outbreaks in African savannas using vegetation index time series data / A. Anyamba in Photogrammetric Engineering & Remote Sensing, PERS, vol 68 n° 2 (February 2002)
PermalinkDetection of interannual vegetation responses to climatic variability using AVIRIS data in a coastal savanna in California / M. Garcia in IEEE Transactions on geoscience and remote sensing, vol 39 n° 7 (July 2001)
PermalinkRégionalisation du bilan hydrique à l'aide de mesures satellitaires pour l'étude du fonctionnement des écosystèmes de l'Afrique de l'ouest / O. Amram (1996)
PermalinkContribution des données NOAA-AVHRR à la caractérisation des savanes africaines / Valéry Gond (1995)
PermalinkPermalinkApport des données satellitaires en vue de l'estimation de la production primaire nette à l'échelle régionale / P. Loudjani (1993)
PermalinkAnalysis of vegetation seasonal evolution and mapping of forest cover in West Africa with the use of NOAA AVHRR HRPT data / Frédéric Achard in Photogrammetric Engineering & Remote Sensing, PERS, vol 56 n° 10 (october 1990)
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