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Modélisation de l'interaction cohérente des ondes électromagnétiques avec des couverts forestiers

Abstract : The use of vegetation scattering models enable to better understand the links between radar data and the characteristics of the scene under observation. Recent studies have shown the point in modelling partially or totally the coherent interactions among scatterers. Thus, scattering models have evolved from an incoherent formulation (intensity) to a coherent one (amplitude and phase). In this thesis, a coherent and fully polarimetric formulation of the radar scattering of forested areas is developed. The canonical elements (cylinders and ellipsoids) are first considered in order to highlight the validity domain of the modelling of their interaction with electromagnetic waves. The coherent model is then presented and applied to a forest, considered as a discrete medium. The scattering by the whole forest results in the coherent sum of the fields scattered by each of its component. Each contribution is weighted by a phase shift induced by the relative position of the scatterers and weakened by the complex attenuation encountered by the wave during the propagation through the forest. Coherent models need a quite realistic description of the highlighted area, so the modelling of the forested areas have been carefully treated. This formulation is applied to two kinds of forests (tropical and tempered one) and considering three frequency bands (P-, L- and C- band). Studies of Mangrove forests stands show that the backscattering coefficient is correctly simulated, specially in the case where strong coherent effects are expected. Restrictions of this code have been analysed, particularly for high frequencies/densities. Finally the interferometric coherence is studied and its composition (influence of scatterers or mechanisms) is studied.
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Contributor : Laetitia Thirion <>
Submitted on : Thursday, December 18, 2003 - 12:03:17 PM
Last modification on : Friday, January 10, 2020 - 9:09:04 PM
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Laetitia Thirion. Modélisation de l'interaction cohérente des ondes électromagnétiques avec des couverts forestiers. Autre. Université Paul Sabatier - Toulouse III, 2003. Français. ⟨tel-00004022⟩

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