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Continental scale hotspot observations of Australia at sub-degree angular resolution from POLDER / F. Grant in International Journal of Remote Sensing IJRS, vol 25 n° 18 (September 2004)  

Public [article]  inInternational Journal of Remote Sensing IJRS > vol 25 n° 18 (September 2004) . - pp 3625 - 3636 Titre : Continental scale hotspot observations of Australia at sub-degree angular resolution from POLDER Type de document : Article/Communication Auteurs : F. Grant, Auteur ; C. Heyraud, Auteur ; François-Marie Bréon, Auteur Année de publication : 2004 Article en page(s) : pp 3625 - 3636 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image [Termes IGN] analyse comparative [Termes IGN] Australie [Termes IGN] bande spectrale [Termes IGN] carte de la végétation [Termes IGN] image ADEOS-POLDER [Termes IGN] réflectance végétale [Termes IGN] tâche claire Résumé : (Auteur) Angular signatures of the innermost few degrees of the hotspot are retrieved on Australian land surfaces with an angular resolution better than 0.5° and a spatial resolution of around 150 km, using data from the Polarization and Directionality of the Earth's Reflectances (POLDER) instrument on the Advanced Earth Observing Satellite (ADEOS). These constitute the first comprehensive hotspot measurements at the scale of a continent. The retrieval technique requires that the hotspot characteristics at small angular scales are approximately invariant over a region of about 50km in extent, but accommodates pixel-to-pixel variations in the other characteristics, of the angular signature. Continental maps of the amplitude and half-width of the hotspot, in two spectral bands, are presented for two 41-day orbit cycles in different seasons and compared with a vegetation map. The half-widths are predominantly in the range 0.5°-1.5°, with no systematic difference between the 670 nm and 865 nm bands, and show little spatial structure. The maps of hotspot amplitude display significant spatial structure that corresponds closely to the vegetation map. Generally, areas of trees and tall shrubs are characterized by low hotspot amplitudes, while cropland, grassland and areas of low shrubs have high hotspot amplitudes. The evergreen broadleaf eucalypt forests are notable in that the amplitude is low at 670 nm and high at 865 nm. Numéro de notice : A2004-354 Affiliation des auteurs : non IGN Thématique : FORET/IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1080/01431160310001648000 En ligne : https://doi.org/10.1080/01431160310001648000 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=26881 [article]

Exemplaires(1)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
080-04161	RAB	Revue	Centre de documentation	En réserve L003	Exclu du prêt

Bidirectional reflectance of Earth targets: evaluation of analytical models using a large set of spaceborne measurements with emphasis on the Hot Spot / F. Maignan in Remote sensing of environment, vol 90 n° 2 (30/03/2004)  

Public [article]  inRemote sensing of environment > vol 90 n° 2 (30/03/2004) . - pp 210 - 220 Titre : Bidirectional reflectance of Earth targets: evaluation of analytical models using a large set of spaceborne measurements with emphasis on the Hot Spot Type de document : Article/Communication Auteurs : F. Maignan, Auteur ; François-Marie Bréon, Auteur ; R. Lacaze, Auteur Année de publication : 2004 Article en page(s) : pp 210 - 220 Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Rayonnement électromagnétique [Termes IGN] albedo [Termes IGN] distribution du coefficient de réflexion bidirectionnelle BRDF [Termes IGN] image ADEOS-POLDER [Termes IGN] réflectance [Termes IGN] rétrodiffusion [Termes IGN] tâche claire [Termes IGN] transfert radiatif Résumé : (Auteur) Multidirectional observation from the spacebome POLDER (Polarization and Directionality of the Earth Reflectance) instrument makes it possible to measure the bidirectional reflectance of a large variety of Earth targets. A careful selection of cloud-free measurements with a large directional coverage lead to about 22,000 sets of measured Bidirectional Reflectance Distribution Functions (BRDFs). This data set is used to evaluate the ability of analytical models to reproduce the observed directional signatures. Among those evaluated, the best models appear to be the three-parameter linear Ross-Li model, and the nonlinear Rahman-Pinty-Verstraete (RPV) model. On the other hand, all models fail to accurately reproduce the sharp reflectance increase (hot spot) close to the backscattering direction. Based on physical considerations, we suggest a modification of the Ross-Li model, without adding a free parameter, to account for the complex radiative transfer within the canopy that leads to the hot spot signature. The modified linear model performs better than all others, including the RPV nonlinear model. Although the correction modifies the retrieved directional signature parameters, it does not change significantly the surface albedo estimates. Numéro de notice : A2004-142 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.rse.2003.12.006 En ligne : https://doi.org/10.1016/j.rse.2003.12.006 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=26669 [article]

Mapping the aerodynamic roughness length of desert surfaces from the POLDER/ADEOS bi-directional reflectance product / Béatrice Marticorena in International Journal of Remote Sensing IJRS, vol 25 n° 3 (February 2004)  

Public [article]  inInternational Journal of Remote Sensing IJRS > vol 25 n° 3 (February 2004) . - pp 603 - 626 Titre : Mapping the aerodynamic roughness length of desert surfaces from the POLDER/ADEOS bi-directional reflectance product Type de document : Article/Communication Auteurs : Béatrice Marticorena, Auteur ; Patrick Chazette, Auteur ; G. Bergametti, Auteur ; et al., Auteur Année de publication : 2004 Article en page(s) : pp 603 - 626 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de télédétection [Termes IGN] carte thématique [Termes IGN] distribution du coefficient de réflexion bidirectionnelle BRDF [Termes IGN] image ADEOS [Termes IGN] POLarization and Directionality of Earth's Reflectances [Termes IGN] poussière [Termes IGN] réflectance de surface [Termes IGN] rugosité [Termes IGN] Sahara, désert du [Termes IGN] zone aride Résumé : (Auteur) Surface roughness is a key parameter for computing the emissions and for simulating the atmospheric cycle of mineral dust. However its assessment on the basis of field measurements from source areas scattered round the globe requires much effort. Here we investigate the retrieval of the aerodynamic roughness length of and areas using surface bi-directional reflectance products derived from passive multi-directional measurements in the solar spectrum of the POlarization and Directionality of the Earth's Reflectances (POLDER) sensor. The so-called protrusion coefficient (PC) of the surface derived from the POLDER bidirectional reflectance distribution function (BRDF) is well suited to estimate surface roughness. From an appropriate selection of POLDER data, a composite PC dataset has been established over the Sahara and the Arabian Peninsula. We have investigated the relationship between aerodynamic roughness length and PC, and have derived a statistically significant empirical relationship between these two parameters. This relationship is applied to the POLDER-derived PC to map the aerodynamic roughness length of and areas in northern Africa and the Arabian Peninsula at the spatial resolution of POLDER (- 1/16). When degrading these data for global models, we show that the information is essentially preserved at coarser resolutions up to . This map of roughness length derived from the POLDER instrument, and a corresponding map derived from a geomorphologic classification, have been tested by comparing the predicted dust event frequencies obtained using them to dust indices (IDDI) derived from Meteosat IR observations over the Sahara desert. The agreement using the POLDER derived roughness length is at least as good as using the map of roughness length derived from the geomorphologic approach. Our results show promising new prospects for regional and global scale simulations of mineral dust emissions from and regions. Numéro de notice : A2004-065 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1080/0143116031000116976 En ligne : https://doi.org/10.1080/0143116031000116976 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=26593 [article]

Exemplaires(1)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
080-04031	RAB	Revue	Centre de documentation	En réserve L003	Exclu du prêt