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	Provedor de dados ArchiMer (3) Autor Guerin, Charles-antoine (3) Nouguier, Frederic (3) Soriano, Gabriel (2) Chapron, Bertrand (1) Palavra-chave Remote sensing (3) Rough surfaces (3) Scattering (3) Doppler spectrum (2) Microwave (2) Nonlinear gravity waves (2) Sea surface (2) Gravity waves (1) Sea clutter (1) Undressed spectrum (1) Mais... Tipo do documento Text (3) Ano 2011 (2) 2010 (1) País France (3) Idioma Inglês (3)		Ordenar por:  Relevância Autor Título Ano Registros recuperados: 3 Primeira ... 1 ... Última Analytical Techniques for the Doppler Signature of Sea Surfaces in the Microwave Regime-I: Linear Surfaces ArchiMer Nouguier, Frederic; Guerin, Charles-antoine; Soriano, Gabriel. This paper is the first in a series of two papers on the use of combined improved hydrodynamic and electromagnetic analytical models for the simulation of the ocean Doppler spectrum at microwave frequencies. Under a linear assumption for the sea surface, we derive statistical expression for the main Doppler characteristics according to asymptotic scattering models. We consider classical models such as the Kirchhoff approximation and the two-scale model, as well as the more recent weighted curvature approximation (WCA). We recover two salient features of Doppler signature in the microwave regime. First, the Doppler characteristics are very sensitive to polarization, with higher mean Doppler shift in horizontal polarization. This is correctly rendered by the... Tipo: Text Palavras-chave: Doppler spectrum; Gravity waves; Microwave; Remote sensing; Rough surfaces; Scattering; Sea surface. Ano: 2011 URL: http://archimer.ifremer.fr/doc/00054/16524/14379.pdf Analytical Techniques for the Doppler Signature of Sea Surfaces in the Microwave Regime-II: Nonlinear Surfaces ArchiMer Nouguier, Frederic; Guerin, Charles-antoine; Soriano, Gabriel. This paper extends the results of a previous work by combining hydrodynamic and electromagnetic analytical models for the simulation of the ocean Doppler spectrum at microwave frequencies. We consider weakly nonlinear sea surfaces after the choppy wave model and incorporate them in classical and unified scattering models, namely, the Kirchhoff and weighted curvature approximations. We show that statistical expressions can be obtained for the Doppler spectrum in a way similar to the case of linear surfaces. As expected, the nonlinear nature of the sea surface dramatically impacts the Doppler spectrum at moderate to large incidence angles, with a shift of the central frequency and a broadening of the spectrum. Monte Carlo comparisons are performed with the... Tipo: Text Palavras-chave: Doppler spectrum; Microwave; Nonlinear gravity waves; Remote sensing; Rough surfaces; Scattering; Sea surface. Ano: 2011 URL: http://archimer.ifremer.fr/doc/00054/16555/14380.pdf Scattering From Nonlinear Gravity Waves: The "Choppy Wave" Model ArchiMer Nouguier, Frederic; Guerin, Charles-antoine; Chapron, Bertrand. To progress in the understanding of the impact of nonlinear wave profiles in scattering from sea surfaces, a nonlinear model for infinite-depth gravity waves is considered. This model, termed as the "Choppy Wave" Model (CWM), is based on horizontal deformation of a linear reference random surface. It is numerically efficient and enjoys explicit second-order statistics for height and slope, which makes it well adapted to a large family of scattering models. We incorporate the CWM into a Kirchhoff or small-slope approximation and derive statistical expressions for the corresponding incoherent cross section. We insist on the importance of "undressing" the wavenumber spectrum to generate a nonlinear surface with a prescribed spectrum. Interestingly, the... Tipo: Text Palavras-chave: Nonlinear gravity waves; Remote sensing; Rough surfaces; Scattering; Sea clutter; Undressed spectrum. Ano: 2010 URL: http://archimer.ifremer.fr/doc/00018/12974/10175.pdf Registros recuperados: 3 Primeira ... 1 ... Última

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