Numerical simulations of scattering from time-varying, randomly rough surfaces

Toporkov, Jakov V.; Brown, Gerald R.

doi:10.1109/36.851961

Cited by 197 publications

(139 citation statements)

References 26 publications

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“…Two data sets as references are quoted here. One is the data set of Doppler simulations based on rigorous MOMI model by Toporkov and Brown [15], and the other is based on the TSM combined with the modulation transfer function (MTF) technique by Romeiser and Thompson [33], which has been demonstrated to be qualitatively consistent with the experimental results and other numerical approaches.…”

Section: Numerical Resultsmentioning

confidence: 87%

“…Rino et al [13] comparatively studied the backscattering and the Doppler spectra from one-dimensional (1-D) time-varying linear and nonlinear Creamer sea surfaces [14] for the first time. Toporkov and Brown [15] made a comprehensive study of the Creamer nonlinear surface scattering characteristics using the method of ordered multiple interactions (MOMI). Their results explicitly showed the higher Doppler shift and broadening of the Doppler spectra for nonlinear sea surfaces.…”

Section: Introductionmentioning

confidence: 99%

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Investigation on Doppler Spectral Characteristics of Electromagnetic Backscattered Echoes From Dynamic Nonlinear Surfaces of Finite-Depth Sea

Nie¹,

Min²,

Geng³

et al. 2012

PIER

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Abstract-The Doppler spectral characteristics of electromagnetic backscattered echoes from dynamic nonlinear surfaces of finite-depth sea is investigated with the second-order small-slope approximation (SSA-II). The revised nonlinear hydrodynamic choppy wave model (CWM) combining with an experiment-verified shoaling coefficient is utilized to model the finite-depth sea wave profiles, and the simulated surfaces of finite-depth sea show steeper crests and more flat troughs as depth decreases. First, Comparison of the Doppler spectra for linear sea surfaces and nonlinear choppy sea surfaces shows that nonlinear hydrodynamic effect greatly enhances the Doppler shift and the Doppler spectrum bandwidth, and the predicted results agree well with the rigorous numerical model data. The Doppler spectra of backscattered echoes from finite-depth sea with different depths are further evaluated. At small incident angles, the Doppler shifts and the spectra bandwidths are much lower for shallower sea, and the opposite situation can be gradually observed for increased incident angles. This indicates that the nonlinear wave-wave interactions among waves occur more frequently in finite-depth sea and the long waves will be suppressed while shorter wind waves will be boosted in shallower water. Moreover, the dependence of the Doppler spectral characteristics on polarization is also discussed.

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Section: Numerical Resultsmentioning

confidence: 87%

Section: Introductionmentioning

confidence: 99%

Investigation on Doppler Spectral Characteristics of Electromagnetic Backscattered Echoes From Dynamic Nonlinear Surfaces of Finite-Depth Sea

Nie¹,

Min²,

Geng³

et al. 2012

PIER

View full text Add to dashboard Cite

show abstract

“…How to choose this time interval is given in Ref. [20]. Repeat this EM scattering procedure for INT (T /τ ) times to get a time-varying field from this composite evolving model, then the Doppler spectrum can be obtained by using the standard spectralestimation technique,…”

Section: Doppler Spectrum Analysismentioning

confidence: 99%

“…Quasi-stationary algorithm [20,21] is used to obtain the time-evolving EM scattering field from the composite model. Then the Doppler spectra are analyzed by using a standard spectrum estimation technique.…”

Section: Introductionmentioning

confidence: 99%

Numerical Approach on Doppler Spectrum Analysis for Moving Targets Above a Time-Evolving Sea Surface

Qi¹,

Zhao

Nie³

2013

PIER

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Abstract-In order to analyze the Doppler spectrum of threedimensional (3-D) moving targets above a time-evolving sea surface, a hybrid method with acceleration techniques is proposed to simulate the electromagnetic (EM) scattering from the composite moving model. This hybrid iterative method combines Kirchhoff approximation (KA) and the multilevel fast multipole algorithm (MLFMA) to solve the EM backscattering from the rough sea surface and the targets, respectively, then mutual EM coupling effects between them are taken into account through an iterative process. To overcome the vast computational cost in the iterative process, acceleration approaches which can greatly reduce the calculation time are applied. Coupling area on the sea surface is truncated according to geometrical optic principle. Then a fast far-field approximation (FAFFA) is applied to speed up the mutual interactions between the targets and the sea surface. A successive iteration method is proposed to reduce the convergence steps for the MLFMA process. The accuracy and efficiency of this hybrid method with accelerations are demonstrated. Doppler spectra of backscattering signals obtained from such numerical EM simulations are compared for different incident angles, target velocities and surface models. The broadening effects of the Doppler spectra due to the mutual EM coupling interactions are studied.

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“…The relationship of the spectral width with breaking waves is discussed in Section 4. For the time-varying composite scattering model, the Doppler spectrum is calculated with a standard spectral estimation technique [39] …”

Section: Doppler Spectrummentioning

confidence: 99%

Investigation of Low-Grazing-Angle Microwave Backscattering From Threedimensional Breaking Sea Waves

Luo¹,

Zhang²,

Wang³

et al. 2011

PIER

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Abstract-The microwave backscattering of the sea surface is investigated with the wedge-shaped breaking waves for the super events at low grazing angles (LGA). According to the relationship between the wave breaking and the whitecap, the finite three-dimensional wedges are utilized to approximately model the breaking waves, of which the spatial distribution is simulated with whitecap coverage. The phasemodified two-scale method (TSM) and method of equivalent currents (MEC) are used to calculate the surface and volume scattering of sea surface and breaking waves respectively. The sea spikes in LGA are observed by this model, and the strong directionality is caused by the breakers. Considering the Bragg phase velocity, orbital motion of facets and wind drift, the Doppler spectrum is simulated with the time series of sea clutter. Included the breaking waves, the scattering model indicates that the enhanced non-Bragg scattering leads to the extended Doppler spectrum width. The numerical results agree with the measured data well at LGA. Compared with the statistical models, the complex physical mechanism of the sea scattering is explicitly described in this paper.

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Numerical simulations of scattering from time-varying, randomly rough surfaces

Cited by 197 publications

References 26 publications

Investigation on Doppler Spectral Characteristics of Electromagnetic Backscattered Echoes From Dynamic Nonlinear Surfaces of Finite-Depth Sea

Investigation on Doppler Spectral Characteristics of Electromagnetic Backscattered Echoes From Dynamic Nonlinear Surfaces of Finite-Depth Sea

Numerical Approach on Doppler Spectrum Analysis for Moving Targets Above a Time-Evolving Sea Surface

Investigation of Low-Grazing-Angle Microwave Backscattering From Threedimensional Breaking Sea Waves

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