Investigation on the Scattering From One-Dimensional Nonlinear Fractal Sea Surface by Second-Order Small-Slope Approximation

Luo, Gen; Min, Zhang

doi:10.2528/pier12082706

Cited by 10 publications

(6 citation statements)

References 41 publications

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“…[1][2][3] This study faces two problems: modeling the oceanic surfaces and establishing the scattering model. The reasonable description of the oceanic surfaces is the necessary prerequisite to the simulation of Doppler spectra.…”

Section: Introductionmentioning

confidence: 99%

Study on Doppler spectra of two-dimensional skewed sea surfaces

Chen

Min

Zhao

et al. 2014

Waves in Random and Complex Media

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This paper deals with the effects of horizontal skewness on Doppler spectra. A.K. Fung et al. pointed out that the crests of the sea waves are tilted towards the wind direction, which is referred to as horizontal skewness. Although the nonlinear sea surface is more realistic than the linear one, it cannot embody the statistical front-back asymmetry of real sea waves due to the influence of the wind. Thus, the impact of horizontal skewness must be considered. The first-order modified Lagrange model for asymmetric ocean waves is combined with Monte Carlo method to produce the two-dimensional (2-D) time-varying skewed sea surfaces which are nonlinear and skewed simultaneously. Moreover, the second-order small-slope approximation method is used to calculate the scattering field and study the Doppler spectral characteristics from skewed sea surfaces. Horizontal skewness makes Doppler spectra broader in upwind case, but narrower in downwind case. In addition, the impact of horizontal skewness on Doppler spectra is dependent on wind direction and incident elevation angle.

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Section: Introductionmentioning

confidence: 99%

Study on Doppler spectra of two-dimensional skewed sea surfaces

Chen

Min

Zhao

et al. 2014

Waves in Random and Complex Media

Self Cite

View full text Add to dashboard Cite

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“…The study of the electromagnetic scattering mechanism from the sea surface is of great significance in remote sensing systems and target recognition with complex background [1]. The research on the electromagnetic scattering model of the sea surface can not only help to estimate and optimize the target recognition algorithm, but also be used to supplement experimental data [2][3][4]. The high-resolution radar characteristics of the sea surface under high wind conditions at low grazing angles (LGA) have been a point of discussions and in-depth analysis in recent years [5][6][7][8].…”

Section: Introductionmentioning

confidence: 99%

A Volume-Surface Composite Scattering Model for Nonlinear Ocean Surface With Breaking Waves and Foam Layers Under High Wind Conditions

Zhang¹,

Su²,

Wu³

2019

PIER B

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Electromagnetic scattering from the sea surface is of great significance in ocean remote sensing especially under high wind conditions. A novel volume-surface composite scattering model of nonlinear rough sea surfaces with breaking waves and foam layers under high wind conditions is presented in this study. Based on the semi-deterministic facet scattering model (SDFSM), using a ray tracing method combined with impedance equivalent edge currents (RT-IEEC) and vector radiative transfer theory (VRT), the backscattering characteristics of the sea surface with breaking waves and foam layers are investigated. The crest-and static-foam coverage was introduced to determine the breaking point and foam coverage distribution. The dependence of the backscattering coefficient of the sea surface with and without breaking waves and foam layers on the incident angle, wind speed, and the polarization are discussed in detail. The results of numerical simulations are analyzed and compared with the measured data from the relevant references which verifies the validity of our volume-surface composite scattering model. The synthetic aperture radar (SAR) image simulations of the surface with and without the breaking waves and foam layers are compared, and the combined effects of the breaking waves and whitecaps are analyzed.

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“…To overcome the drawbacks of linear sea surface model, several nonlinear hydrodynamic models have been proposed, such as Creamer model [19] as well as its simplified version (Creamer model at second-order) [12], choppy wave model (CWM) [20] as well as its improved version (C2WM) [18], West model [21], narrow-band Lagrange model [22], and nonlinear fractal sea surface model [23]. These models have been extensively utilized to better predict Doppler spectra of sea echoes for both 1-D [13,17,18,[22][23][24][25] and 2-D sea surfaces [12,[26][27][28][29] with analytical models or numerical algorithms, in particular for low-grazing case. Not surprisingly, the Doppler spectra obtained by nonlinear sea surface models are more consistent with measurements in comparison with linear sea surface model.…”

Section: Introductionmentioning

confidence: 99%

Doppler Spectrum of Scattered Wave From Two-Dimensional Time-Varying Nonlinear Sea Surfaces Under Right-Hand Circularly Polarized Wave Incidence

Wu¹,

Ren²,

Zhang³

2019

PIER B

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Electromagnetic scattering from time-varying sea surfaces under right-hand circularly polarized (RHCP) wave incidence is investigated, with emphasis on exploring the influence of nonlinear hydrodynamic interactions on Doppler spectral signatures as well as on examining the polarization difference of Doppler spectra between right-hand and left-hand polarized scattering waves. The choppy wave model (CWM) is adopted for describing nonlinear hydrodynamic interactions between ocean waves, and it is constructed by adding horizontal displacements through performing Hilbert transform for a reference linear surface model. Simulation results show that Doppler spectral signatures are significantly influenced by nonlinear hydrodynamic interactions in particular in low-grazing angle regime. It is also indicated that Doppler spectral signatures show distinct polarization dependence. In addition, numerical simulations show that Doppler shift of left-hand polarized scattering wave increases obviously with wind speed increasing, whereas the Doppler shift of right-hand polarized scattering wave looks less sensitive to wind speed variations. The result is potentially valuable in remote sensing applications with Global Navigation Satellite System-Reflectometry (GNSS-R) signals.

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Investigation on the Scattering From One-Dimensional Nonlinear Fractal Sea Surface by Second-Order Small-Slope Approximation

Cited by 10 publications

References 41 publications

Study on Doppler spectra of two-dimensional skewed sea surfaces

Study on Doppler spectra of two-dimensional skewed sea surfaces

A Volume-Surface Composite Scattering Model for Nonlinear Ocean Surface With Breaking Waves and Foam Layers Under High Wind Conditions

Doppler Spectrum of Scattered Wave From Two-Dimensional Time-Varying Nonlinear Sea Surfaces Under Right-Hand Circularly Polarized Wave Incidence

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