Studies of dual polarized low grazing angle radar sea scatter in nearshore regions

Trizna, D.B.; Carlson, David J.

doi:10.1109/36.499754

Cited by 85 publications

(38 citation statements)

References 13 publications

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“…In that range of grazing angle values, s VVrel 0 can be modeled by a power behavior in a n with n = 3.15 (sd = 0.42) whereas from (3) n = 3.14. We verified that the theoretical value of n was negligibly modified by taking into account the slight damping of ψ(k B ) as a decreases resulting, for a shape of ψ in k À4 , in a variation of f VV in tan 4 a instead of sin 4 a in (3) [Trizna, 1996]. Furthermore, no significant variation of n with wind direction was detected, which reflects the observed insensitivity of the backscattered power to wind (section 5.1).…”

Section: Variation Of the Relative Vertically Polarized Backscatterinmentioning

confidence: 52%

Observations of the sea surface by coherent L band radar at low grazing angles in a nearshore environment

Forget¹,

Saillard²,

Broche³

2006

J. Geophys. Res.

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[1] Coherent microwave L band signals have been collected in a Mediterranean coastal zone in horizontal transmit/horizontal receive (HH) and vertical transmit/vertical receive (VV) polarization modes at low grazing angles and under light to strong wind conditions. Doppler spectra have distinct morphologies depending on polarization mode and wind conditions. VV spectra and, only under light wind conditions, HH spectra present features that are consistent with an interaction process of Bragg type between electromagnetic waves and the sea surface, including the Doppler effects imparted by surface currents. At high wind, fast scatterers associated with greater velocities than Bragg velocity can be detected on HH spectra, depending on the direction of propagation of long waves and not on wind direction, these directions being not necessarily the same in the coastal zone considered. For a given radar range the backscattered power in VV was found to be almost constant, which suggests saturation of the wave spectrum in the short-wave range and isotropy of the short-wave spectral energy in the downwind half plane. For vertical polarization the observed variations of the relative backscattering coefficient with grazing angle are supported by the slightly rough surface scattering theory, but the HH/VV polarization ratio is much greater than predicted by this theory. The data suggest that at low grazing angles, non-Bragg scattering effects play a major role at horizontal polarization, especially in high-wind-high-wave conditions. Citation: Forget, P., M. Saillard, and P. Broche (2006), Observations of the sea surface by coherent L band radar at low grazing angles in a nearshore environment,

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Section: Variation Of the Relative Vertically Polarized Backscatterinmentioning

confidence: 52%

Observations of the sea surface by coherent L band radar at low grazing angles in a nearshore environment

Forget¹,

Saillard²,

Broche³

2006

J. Geophys. Res.

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“…Finally, we do not suppose that the model presented here can explain microwave backscatter completely at incidence angles well above 80 ø . For instance, much evidence has recently accumulated that HH cross sections can occasionally exceed VV cross sections at very high incidence angles [Trizna et al, 1991;Lee et al, 1996;Smith et al, 1996]. Such effects cannot be explained by the present model and probably require multiple scattering and Brewster's angles' effects for their complete explanation [Trizna and Carlson, 1996].…”

Section: Modeling Doppler Effectsmentioning

confidence: 98%

A model for microwave Doppler sea return at high incidence angles: Bragg scattering from bound, tilted waves

Plant¹

1997

J. Geophys. Res.

134

112

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this first moment by surface waves tens of meters in length is the same for the two polarizations at low to moderate incidence angles and can be interpreted in terms of the advection of free centimetric waves by the long waves. At higher incidence angles, however, this modulation is different for the two polarizations and cannot be explained by simple advection of free waves. Finally, microwave cross sections measured at high incidence angles using horizontal polarization are much larger than can be explained by a composite surface theory that includes only freely propagating centimetric waves. Most of these effects can be explained by the composite surface model presented here, which includes Bragg scattering from both free and bound, tilted waves.

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“…Due to the dependence of the radar cross section (RCS) on wind speed [15] and the angle between the radar look direction and the wind direction [16], X-band marine radar has been exploited to retrieve wind parameters [12]. Wind direction has generally been determined based on the fact that the backscatter of an HH-polarized X-band radar operating at grazing incidence presents only one peak in the upwind direction [39].…”

Section: Wind Measurementsmentioning

confidence: 99%

Ocean Wind and Wave Measurements Using X-Band Marine Radar: A Comprehensive Review

2017

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Ocean wind and wave parameters can be measured by in-situ sensors such as anemometers and buoys. Since the 1980s, X-band marine radar has evolved as one of the remote sensing instruments for such purposes since its sea surface images contain considerable wind and wave information. The maturity and accuracy of X-band marine radar wind and wave measurements have already enabled relevant commercial products to be used in real-world applications. The goal of this paper is to provide a comprehensive review of the state of the art algorithms for ocean wind and wave information extraction from X-band marine radar data. Wind measurements are mainly based on the dependence of radar image intensities on wind direction and speed. Wave parameters can be obtained from radar-derived wave spectra or radar image textures for non-coherent radar and from surface radial velocity for coherent radar. In this review, the principles of the methodologies are described, the performances are compared, and the pros and cons are discussed. Specifically, recent developments for wind and wave measurements are highlighted. These include the mitigation of rain effects on wind measurements and wave height estimation without external calibrations. Finally, remaining challenges and future trends are discussed.

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Studies of dual polarized low grazing angle radar sea scatter in nearshore regions

Cited by 85 publications

References 13 publications

Observations of the sea surface by coherent L band radar at low grazing angles in a nearshore environment

Observations of the sea surface by coherent L band radar at low grazing angles in a nearshore environment

A model for microwave Doppler sea return at high incidence angles: Bragg scattering from bound, tilted waves

Ocean Wind and Wave Measurements Using X-Band Marine Radar: A Comprehensive Review

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