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| 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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| Guerin, Charles-antoine; Soriano, Gabriel; Chapron, Bertrand. |
| A family of unified models in scattering from rough surfaces is based on local corrections of the tangent plane approximation through higher-order derivatives of the surface. We revisit these methods in a common framework when the correction is limited to the curvature, that is essentially the second-order derivative. The resulting expression is formally identical to the weighted curvature approximation, with several admissible kernels, however. For sea surfaces under the Gaussian assumption, we show that the weighted curvature approximation reduces to a universal and simple expression for the off-specular normalized radar cross-section ( NRCS), regardless of the chosen kernel. The formula involves merely the sum of the NRCS in the classical Kirchhoff... |
| Tipo: Text |
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| Ano: 2010 |
URL: http://archimer.ifremer.fr/doc/00018/12967/10148.pdf |
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