The weighted curvature approximation in scattering from sea surfaces

Guérin, Charles-Antoine; Soriano, Gabriel; Chapron, Bertrand

doi:10.1080/17455030903563824

Cited by 44 publications

(41 citation statements)

References 16 publications

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“…The approach presented in this paper is based on the comparison between the polarization ratio measured by a radar operating at L-band and the values estimated by an analytical scattering model, namely the Universal Weighted Curvature Approximation (U-WCA), [22].…”

Section: Estimation Of Oil Concentration In An Oil-in-water Slick Emumentioning

confidence: 99%

“…In general, a precise knowledge of the local incidence angle is not available; an approximation from SAR data can be obtained from an uncovered area close to the oil slick assuming homogeneous large-scale phenomena over the entire imaged area [11]. To overcome this strong limitation, the use of the U-WCA scattering model allows estimation of the polarization ratio without requiring the knowledge of the locale incidence angle [21,22], resulting from the local tilt of the facets composing the sea surface. In this paper, the polarization ratio measured by a radar sensor is compared to those estimated by the U-WCA model, the difference over slick covered area being linked to the modification of the effective dielectric constant compared to the surrounding clean sea surface.…”

Section: The Universal Weighted Curvature Approximation Scattering Modelmentioning

confidence: 99%

“…The U-WCA scattering model [22] belongs to the family of so-called "unified models" [32], such as the Two Scale Models (TSM) [6,33] or the Small-Slope Approximation [34], that is models which are able to cope with both large scales and small ripples at the sea surface. The U-WCA model leads to non-trivial roughness-dependent PR but has the considerable advantage of a simple formulation involving the nominal incidence angle only and requiring no facet decomposition.…”

Section: The Universal Weighted Curvature Approximation Scattering Modelmentioning

confidence: 99%

Section: The Universal Weighted Curvature Approximation Scattering Modelmentioning

confidence: 99%

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Dual-Polarized L-Band SAR Imagery for Temporal Monitoring of Marine Oil Slick Concentration

2018

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SAR sensors are usually used in the offshore domain to detect marine oil slicks which allows the authorities to guide cleanup operations or prosecute polluters. As radar imagery can be used any time of day or year and in almost any weather conditions, the use and programming of such remote sensing data is usually favored over optical imagery. Nevertheless, images collected in the optical domain provide access to key information not accessible today by SAR instruments, such as the thickness or the amount of pollutant. To address this knowledge gap, a methodology based on the joint use of a scattering model (U-WCA) and remote sensing data collected by a low frequency (e.g., L-band) imaging radar over controlled release of mineral oil spill is reported in this paper. The proposed method allows estimation of the concentration of pollutant within an oil-in-water mixture as well as the temporal variation of this quantity due to weathering processes.

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Section: Estimation Of Oil Concentration In An Oil-in-water Slick Emumentioning

confidence: 99%

Section: The Universal Weighted Curvature Approximation Scattering Modelmentioning

confidence: 99%

Section: The Universal Weighted Curvature Approximation Scattering Modelmentioning

confidence: 99%

Section: The Universal Weighted Curvature Approximation Scattering Modelmentioning

confidence: 99%

See 2 more Smart Citations

Dual-Polarized L-Band SAR Imagery for Temporal Monitoring of Marine Oil Slick Concentration

2018

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“…Nouguier et al [43] have shown that adding hydrodynamical nonlinearities in the sea surface model impacts the mean Doppler shift but also and in a more important way the Doppler spectrum width. For such derivations, they used an asymptotic electromagnetic model, namely, the weighted curvature approximation (WCA) [44], [45], which discards complex electromagnetic interactions such as multiple reflections. In that case, the discrepancies observed between linear and nonlinear surfaces are explained by modulation and advection of the short Bragg waves by longer waves.…”

Section: Interpretation and Discussionmentioning

confidence: 99%

Sea Surface Microwave Scattering at Extreme Grazing Angle: Numerical Investigation of the Doppler Shift

Miret

Soriano

Nouguier

et al. 2014

IEEE Trans. Geosci. Remote Sensing

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Abstract-We present a numerical investigation of horizontally polarized microwave scattering from 1-D sea surfaces at extreme grazing angles. Rigorous electromagnetic calculations are performed with a specific integral formalism dedicated to grazing angles. Sample sea surfaces are simulated using a classical Pierson-Moskowitz elevation spectrum together with weakly nonlinear hydrodynamic models, namely, the Creamer solution, the "choppy wave model," and a recent improved version thereof. For this, the electromagnetic integral formalism is extended to surfaces with irregular sampling. For the different nonlinear surface models and assuming no large-scale current, we evidence a dramatic increase, followed by a saturation of the mean Doppler shift in the last few grazing degrees, with a limiting value depending quasilinearly on the significant wave height. Our numerical investigations confirm that breaking events are not necessary to produce fast scatterers but tend to show that they are necessary to reproduce the elevated level of backscattered power. The results of this study also support the hypothesis that the blow-up of the mean Doppler shift at grazing angle is associated to an electromagnetic sharp edge effect on the large surface crests rather than geometrical shadowing of the troughs.Index Terms-Doppler effect, method of moments, sea surface.

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Quad‐polarization SAR features of ocean currents

et al. 2014

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A methodology is demonstrated to exploit the polarization sensitivity of high-resolution radar measurements to interpret and quantify upper ocean dynamics. This study particularly illustrates the potential of quad-polarization synthetic aperture radar (SAR) measurements. The analysis relies on essential characteristics of the electromagnetic scattering mechanisms and hydrodynamical principles. As the relaxation scale of centimeter-scale ocean surface scatters is typically small, radar signal anomalies associated with surface manifestations of the upper ocean dynamics on spatial scales exceeding 100 m are mostly dominated by nonresonant and nonpolarized scatters. These ''scalar'' contributions can thus efficiently trace local breaking and near-breaking areas, caused by surface current variations. Using dual copolarized measurements, the polarized Bragg-type radar scattering is isolated by considering the difference (PD) between vertically and horizontally polarized radar signals. The nonpolarized (NP) contribution associated with wave breaking is then deduced, using the measured polarization ratio (PR) between polarized signals. Considering SAR scenes depicting various surface manifestations of the upper ocean dynamics (internal waves, mesoscale surface current features, and SST front), the proposed methodology and set of decompositions (PD, PR, and NP) efficiently enable the discrimination between surface manifestation of upper ocean dynamics and wind field variability. Applied to quad-polarized SAR images, such decompositions further provide unique opportunities to more directly assess the cross-polarized (CP for HV or VH) signal sensitivity to surface roughness changes. As demonstrated, such an analysis unambiguously demonstrates and quantitatively evaluates the relative impact of breakers on cross-polarized signals under low to moderate wind conditions.

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The weighted curvature approximation in scattering from sea surfaces

Cited by 44 publications

References 16 publications

Dual-Polarized L-Band SAR Imagery for Temporal Monitoring of Marine Oil Slick Concentration

Dual-Polarized L-Band SAR Imagery for Temporal Monitoring of Marine Oil Slick Concentration

Sea Surface Microwave Scattering at Extreme Grazing Angle: Numerical Investigation of the Doppler Shift

Quad‐polarization SAR features of ocean currents

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