Sun glitter radiance and radar cross‐section modulations of the sea bed

Hennings, Ingo; Matthews, Janice R.; Metzner, M.

doi:10.1029/93jc02777

Cited by 46 publications

(43 citation statements)

References 18 publications

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“…Variations in the sea surface roughness due to submarine topography can result in modulation of the radiance intensity in optical imageries and, as a result, submarine topographic features are frequently observed in optical satellite imageries since the launch of SKYLAB [Hennings et al, 1988[Hennings et al, , 1994Gagliardini and Colón, 2004;Matthews et al, 2008].…”

Section: Introductionmentioning

confidence: 99%

“…[5] The relaxation rate (or wave growth rate) m r is one of the most important parameters in imaging models of sea bottom topography for both space-borne radar [Alpers and Hennings, 1984;Zimmerman, 1985;Vogelzang et al, 1997] and Sun glitter [Hennings et al, 1994]. The magnitude of water depth variations retrieved from SAR or Sun glitter imagery depends critically on making a correct choice for m r .…”

Section: Introductionmentioning

confidence: 99%

“…[4] Comparative studies [Hennings et al, 1988[Hennings et al, , 1994Gagliardini and Colón, 2004] between SAR and optical imageries show that each type of sensor has its own advantages and limitations when used to observe sea bottom features according to the way in which each detects sea surface roughness. Optical sensors are limited by the needs for cloud-free conditions, daylight, high solar azimuth and zenith angle months (e.g., from April to September in the Northern Hemisphere), while SAR sensors are capable of observing the sea surface under all-weather conditions throughout the year.…”

Section: Introductionmentioning

confidence: 99%

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Sun glitter imaging of submarine sand waves on the Taiwan Banks: Determination of the relaxation rate of short waves

Shao¹,

Li²,

Li³

2011

J. Geophys. Res.

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[1] Above sand waves on the seafloor, surface short waves, which are responsible for the radiance distribution in remote sensing imagery, are modulated gradually by the submarine topography. The relaxation rate m r characterizes the rate at which the short waves reach their saturation range after being disturbed. It is a key parameter in the weak hydrodynamic interaction theory and is also a most important parameter in the imaging mechanism used for mapping submarine bottom topography. In this study, a robust expression containing intensity and phase (advection effect) modulations of the perturbed action spectrum of short waves was deduced, by using the first-order weak hydrodynamic interaction theory. On the basis of the phase modulation, a method was developed to determine the relaxation rate in the Sun glitter imaging mechanism. The relaxation rates were estimated using in situ data measured on a cruise over the sand waves of the Taiwan Banks, a sea area between the East China Sea and the South China Sea, on 28-29 August 2006. Results showed that, under a wind speed of 5.0 m s −1 , the relaxation rate of short waves was about 0.055 s −1 in response to current variations and about 0.025 s −1 equivalently in response to sea bottom topographic variations. The former value could be applied to interpret the amplitude of submarine topography by using satellite imagery, while the latter one (equivalent relaxation rate m′ r ) could help to more accurately calibrate the spatial position of the retrieved sea bottom topography.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Sun glitter imaging of submarine sand waves on the Taiwan Banks: Determination of the relaxation rate of short waves

Shao¹,

Li²,

Li³

2011

J. Geophys. Res.

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“…According to the sun glitter geometry model, it has been found that the signature of sun glitter images depends strongly on the viewing angle. 19,23,24 He et al 25 discussed the brightness reversal of the Taiwan Banks submarine sand waves in sun glitter images from charge-coupled diodes onboard the HJ-1B satellite. Therefore, multiangle sun glitter images can present useful additional information compared with single angle images.…”

Section: Introductionmentioning

confidence: 99%

“…The Cox-Munk model established a fundamental theory enabling sun glitter images to detect marine dynamic processes, and sun glitter remote sensing has played an important role in a wide range of oceanographic studies, including internal wave detection, 15,16 oil slick detection, 17 and shallow underwater topography mapping. 7,18 Hennings et al 19 developed a key theory of the sun glitter imaging mechanisms for underwater bottom topography based on the Cox-Munk model and SAR imaging mechanisms. He et al, 20 Shao et al, 21 and Zhang et al 22 used sun glitter imagery to observe sand waves in the Taiwan Banks, and statistically analyzed their distributions and characteristics.…”

Section: Introductionmentioning

confidence: 99%

Bathymetric mapping of submarine sand waves using multiangle sun glitter imagery: a case of the Taiwan Banks with ASTER stereo imagery

Zhang

Yang

Lou

et al. 2015

J. Appl. Remote Sens

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Abstract. Submarine sand waves are visible in optical sun glitter remote sensing images and multiangle observations can provide valuable information. We present a method for bathymetric mapping of submarine sand waves using multiangle sun glitter information from Advanced Spaceborne Thermal Emission and Reflection Radiometer stereo imagery. Based on a multiangle image geometry model and a sun glitter radiance transfer model, sea surface roughness is derived using multiangle sun glitter images. These results are then used for water depth inversions based on the Alpers-Hennings model, supported by a few true depth data points (sounding data). Case study results show that the inversion and true depths match well, with high-correlation coefficients and root-mean-square errors from 1.45 to 2.46 m, and relative errors from 5.48% to 8.12%. The proposed method has some advantages over previous methods in that it requires fewer true depth data points, it does not require environmental parameters or knowledge of sand-wave morphology, and it is relatively simple to operate. On this basis, we conclude that this method is effective in mapping submarine sand waves and we anticipate that it will also be applicable to other similar topography types. © The Authors. Published by SPIE under a Creative Commons Attribution 3.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.

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Whitecap features induced by submarine sand waves in stereo optical imagery

Zhang

Lou

et al. 2015

JGR Oceans

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Under high wind speed conditions, waves break on the sea surface producing whitecaps, which can be recorded in optical satellite images. However, the breaking of waves is also influenced by submarine topography. In this study, we investigate the whitecap features induced by submarine sand waves using optical stereo images. We determine the whitecap coverage in images, and estimate the probabilities of wave breaking. The observed and estimated results are in agreement with some previous investigation results. A physical model is used to discuss the mechanisms of wave breaking along sand wave crests. The physical model is able to qualitatively explain the differences between the observed whitecap coverage and the estimated probability of wave breaking between the sand wave area (SWA) and the background area (BGA). Further analysis shows that the periodic sand wave system may play the role of a frequency‐control device, and may result in more broken waves in the SWA than in the BGA. This study demonstrates that it is possible to observe submarine topography under high‐wind conditions by using whitecap features.

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Sun glitter radiance and radar cross‐section modulations of the sea bed

Cited by 46 publications

References 18 publications

Sun glitter imaging of submarine sand waves on the Taiwan Banks: Determination of the relaxation rate of short waves

Sun glitter imaging of submarine sand waves on the Taiwan Banks: Determination of the relaxation rate of short waves

Bathymetric mapping of submarine sand waves using multiangle sun glitter imagery: a case of the Taiwan Banks with ASTER stereo imagery

Whitecap features induced by submarine sand waves in stereo optical imagery

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