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Assessing the effects of human-induced land degradation in the former homelands of northern South Africa with a 1 km AVHRR NDVI time-series / K.J. Wessels in Remote sensing of environment, vol 91 n° 1 (15/05/2004)
[article]
Titre : Assessing the effects of human-induced land degradation in the former homelands of northern South Africa with a 1 km AVHRR NDVI time-series Type de document : Article/Communication Auteurs : K.J. Wessels, Auteur ; S.D. Prince, Auteur ; et al., Auteur Année de publication : 2004 Article en page(s) : pp 47 - 67 Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de télédétection
[Termes IGN] Afrique du sud (état)
[Termes IGN] analyse comparative
[Termes IGN] dégradation de l'environnement
[Termes IGN] érosion hydrique
[Termes IGN] image Landsat-TM
[Termes IGN] image NOAA-AVHRR
[Termes IGN] Normalized Difference Vegetation Index
[Termes IGN] précipitation
[Termes IGN] production agricole
[Termes IGN] série temporelle
[Termes IGN] surface cultivéeRésumé : (Auteur) There is a pressing need for an objective, repeatable, systematic and spatially explicit measure of land degradation. In northeastern South Africa (SA), there are large areas of the former homelands that are widely regarded as degraded. A time-series of seasonally integrated 1 km, Advanced Very High Resolution Radiometer (AVHRR) normalized difference vegetation index (NDVI) data was used to compare degraded rangelands [mapped by the National Land Cover (NLC) using Landsat Thematic Mapper (TM) imagery] to nondegraded rangelands within the same land capability units (LCUs). Nondegraded and degraded areas in the same LCU (paired areas) were compared by: (i) testing for differerences in spatial mean NDVI values, (ii) calculating the relative degradation impact (RDI) as the difference between the spatial mean NDVI values of paired areas expressed as a percentage of nondegraded mean value, (iii) investigating the relationship between RDI and rainfall and (iv) comparing the resilience and stability of paired areas in response to natural variations in rainfall. The NDVI of degraded areas was significantly lower for most of the LCUs. Relative degradation impacts (RDI) across all LCUs ranged from 1% to 20% with an average of 9%. Although NDVI was related to rainfall, RDI was not. Degraded areas were no less stable or resilient than nondegraded. However, the productivity of degraded areas, i.e., the forage production per unit rainfall, was consistently lower than nondegraded areas, even within years of above normal rainfall. The results indicate that there has not been a catastrophic reduction in ecosystem function within degraded areas. Instead, degradation impacts were reflected as reductions in productivity that varied along a continuum from slight to severe, depending on the specific LCU. Numéro de notice : A2004-236 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.rse.2004.02.005 En ligne : https://doi.org/10.1016/j.rse.2004.02.005 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=26763
in Remote sensing of environment > vol 91 n° 1 (15/05/2004) . - pp 47 - 67[article]Artificial neural network-based techniques for the retrieval of SWE [snow water equivalent] and snow depth from SSM/I data / Marco Tedesco in Remote sensing of environment, vol 90 n° 1 (15/03/2004)
[article]
Titre : Artificial neural network-based techniques for the retrieval of SWE [snow water equivalent] and snow depth from SSM/I data Type de document : Article/Communication Auteurs : Marco Tedesco, Auteur ; J.T. Pulliainen, Auteur ; M. Takala, Auteur ; M.T. Hallikainen, Auteur ; P. Pampaloni, Auteur Année de publication : 2004 Article en page(s) : pp 76 - 85 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image
[Termes IGN] analyse comparative
[Termes IGN] Finlande
[Termes IGN] neige
[Termes IGN] réalité de terrain
[Termes IGN] réseau neuronal artificiel
[Termes IGN] Special sensor microwave imager
[Termes IGN] télédétection en hyperfréquenceRésumé : (Auteur) The retrieval of snow water equivalent (SWE) and snow depth is performed by inverting Special Sensor Microwave Imager (SSM/I) brightness temperatures at 19 and 37 GHz using artificial neural network ANN-based techniques. The SSM/I used data, which consist of Pathfinder Daily EASE-Grid brightness temperatures, were supplied by the National Snow and Ice Data Centre (NSIDC). They were gathered during the period of time included between the beginning of 1996 and the end of 1999 all over Finland. A ground snow data set based on observations of the Finnish Environment Institute (SYKE) and the Finnish Meteorological Institute (FMI) was used to estimate the performances of the technique. The ANN results were confronted with those obtained using the spectral polarization difference (SPD) algorithm, the HUT model-based iterative inversion and the Chang algorithm, by comparing the RMSE, the R , and the regression coefficients. In general, it was observed that the results obtained through ANN-based technique are better than, or comparable to, those obtained through other approaches, when trained with simulated data. Performances were very good when the ANN were trained with experimental data. Numéro de notice : A2004-129 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.rse.2003.12.002 En ligne : https://doi.org/10.1016/j.rse.2003.12.002 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=26656
in Remote sensing of environment > vol 90 n° 1 (15/03/2004) . - pp 76 - 85[article]Estimating fractional snow cover from MODIS using the normalized difference snow index / V.V. Salomonson in Remote sensing of environment, vol 89 n° 3 (15/02/2004)
[article]
Titre : Estimating fractional snow cover from MODIS using the normalized difference snow index Type de document : Article/Communication Auteurs : V.V. Salomonson, Auteur ; I. Appel, Auteur Année de publication : 2004 Article en page(s) : pp 351 - 360 Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de télédétection
[Termes IGN] bande infrarouge
[Termes IGN] bande visible
[Termes IGN] image Terra-MODIS
[Termes IGN] manteau neigeux
[Termes IGN] méthode robuste
[Termes IGN] neige
[Termes IGN] Normalized Difference Snow Index
[Termes IGN] réalité de terrainRésumé : (Auteur) Snow-cover information is important for a wide variety of scientific studies, water supply and management applications. The NASA Earth Observing System (EOS) Moderate Resolution Imaging Spectroradiometer (MODIS) provides improved capabilities to observe snow cover orn space and has been successfully using a normalized difference snow index (NDSI), along with threshold tests, to provide global, automated binary maps of snow cover. The NDSI is a spectral band ratio that takes advantage of the spectral differences of snow in short-wave infrared and visible MODIS spectral bands to identify snow versus other features in a scene. This study has evaluated whether there is a "signal" in the NDSI that could be used to estimate the fraction of snow within a 500 in MODIS pixel and thereby enhance the use of the NDSI approach in monitoring snow cover. Using Landsat 30-m observations as "ground truth," the percentage of snow cover was calculated for 500-m cells. Then a regression relationship between 500-m NDSI observations and fractional snow cover was developed over three different snow-covered regions and tested over other areas. The overall results indicate that the relationship between fractional snow cover and NDSI is reasonably robust when applied locally and over large areas like North America. The relationship offers advantages relative to other published fractional snow cover algorithms developed for global-scale use with MODIS. This study indicates that the fraction of snow cover within a MODIS pixel using this approach can be provided with a mean absolute error less than 0.1 over the range from 0.0 to 1.0 in fractional snow cover. Numéro de notice : A2004-019 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.rse.2003.10.016 En ligne : https://doi.org/10.1016/j.rse.2003.10.016 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=26547
in Remote sensing of environment > vol 89 n° 3 (15/02/2004) . - pp 351 - 360[article]Looking after water in Africa / J. Achache in ESA bulletin, n° 117 (February 2004)
[article]
Titre : Looking after water in Africa Type de document : Article/Communication Auteurs : J. Achache, Auteur ; J. Aschbacher, Auteur ; S. Briggs, Auteur Année de publication : 2004 Article en page(s) : pp 29 - 35 Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Acquisition d'image(s) et de donnée(s)
[Termes IGN] Afrique (géographie politique)
[Termes IGN] développement durable
[Termes IGN] eau souterraine
[Termes IGN] hydrogéologie
[Termes IGN] image satellite
[Termes IGN] précipitation
[Termes IGN] ressources en eauRésumé : (Auteur) Water resources, the “blue gold” of the 21st century, can be successfuly minitored from space using Earth-observation technology. Satellite can measure precipitation, atmospheric water content, soil moisture, surface run-off, lake and river levels, groundwater reservoirs, as well as ice and snow cover. Improved sensors, better modelling and a deeper understanding of the underlying science have substantially advanced our knowledge of the global water cycle in recent years. However, there are still major shortcomings in both the understanding and the observation of key parameters. The estimation of groundwater resources, for example, poses a major challenge, as they are not directly visible from space. Indirect methods based on gravity-field measurements, interferometery and altimetric monitoring of rivers need to be applied to gain knowledge of reservoir volumes and flows. In order to improve our capabilities and to offert this technology to people in developing countries, ESA has launched a new programme focusing on the use of space technology for water-resource management in Africa. The initiative, called 'TIGER' is a direct followup engagement of ESA's strong engagement in the 2002 Johannesburg World Summit off Sustainable Development, and implements its recommendations through concrete actions. Numéro de notice : A2004-156 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article DOI : sans Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=26683
in ESA bulletin > n° 117 (February 2004) . - pp 29 - 35[article]Narrowband-to-broadband albedo conversion for glacier ice and snow: equations based on modeling and ranges of validity of the equations / W. Greuell in Remote sensing of environment, vol 89 n° 1 (15/01/2004)
[article]
Titre : Narrowband-to-broadband albedo conversion for glacier ice and snow: equations based on modeling and ranges of validity of the equations Type de document : Article/Communication Auteurs : W. Greuell, Auteur ; J. Oerlemans, Auteur Année de publication : 2004 Article en page(s) : pp 95 - 105 Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de télédétection
[Termes IGN] albedo
[Termes IGN] éclairement énergétique
[Termes IGN] erreur moyenne quadratique
[Termes IGN] glace
[Termes IGN] image Landsat-TM
[Termes IGN] image NOAA-AVHRR
[Termes IGN] image Terra-MISR
[Termes IGN] image Terra-MODIS
[Termes IGN] neige
[Termes IGN] réflectance
[Termes IGN] transfert radiatifRésumé : (Auteur) In this paper, we propose equations for narrowband-to-broadband (NTB) albedo conversion for glacier ice and snow for four types of satellite sensors : thematic mapper (TM), advanced very high resolution radiometer (AVHRR), moderate resolution imaging spectroradiometer (MODIS), and multi-angle imaging spectroradiometer (MISR). We do this on the basis of spectral albedos and incident spectral irradiances generated with radiative-transfer models of the (sub)surface (a two-stream model) and the atmosphere, respectively. First, we establish equations for reference values of atmospheric components and the surface elevation. These equations describe measurements with root-mean-square differences of ~0.016. We then show that the "reference equations" also perform well when total ozone and aerosol optical depth are changed with respect to the reference. The negative effect of humidity and elevation variations on the performance of the equations can be eliminated by adding a correction term. We argue that narrowband albedos are much less sensitive to variations in the incident spectral irradiance than broadband albedos. Hence, our conclusions about the effects of variations in atmospheric composition and elevation are also valid for equations for NTB conversion proposed in other papers. Numéro de notice : A2004-010 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.rse.2003.10.010 En ligne : https://doi.org/10.1016/j.rse.2003.10.010 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=26538
in Remote sensing of environment > vol 89 n° 1 (15/01/2004) . - pp 95 - 105[article]Ground penetrating radar, 2nd edition / D.J. Daniels (2004)PermalinkQuantitative remote sensing of land surfaces / Shunlin Liang (2004)PermalinkRemote sensing in transition / Rudi Goossens (2004)PermalinkLa Terre vue de l'espace / Anny Cazenave (2004)PermalinkGeographical weighting as a further refinement to regression modelling: an example focused on the NDVI-rainfall relationship / Giles M. Foody in Remote sensing of environment, vol 88 n° 3 (15/12/2003)PermalinkSnow-cover mapping in forest by constrained linear spectral unimixing of MODIS data / D. Vikhamar in Remote sensing of environment, vol 88 n° 3 (15/12/2003)PermalinkAssessment of shoreline changes in the western side of Zanzibar channel using satellite remote sensing / Y.W. Shaghude in International Journal of Remote Sensing IJRS, vol 24 n° 23 (December 2003)PermalinkCharacterization of rainfall-induced landslides / F.C. Dai in International Journal of Remote Sensing IJRS, vol 24 n° 23 (December 2003)PermalinkFully polarimetric airborne SAR and ERS SAR observations of snow: implications for selection of Envisat ASAR modes / T. Guneriussen in International Journal of Remote Sensing IJRS, vol 24 n° 19 (October 2003)PermalinkCartographie des dépôts atmosphériques en France : deux approches pour les premières cartes nationales / L. Croise in Géomatique expert, n° 27 (01/09/2003)Permalink