Interpreting sea surface slicks on the basis of the normalized radar cross‐section model using RADARSAT‐2 copolarization dual‐channel SAR images

Ivonin, Dmitry V.; Skrunes, Stine; Brekke, Camilla; Ivanov, A. Yu.

doi:10.1002/2016gl068282

Cited by 20 publications

(23 citation statements)

References 31 publications

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“…In contrast to [16], however, [8] reported significant suppression of the NP radar backscatter in the presence of surface films. Recently, [18] suggested a August 7, 2016 DRAFT new algorithm for discrimination of oil spills and look-alikes in dual co-polarized SAR measurements, using the observed effect of surface films on suppression of both Bragg waves and wave breaking.…”

mentioning

confidence: 99%

Wave Breaking in Slicks: Impacts on C-Band Quad-Polarized SAR Measurements

Hansen¹,

Kudryavtsev

Chapron

et al. 2016

IEEE J. Sel. Top. Appl. Earth Observations Remote Sensing

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Radarsat-2 C-band quad-polarization SAR observations of crude oil, emulsion, and plant oil slicks acquired in the wind speed range from 4 to 8 m/s and incidence angles from 30 degrees to 50 degrees are analyzed to yield new insights into the attenuation of short waves and breaking waves by surface slicks in real conditions. To provide a direct quantitative assessment of the surface wave damping, the measurements are decomposed into polarization difference (PD), polarization ratio (PR), nonpolarized (NP), and cross-polarized (CP) components. The PD signals relate to the extent of Bragg damping in the slick areas, over which the PR is systematically higher than over the ambient sea surface. Attenuation of the breaking waves is revealed to affect both the CP and the NP signals, with distinct but weaker contrasts compared to that of the PD. A revised physical model description is proposed to provide consistent interpretation of the polarized and NP signals. The results suggest that the different slick types and look-alikes can be efficiently discriminated and classified.

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mentioning

confidence: 99%

Wave Breaking in Slicks: Impacts on C-Band Quad-Polarized SAR Measurements

Hansen¹,

Kudryavtsev

Chapron

et al. 2016

IEEE J. Sel. Top. Appl. Earth Observations Remote Sensing

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“…Two RS and two TS images were co-located in time and space. Two RS images (RSb and RSd) with an SNR within the slicks for the HH channel (SNR slick ) of more than 5 dB were used in work [35]. We used the HH channel of an image for the SNR slick calculation, since the HH channel has lower NRCS than the VV channel.…”

Section: Experimental Oil Spill Exercises and Oil Thickness Assessmentmentioning

confidence: 99%

“…is the relative change in the intensity of the Bragg ripples in the oil slick [35]. Thus, from Equations (7)-(9) for the radio thin slicks (see Appendix B), the RND parameter should be sensitive mainly to the information about the slick type (the film elasticity E f ):…”

Section: Step 3: Elimination Of the Unknown Oil Thickness Variationsmentioning

confidence: 99%

“…on the incidence angle and various parameters describing the weather conditions [26,34]. Using these known coefficients, the polarization parameter, called resonant to non-resonant signal damping (RND) was proposed by Ivonin et al [35]. By definition, the RND is assumed to be highly sensitive to the type of oil slick (its elasticity, for example) and has a low dependence on SAR observation properties (incidence angle, frequency band, etc.…”

Section: Introductionmentioning

confidence: 99%

“…The main goal of this study is to formulate a practically significant generalization of RS and TS data for a certain range of weather conditions, incidence angles, and signal-to-noise ratio (SNR) conditions, including low SNR that can be implemented in the form of a C-and X-band mineral oil diagram, which could be used for operational tasks including monitoring environmentally hazardous spills. Only data with a good SNR in the range of 5 to 12 dB within the slick were used in previous works [35,36] to ensure the noise did not affect the results. In this study, we analyze an extended dataset with an SNR within the slick descending to −3 dB, which means that the useful signal is three times weaker than the NESZ.…”

Section: Introductionmentioning

confidence: 99%

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Mineral Oil Slicks Identification Using Dual Co-polarized Radarsat-2 and TerraSAR-X SAR Imagery

et al. 2020

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This study is devoted to a generalization of C-band Radarsat-2 and X-band TerraSAR-X synthetic aperture radar (SAR) data in the form of a diagram serving to easily identify mineral oil slicks (crude oil and emulsions) and separate them from the other oil slicks. The diagram is based on the multi-polarization parameter called Resonant to Non-resonant signal Damping (RND) introduced by Ivonin et al. in 2016, which is related to the ratio between damping within the slick of the short waves and wave breakings. SAR images acquired in the North Sea during oil-on-water exercises in 2011–2012 containing three types of oil spills (crude oil, emulsion, and plant oil) were used. The analysis was performed under moderate sea conditions (wind speeds of 2–6 m/s and sea wave heights of less than 2 m), the incidence angles of 27°–49°, and the signal-to-noise ratio (SNR) of −3 to 11 dB within slicks. On the diagram plane, created by the RND parameter and the Bragg wave number, the mineral oil samples form a well-outlined zone, called a mineral oil zone. For C-band data, the plant oil samples were clearly distinguished from the mineral oils in the diagram. Determination of the confidence level for the detection of mineral oils versus plant oil was proposed using the mineral oil zone boundaries. The mineral oil data with SNR within slicks better than 2 dB lay within this zone with a confidence level better than 65%. The plant oil data with the same SNR lay outside this zone with a confidence level of better than 80%. For mineral oil with SNR of −3 dB, the confidence level is 55%.

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Experimental research on oil film thickness and its microwave scattering during emulsification

Guo

Liu

et al. 2021

J. Ocean. Limnol.

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Synthetic Aperture Radar (SAR) plays a major role in identifying oil spills on the sea surface. However, obtaining information of oil spill thickness (volume) is still a challenge. Emulsifi cation is an important process aff ecting the thickness and normalized radar cross section (NRCS) of oil fi lm. Experiments of crude oil emulsifi cation with C-band fully-polarized scatterometer were conducted combining airborne hyperspectral imaging spectrometer and 3D laser scanner observation data, to provide experimental parameters and method to support accurate remote sensing monitoring on marine oil spill. It is further proved that through quantitative homogeneous emulsifi ed oil spill experiments, to a certain extent, the NRCS of oil fi lm increased during the emulsifi cation process of crude oil. The backscattering mechanism of crude oil emulsifi cation was explored using a semi-empirical model (SEM); the change of oil fi lm NRCS was modulated by its dielectric constant and surface roughness, in which the dielectric constant showed a dominant eff ect. The relationship between thickness and NRCS of oil fi lm was studied under two experimental conditions. The diff erences of NRCS between oil fi lm and adjacent seawater (  σ 0 ) and the damping ratio (DR) were found to have a linear relationship with oil thickness, which were best in the vertical polarization mode (VV) at 45° incident angle during the quantitative crude oil homogeneous emulsifi cation process. In the natural emulsifi cation process of continuous oil spill in which oil fi lm was mixed with both crude oil and emulsifi ed oil, an empirical equation of oil fi lm thickness is preliminarily established. The  σ 0 , DR, and the empirical equation of oil fi lm thickness were applied to the marine continuous oil spill incident on a 19-3 oil platform with spaceborne SAR image and successfully explained the distribution of the relative thickness of the oil fi lm.

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Interpreting sea surface slicks on the basis of the normalized radar cross‐section model using RADARSAT‐2 copolarization dual‐channel SAR images

Cited by 20 publications

References 31 publications

Wave Breaking in Slicks: Impacts on C-Band Quad-Polarized SAR Measurements

Wave Breaking in Slicks: Impacts on C-Band Quad-Polarized SAR Measurements

Mineral Oil Slicks Identification Using Dual Co-polarized Radarsat-2 and TerraSAR-X SAR Imagery

Experimental research on oil film thickness and its microwave scattering during emulsification

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