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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

Extrapolation of the aerosol reflectance from the near-infrared to the visible : the single-scattering epsilon vs multiple-scattering epsilon method / M. Wang 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 3637 - 3650 Titre : Extrapolation of the aerosol reflectance from the near-infrared to the visible : the single-scattering epsilon vs multiple-scattering epsilon method Type de document : Article/Communication Auteurs : M. Wang, Auteur Année de publication : 2004 Article en page(s) : pp 3637 - 3650 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image optique [Termes IGN] aérosol [Termes IGN] atmosphère terrestre [Termes IGN] bande visible [Termes IGN] correction atmosphérique [Termes IGN] correction d'image [Termes IGN] diffusion du rayonnement [Termes IGN] exitance spectrale [Termes IGN] image Seawifs [Termes IGN] radiance [Termes IGN] rayonnement proche infrarouge Résumé : (Auteur) In the atmospheric correction algorithm for Sea-viewing Wide Fieldof-view Sensor, the effects of the spectral variation of the aerosol radiance contributions at the two near-infrared (NIR) bands are estimated directly from sensor-measured radiance. The aerosol effects at the NIR are then extrapolated into, the visible through a process of aerosol model selection from evaluation of the NIR single-scattering epsilon value, which is defined as the ratio of the single-scattering aerosol reflectance between two NIR bands. The aerosol radiance contribution at the visible wavelengths is then removed. In this paper, a slightly different approach in the aerosol model selection and extrapolation, i.e. using the NIR multiple-scattering epsilon instead of the single-scattering epsilon, is examined. The NIR multiple-scattering epsilon is the ratio of the aerosol multiple-scattering reflectance between two NIR wavelengths. Simulations show that, in general, both methods give comparable results. Statistically, more than 95% of cases in the retrieved ocean colour spectrum are within required accuracy for both methods. For clear atmosphere, however, the results of the atmospheric correction using the single-scattering epsilon method usually performed slightly better than the multiple-scattering epsilon method. On the other hand, for the large aerosol optical thickness the multiple-scattering epsilon method has slightly better retrievals for the Tropospheric aerosols. Some detailed analyses and discussions are provided to explain differences in these two approaches for extrapolating and retrieving the aerosol effects in the visible. Numéro de notice : A2004-355 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1080/01431160310001619599 En ligne : https://doi.org/10.1080/01431160310001619599 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=26882 [article]

Exemplaires(1)

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

An assessment of the effectiveness of atmospheric correction algorithms through the remote sensing of some reservoirs / D.G. Hadjimitsis 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 3651 - 3674 Titre : An assessment of the effectiveness of atmospheric correction algorithms through the remote sensing of some reservoirs Type de document : Article/Communication Auteurs : D.G. Hadjimitsis, Auteur ; C.R.I. Clayton, Auteur Année de publication : 2004 Article en page(s) : pp 3651 - 3674 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image optique [Termes IGN] aéroport [Termes IGN] analyse comparative [Termes IGN] bande visible [Termes IGN] correction atmosphérique [Termes IGN] effet atmosphérique [Termes IGN] image Landsat-TM [Termes IGN] image multibande [Termes IGN] Londres [Termes IGN] radiance [Termes IGN] radiomètre multibande [Termes IGN] réflectance [Termes IGN] spectroradiomètre Résumé : (Auteur) Although satellite remote sensing techniques have been widely implemented for a variety of applications, using either single or time-series images, few studies have explicitly considered atmospheric effects, and how they can most effectively be minimized. Despite the considerable number of available atmospheric correction algorithms, there is little literature concerning their relative merits. Over water bodies, atmospheric effects account for the majority of the at-satellite measured radiance in the visible bands, and therefore targets of this type provide an opportunity for assessing the effectiveness of the different methods available. This paper reports a study of atmospheric effects and their correction, using multi-spectral satellite remote sensing data for an area to the west of London that includes eight large water reservoirs and a major international airport (Heathrow). Through comparisons of reflectance within a time series of 12 Landsat-5 Thematic Mapper (TM) images, the overall impact of atmospheric contributions is shown. The available atmospheric correction literature is then reviewed, and the methods applied to the satellite imagery of the reservoirs. The results are compared with reflectances acquired using a field spectro-radiometer. A critical appraisal of the results, and of problems encountered in applying the various methods, leads to an evaluation of their value in practice. Numéro de notice : A2004-356 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1080/01431160310001647993 En ligne : https://doi.org/10.1080/01431160310001647993 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=26883 [article]

Exemplaires(1)

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

Satellite constellation with direct radio measurements for atmospheric studies : WATS mission case / G. Alberti 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 3703 - 3730 Titre : Satellite constellation with direct radio measurements for atmospheric studies : WATS mission case Type de document : Article/Communication Auteurs : G. Alberti, Auteur ; G.B. Amata, Auteur ; F. Amisano, Auteur Année de publication : 2004 Article en page(s) : pp 3703 - 3730 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Missions spatiales [Termes IGN] Agence spatiale européenne [Termes IGN] antenne [Termes IGN] distribution spatiale [Termes IGN] étude de faisabilité [Termes IGN] mission spatiale [Termes IGN] onde radioélectrique [Termes IGN] orbite basse [Termes IGN] positionnement par GNSS [Termes IGN] radiooccultation [Termes IGN] rayonnement électromagnétique [Termes IGN] rayonnement radioélectrique [Termes IGN] récepteur [Termes IGN] réfraction atmosphérique [Termes IGN] stratosphère [Termes IGN] teneur en vapeur d'eau [Termes IGN] transmission de données [Termes IGN] troposphère [Termes IGN] vapeur d'eau [Termes IGN] vent [Termes IGN] Water Vapour and Wind in Atmospheric Troposphere and Stratosphere Résumé : (Auteur) This paper shows the main results of a pre-feasibility study commissioned by the European Space Agency (ESA) in the framework of the Earth Explorer Core Mission programme. The analysed mission is called WATS (Water vapour and wind in Atmospheric Troposphere and Stratosphere) and aims to monitor variations and changes in the global atmospheric water vapour distribution and lower-stratosphere/upper-troposphere winds. Starting from a set of scientific requirements, the present work shows the main results of the mission analysis in terms of the number and spatial distribution of possible measurements. By performing trade-off with respect to expected values, the number of satellites forming the constellation has been fixed as well as the main orbital parameters, also taking into account degradations within the maximum expected mission lifetime. To assess the accuracy of the final measurement, a suitable performance model has been established that takes into account the effects of both the radio propagation of the signal through the atmosphere and the instrument receiving chain. The results obtained by running such a performance model are presented and discussed in order to assess the main system parameters mainly in terms of minimum transmitted power. Following, a sensitivity analysis is presented that shows the effects of antenna pointing error, receiver gain fluctuation, effective antenna size and pre-detection bandwidth. Numéro de notice : A2004-357 Affiliation des auteurs : non IGN Thématique : IMAGERIE/POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1080/01431160410001680392 En ligne : https://doi.org/10.1080/01431160410001680392 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=26884 [article]

Exemplaires(1)

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

Single frequency processing of atmospheric radio occultations / M. De La Torre Juarez 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 3731 - 3734 Titre : Single frequency processing of atmospheric radio occultations Type de document : Article/Communication Auteurs : M. De La Torre Juarez, Auteur ; E.R. Kursinski, Auteur ; et al., Auteur Année de publication : 2004 Article en page(s) : pp 3731 - 3734 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image [Termes IGN] atmosphère terrestre [Termes IGN] correction ionosphérique [Termes IGN] dégradation du GPS [Termes IGN] données GPS [Termes IGN] radiooccultation [Termes IGN] rapport signal sur bruit [Termes IGN] réfraction atmosphérique [Termes IGN] signal GPS Résumé : (Auteur) Tracking of the radio signals broadcast by the Global Positioning System (GPS) satellites as they are occulted from a GPS receiver by the Earth's atmosphere can provide high resolution vertical profiles of atmospheric refractivity, temperature and water vapour. Most implementations of this radio occultation technique use two GPS frequencies to correct for ionospheric effects. However, during most soundings, one of the frequencies is degraded by the introduction of the so-called Anti-Spoofing (AS) encryption mode. A retrieval method is discussed in this work for periods when only one of the two frequency signals has good quality. This method uses only the frequency with higher signal-to-noise ratio. We illustrate the quality of the atmospheric profiles obtained from such single frequency retrievals using GPS/MET data from the periods where the AS was turned off and the two frequencies were available. The results enable us to ensure the quality of a climate record of thousands of radio occultations collected by GPS/MET during the period with AS encryption, and the data processing of future missions with similar constraints, like IOX, can be performed. Numéro de notice : A2004-358 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1080/0143116031000156800 En ligne : https://doi.org/10.1080/0143116031000156800 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=26885 [article]

Exemplaires(1)

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