A semi-empirical sea-spectrum model for scattering coefficient estimation

Fung, A.K.; Lee, Khim

doi:10.1109/joe.1982.1145535

Cited by 196 publications

(112 citation statements)

References 15 publications

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“…This involved physics is usually described (at least as long as remote sensing applications are concerned) by means of a sea surface energy spectrum [2], [21], [22], and of the following classical dispersion relation [2] An exhaustive discussion on problems involved in the whole ocean spectrum definition, use, and meaning is beyond the aim of this paper and can be found in the specialized literature [14]- [17]. We emphasize, hereafter, only shape and signatures of some common spectra and their relevance to electromagnetic studies and SAR image formation, as detailed in the Section III.…”

Section: Concepts Of Ocean Modelingmentioning

confidence: 99%

SAR raw signal simulation of oil slicks in ocean environments

Franceschetti¹,

Iodice²,

Riccio³

et al. 2002

IEEE Trans. Geosci. Remote Sensing

105

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Abstract-Synthetic aperture radar (SAR) raw signal simulation is a powerful tool for design of oil slick detection and interpretation systems. In this paper, the ocean simulation issues are presented, and the main problems relating to the oil presence on the sea surface are treated. Attention is focused on the electromagnetic side of the problem, with care to the sensor signatures, the dielectric, physical-chemical, and geometric nature of the oil slick, and to the environmental conditions. The presented SAR simulator is based on an ocean model and an oil slick model. The former makes use of multiscale description of the ocean surface: the distributed surface model for the SAR-ocean interaction is considered by taking into account the nonlinear hydrodynamic effect for the water particle movement. The latter model implements a modification of the ocean spectrum, based on the Marangoni theory and accounting for the nonlinear wave interaction mechanism. However, the proposed SAR raw signal simulator is modular and flexible, thus allowing other possible physical models for modeling the oil slick effect over the ocean spectrum. Meaningful SAR simulation experiments are presented and discussed, elucidating the role of difference on pollutants, oil thickness, wind speed and direction, incident wavelength and angle and other radar parameters. Validation of the simulator is also presented by comparison with experimental data. A striking conclusion of the paper is that higher order moments (from the second on) of oil slick SAR image statistics are quite different compared to those pertinent to an equivalent wind speed decrease on the imaged area. This suggests a convenient way to define new appropriate oil slick signatures.

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Section: Concepts Of Ocean Modelingmentioning

confidence: 99%

SAR raw signal simulation of oil slicks in ocean environments

Franceschetti¹,

Iodice²,

Riccio³

et al. 2002

IEEE Trans. Geosci. Remote Sensing

105

View full text Add to dashboard Cite

show abstract

“…In the high frequency bands, the TSM [34] is used for the calculation of sea surface scattering, which reckons that the waves contributing to the Bragg process are locally tilted by large-scale waves [35]. The two scale scattering coefficient is simply a weighted average of the local small perturbations coefficients, the weight being proportional to the probability of the slope's probability distribution.…”

Section: Phase-modified Two-scale Methodsmentioning

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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“…k is the spatial wavenumber vector, which is equivalent to (k x , k y ) and (k, ϕ). P ( k) is the sea spectrum, which is chosen as Pierson-Moskowitz (PM) [24]. For gravity waves, ω satisfies the dispersion relation ω 2 = gk and g is the gravity acceleration constant.…”

Section: Linear Sea Surface Modelmentioning

confidence: 99%

Scattering Analysis for Ship Kelvin Wakes on Two-Dimensional Linear and Nonlinear Sea Surfaces

Sun¹,

Min

Wang³

et al. 2013

PIER B

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Abstract-The ship Kelvin-wake models on two-dimensional (2-D) linear and nonlinear sea surfaces are combined with the second-order small-slope approximation method (SSA-II) to comparatively study the corresponding electromagnetic (EM) scattering characteristics. The nonlinear sea-surface models include the Choppy Wave Model (CWM) and the second-order Creamer model (Creamer (2)). Considering the limitations of using the ideal plane EM wave incident upon a rough sea surface of the limited size, the modified tapered wave is utilized as the incident wave to derive the scattering waves. Due to the fact that the nonlinear effects of Creamer (2) surfaces is obviously stronger than those of CWM surfaces, the bistatic normalized radar cross section (NRCS) calculated from Creamer (2) surfaces is significantly greater than that of its linear and CWM surfaces for scattering angles departing from the specular direction, and the backscattering coefficients from Creamer (2) surfaces are also the greatest except within quasi-specular (near vertical incidence) region. Moreover, for the linear and nonlinear sea surfaces, the influences of different wind speeds and directions on scattering characteristics are also calculated and analyzed in detail. However, taking the ship Kelvin wakes into account, the corresponding scattering features are obviously distinct from those of the single linear and nonlinear sea surfaces. This helps to provide a basis to extract the related ship information through the scattering characteristics of ship Kelvin wakes. Also it shows that the small-slope approximation method is a very effective analysis method to deal with the EM scattering from the rough sea surface.

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A semi-empirical sea-spectrum model for scattering coefficient estimation

Cited by 196 publications

References 15 publications

SAR raw signal simulation of oil slicks in ocean environments

SAR raw signal simulation of oil slicks in ocean environments

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

Scattering Analysis for Ship Kelvin Wakes on Two-Dimensional Linear and Nonlinear Sea Surfaces

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