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Electromagnetic wave scattering from the sea surface in the presence of wind wave patterns / V. Shrira in International Journal of Remote Sensing IJRS, vol 24 n° 24 (December 2003)  

Public [article]  inInternational Journal of Remote Sensing IJRS > vol 24 n° 24 (December 2003) . - pp 5075 - 5093 Titre : Electromagnetic wave scattering from the sea surface in the presence of wind wave patterns Type de document : Article/Communication Auteurs : V. Shrira, Auteur ; S.I. Badulin, Auteur ; A.G. Voronovich, Auteur Année de publication : 2003 Article en page(s) : pp 5075 - 5093 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de télédétection [Termes IGN] analyse harmonique [Termes IGN] formule de Stokes [Termes IGN] géophysique externe [Termes IGN] interférence [Termes IGN] mer [Termes IGN] onde électromagnétique [Termes IGN] surface de la mer [Termes IGN] vent Résumé : (Auteur) The study is concerned with electromagnetic wave (EM) scattering by a random sea surface in the presence of coherent wave patterns. The coherent patterns are understood in a broad sense as the existence of certain dynamical coupling between linear Fourier components of the water wave field. We show that the presence of weakly nonlinear wave patterns can significantly change the EM scattering compared to the case of a completely random wave field. Generalizing the Random Phase Approximation (RPA) we suggest a new paradigm for EM scattering by a random sea surface. The specific analysis carried out in the paper synthesizes the small perturbation method for EM scattering and a weakly nonlinear approach for wind wave dynamics. By investigating, in detail, two examples of a random sea surface composed of either Stokes waves or horse-shoe ('crescent-shaped') patterns the mechanism of the pattern effect on scattering is revealed. Each Fourier harmonic of the scattered EM field is found to be a sum of contributions due to different combinations of wave field harmonics. Among these 'partial scatterings' there are phase-dependent ones and, therefore, the intensity of the resulting EM harmonic is sensitive to the phase relations between the wind wave harmonics. The effect can be interpreted as interference of partial scatterings due to the coexistence of several phase-related periodic scattering grids. A straightforward generalization of these results enables us to obtain, for a given wind wave field and an incident EM field, an a priori estimate of whether the effects due to the patterns are significant and the commonly used RPA is inapplicable. When the RPA is inapplicable, we suggest its natural generalization by re-defining the statistical ensemble for water surface. First, EM scattering by an 'elementary' constituent pattern should be considered. Each such scattering is affected by the interference because the harmonics comprising the pattern are dynamically linked. Then, ensemble averaging, which takes into account the distribution of the pattern parameters (based on the assumption that the phases between the patterns are random), should be carried out. It is shown that, generally, this interference does not vanish for any statistical ensemble due to dynamical coupling between water wave harmonics. The suggest RPA genralization takes into account weak non-Gaussianity of water wave field in contrast to the traditional RPA which ignores it. Numéro de notice : A2003-339 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1080/0143116031000095907 En ligne : https://doi.org/10.1080/0143116031000095907 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=22634 [article]

Exemplaires(1)

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Global structure of marine wind speed variability derived from Topex altimeter data / G. Chen in International Journal of Remote Sensing IJRS, vol 24 n° 24 (December 2003)  

Public [article]  inInternational Journal of Remote Sensing IJRS > vol 24 n° 24 (December 2003) . - pp 5119 - 5133 Titre : Global structure of marine wind speed variability derived from Topex altimeter data Type de document : Article/Communication Auteurs : G. Chen, Auteur ; S.W. Bi, Auteur ; J. Ma, Auteur Année de publication : 2003 Article en page(s) : pp 5119 - 5133 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image [Termes IGN] climat terrestre [Termes IGN] courant aérien [Termes IGN] données altimétriques [Termes IGN] données Topex-Poseidon [Termes IGN] géophysique externe [Termes IGN] océanographie spatiale [Termes IGN] Pacifique (océan) [Termes IGN] surface de la mer [Termes IGN] vague [Termes IGN] vent Résumé : (Auteur) As the largest source of momentum for the ocean surface, wind affects the full range, of oceanic motion-from individual surface waves to complete current systems. The marine surface wind is among the critical geophysical parameters which determine the most fundamental aspects of the ocean. Using six years (1993-1998) of TOPEX altimeter data with an unprecedented accuracy and continuity, a detailed investigation of the global structure of marine wind climatology and variability is carried out. It is found that the overall pattern of wind climatology is basically determined by solar radiation and therefore dominated by zonal features, while that of the wind variability is largely 'event' determined and thereby dominated by regional features. Consequently, wind climatology and wind variability show a complex relationship in their magnitude of intensity. Strong winds may be associated with high variabilities, such as in the westerlies of the North Atlantic and North Pacific; they may also be associated with low variabilities, such as in the westerlies of the Southern Ocean. Meanwhile, weak wind zones like the doldrums in the western equatorial Pacific can have a very low level of annual variability, while a very high level of interannual variability. The Asian monsoon system has a lower than average climatological mean speed, but exhibits extremely high annual variability. The phase distributions of wind variations carry combined information of climatology and variability. Effects of the Asian monsoon and marine storms are manifested on top of the basically zonal phase pattern. Statistics suggest that semiannual variability exceeds annual variability for 12.2% of the world's oceans, and interannual variability exceeds annual variability for 26.4% of the world's oceans. Numéro de notice : A2003-340 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1080/0143116031000082091 En ligne : https://doi.org/10.1080/0143116031000082091 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=22635 [article]

Exemplaires(1)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
080-03241	RAB	Revue	Centre de documentation	En réserve L003	Exclu du prêt

Evaluation of speckle noise MAP filtering algorithms applied to SAR images / F.N.S. Medeiros in International Journal of Remote Sensing IJRS, vol 24 n° 24 (December 2003)  

Public [article]  inInternational Journal of Remote Sensing IJRS > vol 24 n° 24 (December 2003) . - pp 5197 - 5218 Titre : Evaluation of speckle noise MAP filtering algorithms applied to SAR images Type de document : Article/Communication Auteurs : F.N.S. Medeiros, Auteur ; N.D.A. Mascarenhas, Auteur ; L.F. Costa, Auteur Année de publication : 2003 Article en page(s) : pp 5197 - 5218 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image [Termes IGN] analyse de groupement [Termes IGN] chatoiement [Termes IGN] filtrage du rayonnement [Termes IGN] filtre de déchatoiement [Termes IGN] limite de résolution radiométrique [Termes IGN] radar à antenne synthétique [Termes IGN] transformation de Hough Résumé : (Auteur) This work proposes new speckle reduction filters for multilook, amplitude detected Synthetic Aperture Radar (SAR) images based on the maximum a posteriori (MAP) approach and compares their performance. The new filters use an adaptive approach based on the one-dimensional k-means clustering algorithm over the variance ratio and also a regiongrowing procedure. The trade-off between the loss of radiometric resolution and edge preservation is evaluated in the filtered images. In order to obtain quantitative measures of the speckle reduction and of the edge blurring, we used some parameters such as the classical equivalent number of looks and the Hough transform. Experiments have been carried out with natural images corrupted with synthetic speckle noise following the Rayleigh and square root of gamma distributions and with real SAR images. Numéro de notice : A2003-341 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1080/0143116031000115148 En ligne : https://doi.org/10.1080/0143116031000115148 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=22636 [article]

Exemplaires(1)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
080-03241	RAB	Revue	Centre de documentation	En réserve L003	Exclu du prêt

Near real-time geocoding of SAR imagery with orbit error removal / A.J.E. Smith in International Journal of Remote Sensing IJRS, vol 24 n° 24 (December 2003)  

Public [article]  inInternational Journal of Remote Sensing IJRS > vol 24 n° 24 (December 2003) . - pp 5219 - 5228 Titre : Near real-time geocoding of SAR imagery with orbit error removal Type de document : Article/Communication Auteurs : A.J.E. Smith, Auteur Année de publication : 2003 Article en page(s) : pp 5219 - 5228 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image radar et applications [Termes IGN] correction géométrique [Termes IGN] erreur aléatoire [Termes IGN] géoréférencement [Termes IGN] image radar moirée [Termes IGN] orbitographie [Termes IGN] station de terrain mobile [Termes IGN] temps réel [Termes IGN] trajectographie (positionnement) Résumé : (Auteur) When utilizing knowledge of the spacecraft trajectory for near realtime geocoding of Synthetic Aperture Radar (SAR) images, the main problem is that predicted satellite orbits have to be used, which may be in error by several kilometres. As part of the development of a Dutch autonomous mobile ground station to receive and process satellite SAR data, a method has been developed that removes the effects of orbit errors from the computed azimuth and slantrange coordinates, whilst maintaining the realtime character. Results show that predicted orbits can be used to geocode SAR imagery in near real time with the same accuracy as when using precise orbits, i.e. 30-40 m. Numéro de notice : A2003-342 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1080/0143116031000114815 En ligne : https://doi.org/10.1080/0143116031000114815 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=22637 [article]

Exemplaires(1)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
080-03241	RAB	Revue	Centre de documentation	En réserve L003	Exclu du prêt

Radar stereo- and interferometry-derived digital elevation models: comparison and combination using Radarsat and ERS-2 imagery / M. Gelautz in International Journal of Remote Sensing IJRS, vol 24 n° 24 (December 2003)  

Public [article]  inInternational Journal of Remote Sensing IJRS > vol 24 n° 24 (December 2003) . - pp 5243 - 5264 Titre : Radar stereo- and interferometry-derived digital elevation models: comparison and combination using Radarsat and ERS-2 imagery Type de document : Article/Communication Auteurs : M. Gelautz, Auteur ; P. Paillou, Auteur ; C.W. Chen, Auteur ; H. Zebker, Auteur Année de publication : 2003 Article en page(s) : pp 5243 - 5264 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image radar et applications [Termes IGN] acquisition d'images [Termes IGN] analyse comparative [Termes IGN] histogramme [Termes IGN] image ERS-SAR [Termes IGN] image Radarsat [Termes IGN] interféromètrie par radar à antenne synthétique [Termes IGN] modèle numérique de surface [Termes IGN] modèle stéréoscopique [Termes IGN] pente Résumé : (Auteur) In this experiment, we derive and compare radar stereo and interferometric digital elevation models (DEMs) of a study site in Djibouti, East Africa. A Radarsat stereo pair, as well as Radarsat and ERS-2 interferometric data, comprise the test images. The primary objective of the study was to analyse and compare the results obtained by the two techniques and explore possible synergisms between them. We find that in regions of high coherence, the DEMs produced by interferometry are of much better quality than the stereo result. However, the corresponding error histograms also show some pronounced errors due to decorrelation and phase-unwrapping problems on forested mountain slopes. On the other hand, the more robust stereo reconstruction, with an error standard deviation of 45m, is able to capture the general terrain shape, although finer ' surface details are lost. In the second part of our experiment, we demonstrate that merging the stereoscopic and interferometric DEMs by applying a user-defined weighting function to a filtered coherence map can significantly improve the accuracy of the computed elevation maps Numéro de notice : A2003-343 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1080/0143116031000115139 En ligne : https://doi.org/10.1080/0143116031000115139 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=22638 [article]

Exemplaires(1)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
080-03241	RAB	Revue	Centre de documentation	En réserve L003	Exclu du prêt