Simulations of the bistatic scattering using two-scale model and the unified sea spectrum

Ayari, Mohamed

doi:10.1117/1.2787505

Cited by 17 publications

(7 citation statements)

References 11 publications

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“…Ayari et al studied the bistatic scattering of the sea surface using TSM and the Elfouhaily spectrum. In their work, the scattering coefficients calculated with TSM and the Elfouhaily spectrum were compared with those obtained with CMOD5, SSA, and the Pierson spectrum [21]. Du et al studied the backscattering from the sea surface with the advanced integral equation method, an improved angular spreading function, and Apel's omnidirectional spectrum [22].…”

Section: Introductionmentioning

confidence: 99%

Sea Surface Monostatic and Bistatic EM Scattering Using SSA-1 and UAVSAR Data: Numerical Evaluation and Comparison Using Different Sea Spectra

et al. 2018

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The microwave scatterometer is one of the most effective instruments in ocean remote sensing, which urges the need for some theoretical models to accurately estimate the scattering coefficient of the sea surface. For the simulation of the scattering from an ocean surface, the sea spectrum, or its inverse Fourier transform, autocorrelation function is essential. Currently, many sea spectral models have been proposed for describing sea waves. However, which spectrum should be adopted during electromagnetic (EM) computations? A systematic comparison of these models is needed to evaluate their accuracies. In this paper, we focus on numerical simulations of scattering from a rough sea surface in monostatic and bistatic configurations by using six different sea spectral models and the first-order small slope approximation (SSA-1). First, sea spectral models proposed by Elfouhaily et al., Hwang et al., Romeiser et al., Apel et al., Fung et al., and Pierson et al., are compared with each other from different points of view, e.g., the omnidirectional parts, the angular spreading functions, the autocorrelation functions, and the slope variances. We find that the spectra given by Elfouhaily and Hwang could reflect realistic wind sea waves more accurately. Then, the scattering coefficients are simulated in fully monostatic and bistatic configurations. Regarding the monostatic scattering, the results simulated using EM scattering models are compared with those obtained from the measured UAVSAR data in the L band and the empirical model CMOD5 in the C band. Comparisons are made for various incident angles, wind speeds, and wind directions. Meanwhile, special attention is paid to low to moderate incident angles. The comparisons show that, it is difficult to find one certain spectral model to simulate scattering coefficient accurately under all wind speeds or wind directions. Accurate estimations will be obtained using different methods according to different situations.

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Section: Introductionmentioning

confidence: 99%

Sea Surface Monostatic and Bistatic EM Scattering Using SSA-1 and UAVSAR Data: Numerical Evaluation and Comparison Using Different Sea Spectra

et al. 2018

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“…Compared with approximate approaches, numerical approaches [7,8], even their acceleration algorithms [9,10], have their inherent disadvantages-they are computationally demanding and time-consuming-so that they are often applied to one-dimensional sea surface and simple three-dimensional targets and are rarely applied to two-dimensional (2D) sea surface. Composite surface methods (CSM) or TSM [11,12] is an outstanding approximate approach to obtain accurate and acceptable results for 2D sea surface, which is developed from two basic approximate approaches-KA [13] and SPM [14]-and can extend the domain of validity of the two. Another effective method-small slope approximation (SSA) [15][16][17]-can be degenerated into the two while with similar accuracy to method of moment (MoM), which allows it to be the most common method to make comparison with, even with relatively higher computation complexity than other approximate approaches.…”

Section: Introductionmentioning

confidence: 99%

Angular Composite Facet Model with Shadowing Treatment for Backscattering from Two-Dimensional Rough Sea Surface

Wang

You²,

et al. 2019

Symmetry

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Recent diverse applications on ocean wave synthetic aperture radar (SAR) images have a potential demand for individual facet scattering contribution rather than the total average radar cross-section (RCS) by statistical scattering models. However, only a few facet methods have been proposed and fewer have considered shadowing effects, which are thought to be non-negligible at large incident angle. In view of this, we proposed an angular composite facet model (ACFM) with shadowing treatment to investigate the backscattering from two-dimensional rough sea surface. First, a region division formula for ACFM without shadowing treatment is proposed to classified sea surface facets into specular facets and diffusion facets based on which kind of scattering is dominate from each facet, and the corresponding scattering contribution is calculated either by Kirchhoff approximation (KA) or by a small perturbation method (SPM) with a tilting process. Second, an electromagnetic shadowing algorithm based on facets grouping is adopted to handle the shadowing effects in a geometric manner with moderate computation complexity gained. Finally, comparisons between numerical backscattering evaluations and experimental data demonstrate that this new ACFM can attain accurate numerical results and the geometric facets grouping method is a practical way to tackle shadowing effects despite a certain acceptable gap. Therefore, the whole ACFM can simulate ocean wave SAR imaging, especially for those electrically large surfaces and to evaluate the scattering from sea surface with different local nature, such as sea spikes, foams, spilled oil, swells, and ship wake.

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“…Among analytical approximate models, the Kirchhoff approximation [19][20][21] also known as the physical optics and the tangent plane approximation cannot correctly show distinct polarization dependence. The two-scale model [22,23] also known as composite surface model underestimates the cross-polarized components due to the neglect of second-order Bragg scattering. The secondorder small perturbation method (SPM) can predict the depolarization in the plane of incidence, but the validity domain of SPM is restricted to small roughness [24].…”

Section: Introductionmentioning

confidence: 99%

Polarimetric Scattering from Two-Dimensional Dielectric Rough Sea Surface with a Ship-Induced Kelvin Wake

Guo

2016

International Journal of Antennas and Propagation

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Based on the polarimetric scattering model of second-order small-slope approximation (SSA-II) with tapered wave incidence for reducing the edge effect caused by limited surface size, monostatic and bistatic polarimetric scattering signatures of two-dimensional dielectric rough sea surface with a ship-induced Kelvin wake is investigated in detail by comparison with those of sea surface without ship wake. The emphasis of this paper is on an investigation of depolarized scattering and enhanced backscattering of sea surface with a ship wake that changes the sea surface geometric structure especially for low wind conditions. Numerical simulations show that in the plane of incidence rough sea surface scattering is dominated by copolarized scattering rather than cross-polarized scattering and that under low wind conditions a larger ship speed gives rise to stronger enhanced backscattering and enhanced depolarized scattering. For both monostatic and bistatic configuration, simulation results indicate that electromagnetic scattering signatures in the presence of a ship wake dramatically differ from those without ship wake, which may serve as a basis for the detection of ships in marine environment.

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Simulations of the bistatic scattering using two-scale model and the unified sea spectrum

Cited by 17 publications

References 11 publications

Sea Surface Monostatic and Bistatic EM Scattering Using SSA-1 and UAVSAR Data: Numerical Evaluation and Comparison Using Different Sea Spectra

Sea Surface Monostatic and Bistatic EM Scattering Using SSA-1 and UAVSAR Data: Numerical Evaluation and Comparison Using Different Sea Spectra

Angular Composite Facet Model with Shadowing Treatment for Backscattering from Two-Dimensional Rough Sea Surface

Polarimetric Scattering from Two-Dimensional Dielectric Rough Sea Surface with a Ship-Induced Kelvin Wake

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