Low-grazing-angle (LGA) sea-spike backscattering from plunging breaker crests

West, James C.

doi:10.1109/36.992830

Cited by 34 publications

(19 citation statements)

References 8 publications

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“…Near the Brewster angle of the sea surface, the multipath of V V is greatly attenuated; leading to HH cross-sections are greater than V V . West introduced another model in [7]. The back reflections from the specular points on the forming jet and within the cavity under the jet can simultaneously add destructively at V V and constructively at horizontal, leading to HH exceeds V V .…”

Section: Introductionmentioning

confidence: 99%

Electromagnetic Scattering and Doppler Analysis of Three-Dimensional Breaking Wave Crests at Low-Grazing Angles

Qi¹,

Zhao²,

Yang³

et al. 2011

PIER

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Abstract-The electromagnetic scattering of the synthesized threedimensional (3-D) breaking wave crests which are formed by azimuthally aligning the individual 2-D breaking wave profiles has been numerically studied at the low-grazing angles (LGA) by using the multilevel fast multipole algorithm (MLFMA) with adaptive higher order hierarchical Legendre basis functions. Different from the specular (or quasi-specular) reflection and Bragg scattering, the "sea-spike" phenomenon which is characterized by that horizontally polarization (HH) signals greatly exceed vertically polarization (V V ) signals has been demonstrated by analyzing both the backscattering of 3-D LONGTANK series and a plunging breaker. For the timedependent evolution of the plunging breaker, the Doppler shifts and Doppler splitting effects are investigated by applying the fast Fourier transform (FFT) with a moving Hamming window. The spectrum of HH scattering has the feature of concentration, while the spectrum of V V scattering shows the Doppler splitting effects.

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Section: Introductionmentioning

confidence: 99%

Electromagnetic Scattering and Doppler Analysis of Three-Dimensional Breaking Wave Crests at Low-Grazing Angles

Qi¹,

Zhao²,

Yang³

et al. 2011

PIER

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“…Nevertheless an analysis of all our data, obtained for several grazing angles between 6°and 25°, reveals the absence of any significant influence of the grazing angle on the Doppler spectra. Multipath reflections from the front face of the breaking wave were not modeled in the works of Ja et al [2001] and West [2002].…”

Section: Discussionmentioning

confidence: 99%

Laboratory study of the fine structure of short surface waves due to breaking: Two‐directional wave propagation

Rozenberg

Ritter

2005

J. Geophys. Res.

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[1] This study was stimulated by the need to identify the influence of breaking on the evolution of the short surface wave field responsible for microwave scattering. Laboratory measurements of the fine space-time structure of short gravity-capillary waves and Ku band scattering at grazing and moderate incidence from spilling and plunging breaking waves in a laboratory wave channel are presented. Unsteady breaking waves are generated by focusing wave groups in space-time domains. A scanning laser slope gauge was used for measuring capillary-gravity waves with wavelengths of 2 mm to 10 cm and frequency ranges of up to 150 Hz. A dual polarized (VV, HH) coherent pulsed Ku band scatterometer with a 3 ns temporal resolution was used to simultaneously obtain Doppler spectra of the scattered signals from the breaking area for grazing angles from 6°to 25°. Two-dimensional filtering in the wave number-frequency plane as well as plus/minus Doppler spectra were used to separate the direction of propagation of the surface waves within the breaking region. It was found that the breaking splash is the main source of the surface wave generation. The short surface wave slope field produced by breaking could be separated into short (4-8 mm wavelength), fast waves and free gravity-capillary waves. Both types of waves were found to be co-and counterpropagate relative to the dominant wave propagation direction. The Doppler spectrograms reveal the presence of high-frequency waves at the moment of breaking that can be associated with short, fast waves. The low-frequency part of the Doppler spectrogram is consistent with the appearance of free waves.Citation: Rozenberg, A., and M. Ritter (2005), Laboratory study of the fine structure of short surface waves due to breaking: Twodirectional wave propagation,

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“…Holliday et al [1] applied forward-backward method (FBM) for calculating scattering from dielectric sea, and showed that highly accurate results at X-band (10 GHz) were obtained for the case of a steepened sea wave. A hybrid method combining the method of moments (MoM) and geometrical theory of diffraction (GTD) was used in [2] to investigate the scattering from breaking water wave crests. Recently, a multilevel fast multipole algorithm (MLFMA) was applied in [3,4] to study the microwave backscattering from three-dimensional (3D) breaker wave crests at low grazing angle illumination.…”

Section: Introductionmentioning

confidence: 99%

Scattering From a Target Above Rough Sea Surface With Breaking Water Wave by an Iterative Analytic-Numerical Method

Xu¹,

Guo²,

Wang³

et al. 2015

PIER M

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Abstract-Two-dimensional (2D) electromagnetic scattering from a target above the sea with breaking water wave is studied by a multiregional iterative analytical-numerical method that combines the boundary integral method (BIM) and the Kirchhoff approximation (KA). Based on the "PiersonMoskowitz" (PM) sea surface and the LONGTANK breaking wave, a theoretical model of a target above the rough sea surface with breaking wave is built firstly in this paper. Unlike traditional sea surface, the multipath scattering between the crest of the breaking wave and the target cannot be accurately predicted based on KA alone. To improve the algorithm precision, a multiregional hybrid analytical-numerical method is proposed. In our multiregional model, the whole sea is divided into two subregions: the breaking wave and the PM sea surface. The scattering from the breaking wave and the object is well approximated by BIM, while the PM sea surfaces can be estimated very well by KA based on Fresnel theories. Taking the interaction between KA region and BIM region into account, an iterative system is developed which gives a quick convergence. The hybrid technique presented here is highly efficient in terms of computing memory, time consumed, and versatility.

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Low-grazing-angle (LGA) sea-spike backscattering from plunging breaker crests

Cited by 34 publications

References 8 publications

Electromagnetic Scattering and Doppler Analysis of Three-Dimensional Breaking Wave Crests at Low-Grazing Angles

Electromagnetic Scattering and Doppler Analysis of Three-Dimensional Breaking Wave Crests at Low-Grazing Angles

Laboratory study of the fine structure of short surface waves due to breaking: Two‐directional wave propagation

Scattering From a Target Above Rough Sea Surface With Breaking Water Wave by an Iterative Analytic-Numerical Method

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