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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
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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
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