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Multi-technique comparison of tropospheric zenith delays derived during the CONT02 campaign / Pascal Willis in Journal of geodesy, vol 79 n° 10-11 (February 2006)
[article]
Titre : Multi-technique comparison of tropospheric zenith delays derived during the CONT02 campaign Type de document : Article/Communication Auteurs : Pascal Willis , Auteur ; K. Snajdrova, Auteur ; Johannes Böhm , Auteur ; Rüdiger Haas, Auteur Année de publication : 2006 Article en page(s) : pp 613 - 623 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique
[Termes IGN] analyse comparative
[Termes IGN] distance zénithale
[Termes IGN] données WVR
[Termes IGN] écart type
[Termes IGN] erreur systématique
[Termes IGN] météorologie
[Termes IGN] positionnement par DORIS
[Termes IGN] positionnement par GPS
[Termes IGN] prévision météorologique
[Termes IGN] propagation troposphérique
[Termes IGN] traitement du signal
[Termes IGN] troposphèreRésumé : (Auteur) In October 2002, 15 continuous days of Very Long Baseline Interferometry (VLBI) data were observed in the Continuous VLBI 2002 (CONT02) campaign. All eight radio telescopes involved in CONT02 were co-located with at least one other space-geodetic technique, and three of them also with a Water Vapor Radiometer (WVR). The goal of this paper is to compare the tropospheric zenith delays observed during CONT02 by VLBI, Global Positioning System (GPS), Doppler Orbitography Radiopositioning Integrated by Satellite (DORIS) and WVR and te, compare them also with operational pressure level data from the European Centre for Medium-Range Weather Forecasts (ECMWF). We show that the tropospheric zenith delays from VLBI and GPS are in good agreement at the 3-7 mm level. However, while only small biases can be found for most of the stations, at Kokee Park (Hawaii, USA) and Westford (Massachusetts, USA) the zenith delays derived by GPS are larger by more than 5 mm than those from VLBI. At three of the four DORIS stations, there is also a fairly good agreement with GPS and VLBI (about 10 mm), but at Kokee Park the agreement is only at about 30 mm standard deviation, probably due to the much older installation and type of DORIS equipment. This comparison also allows testing of different DORIS analysis strategies with respect to their real impact on the precision of the derived tropospheric parameters. Ground truth information about the zenith delays can also be obtained from the ECMWF numerical weather model and at three sites using WVR measurements, allowing for comparisons with results from the space-geodetic techniques. While there is a good agreement (with some problems mentioned above about DORIS) among the space-geodetic techniques, the comparison with WVR and ECMWF is at a lower accuracy level. The complete CONT02 data set is sufficient to derive a good estimate of the actual precision and accuracy of each geodetic technique for applications in meteorology. Numéro de notice : A2006-088 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-005-0010-z En ligne : https://doi.org/10.1007/s00190-005-0010-z Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=27815
in Journal of geodesy > vol 79 n° 10-11 (February 2006) . - pp 613 - 623[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 266-06012 RAB Revue Centre de documentation En réserve L003 Disponible 266-06011 RAB Revue Centre de documentation En réserve L003 Disponible 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]Reconstruction of cloud geometry from multi-view satellite images / G. Seiz in Remote sensing of environment, vol 100 n° 2 (30 January 2006)
[article]
Titre : Reconstruction of cloud geometry from multi-view satellite images Type de document : Article/Communication Auteurs : G. Seiz, Auteur ; R. Davies, Auteur Année de publication : 2006 Article en page(s) : pp 143 - 149 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications photogrammétriques
[Termes IGN] hydrologie
[Termes IGN] image Terra-MISR
[Termes IGN] modèle de transfert radiatif
[Termes IGN] nuage
[Termes IGN] radiance
[Termes IGN] reconstruction 3DRésumé : (Auteur) Reflected solar radiances measured by the pushbroom cameras of the Multiangle Imaging SpectroRadiometer (MISR) on the Terra satellite at nine viewing angles are combined to give eight stereo pairs. These are analyzed with stereo-photogrammetric methods to measure the geometry of a convective cloud system. Both cloud-top heights and cloud sides are retrieved with a precision of about 200-300 m. Two case studies of deep, convective clouds over ocean are considered. The accuracy of the MISR retrieval is tested in the first case study by reference to coincident, higher resolution stereo data from ASTER, showing how the accuracy of the cloud-top height retrieval is improved using the oblique MISR views. In the second case study, the entire cross-section of the cloud aligned with the viewing azimuthal direction is measured, using all nine cameras. The methodology presented is an important step towards more routine retrievals of the 3D geometrical reconstruction of isolated, deep-convective clouds. Such reconstructions are a necessary prerequisite to the subsequent 3D radiative transfer modeling used to aid the remote sensing of the elusive microphysical properties of such clouds. Numéro de notice : A2006-033 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.rse.2005.09.016 En ligne : https://doi.org/10.1016/j.rse.2005.09.016 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=27760
in Remote sensing of environment > vol 100 n° 2 (30 January 2006) . - pp 143 - 149[article]Estimating accuracy in optimal deconvolution of synthetic AMSR-E observations / A.S. Limaye in Remote sensing of environment, vol 100 n° 1 (15/01/2006)
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Titre : Estimating accuracy in optimal deconvolution of synthetic AMSR-E observations Type de document : Article/Communication Auteurs : A.S. Limaye, Auteur ; William L. Crosson, Auteur ; C.A. Laymon, Auteur Année de publication : 2006 Article en page(s) : pp 133 - 142 Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image
[Termes IGN] déconvolution
[Termes IGN] eau de surface
[Termes IGN] image Aqua-AMSR
[Termes IGN] télédétection en hyperfréquence
[Termes IGN] température de luminanceRésumé : (Auteur) Optimal deconvolution (ODC) utilizes the footprint overlap in microwave observations to estimate the earth's brightness temperatures (TB ). This paper examines the accuracy of ODC estimated TB compared with a standard averaging technique. Because brightness temperatures cannot be independently verified, we constructed synthetic True TB for accuracy assessment. We assigned TB at a high spatial resolution (1 km) grid and computed the True TB by spatial averaging of the assigned TB to a lower resolution earth grid (25 km), selected to match the resolution of products generated from the Advanced Microwave Scanning Radiometer for the Earth Observing System (AMSRE). We used the sensor antenna response function along with the 1km assigned TB to generate synthetic observations at AMSRE footprint locations. These synthetic observations were subsequently deconvolved in the ODC technique to estimate TB at the lower resolution earth grid. The ODC estimated TB and the simple grid cell averages of the synthetic observations were compared with the True TB allowing us to quantify the efficacy of each technique. In areas of high TB contrast (such as boundaries of water bodies), ODC performed significantly better than averaging. In other areas, ODC and averaging techniques produced similar results. A technique similar to ODC can be effective in delineating water bodies with significant clarity. That will allow microwave observations to be utilized near the shorelines, a trouble spot for the currently used averaging techniques. Numéro de notice : A2006-015 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.rse.2005.10.008 En ligne : https://doi.org/10.1016/j.rse.2005.10.008 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=27742
in Remote sensing of environment > vol 100 n° 1 (15/01/2006) . - pp 133 - 142[article]Utilizing calibrated GPS reflected signals to estimate soil reflectivity and dielectric constant: results from SMEX02 / S.J. Katzberg in Remote sensing of environment, vol 100 n° 1 (15/01/2006)
[article]
Titre : Utilizing calibrated GPS reflected signals to estimate soil reflectivity and dielectric constant: results from SMEX02 Type de document : Article/Communication Auteurs : S.J. Katzberg, Auteur ; O. Torres, Auteur ; et al., Auteur Année de publication : 2006 Article en page(s) : pp 17 - 28 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale
[Termes IGN] bande L
[Termes IGN] constante diélectrique
[Termes IGN] données de terrain
[Termes IGN] étalonnage géométrique
[Termes IGN] humidité du sol
[Termes IGN] Iowa (Etats-Unis)
[Termes IGN] réflectance de surface
[Termes IGN] réflectivité
[Termes IGN] réflexion spéculaire
[Termes IGN] signal GPS
[Termes IGN] Soil Moisture Experiment
[Termes IGN] sol arable
[Termes IGN] télédétection en hyperfréquenceRésumé : (Auteur) Extensive reflected GPS data was collected using a GPS reflectometer installed on an HC130 aircraft during the Soil Moisture Experiment 2002 (SMEX02) near Ames, Iowa. At the same time, widespread surface truth data was acquired in the form of point soil moisture profiles, areal sampling of near-surface soil moisture, total green biomass and precipitation history, among others. Previously, there have been no reported efforts to calibrate reflected GPS data sets acquired over land. This paper reports the results of two approaches to calibration of the data that yield consistent results. It is shown that estimating the strength of the reflected signals by either (1) assuming an approximately specular surface reflection or (2) inferring the surface slope probability density and associated normalization constants give essentially the saine results for the conditions encountered in SMEX02. The corrected data is converted to surface reflectivity and then to dielectric constant as a test of the calibration approaches. Utilizing the extensive in-situ soil moisture related data, this paper also presents the results of comparing the GPS-inferred relative dielectric constant with the Wang - Schmugge model frequently used to relate volume moisture content to dielectric constant. It is shown that the calibrated GPS reflectivity estimates follow the expected dependence of permittivity with volume moisture, but with the following qualification: The soil moisture value governing the reflectivity appears to come from only the top 1 - 2 cm of soil, a result consistent with results found for other microwave techniques operating at L-band. Nevertheless, the experimentally derived dielectric constant is generally lower than predicted. Possible explanations are presented to explain this result. Numéro de notice : A2006-014 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.rse.2005.09.015 En ligne : https://doi.org/10.1016/j.rse.2005.09.015 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=27741
in Remote sensing of environment > vol 100 n° 1 (15/01/2006) . - pp 17 - 28[article]An inverse radiative transfer model to extract ground spectral reflectance of urban areas / Sophie Lacherade (2006)PermalinkApports de l'imagerie satellitaire à la mise à jour de l'information géographique dans les pays de la ceinture tropicale / J.L. Kouame (2006)PermalinkAssessment of the potential of MERIS near-infrared water vapour products to correct ASAR interferometric measurements / Z. Li in International Journal of Remote Sensing IJRS, vol 27 n°1-2 (January 2006)PermalinkPermalinkEinführung in die Spektral- und Zeitreihenanalyse mit Beispielen aus der Geodäsie / A. Teusch (2006)PermalinkElaboration de MNT par extraction de pentes topographiques de données polarimétriques / Yohann Ly (2006)PermalinkEtude de différents facteurs influant les classifications d'images multi-résolution / F. Kazemipour (2006)PermalinkObservations multi-paramètres et modélisation de la signature ionosphérique du grand séisme de Sumatra / Giovanni Occhipinti (2006)PermalinkPermalinkPotentiel de la mesure GPS sol pour l’étude des pluies intenses méditerranéennes / Hugues Brenot (2006)Permalink