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

Abstract

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.

Remote Sensing of Organic Films on the Water Surface Using Dual Co-Polarized Ship-Based X-/C-/S-Band Radar and TerraSAR-X

“…In [32] where Radarsat (RS) and TerraSAR-X (TS) acquisitions of slicks were analyzed any noticeable effect of surface film on the non-Bragg component was not revealed. However, a significant reduction of NBC in films slicks was reported later in [33]. It was obtained in [33], based on analysis of Radarsat-2 observations, that NBC and BC contrasts in film slicks of different origin are comparable to each other.…”

“…Remote sensing of marine films, both biogenic pollutions and oil spills, is aimed to identify the films and to quantify their characteristics, and is a very important and urgent problem actively discussed in the literature (see, [1][2][3][4][5][6][7], and references therein). This problem, however, film slick remote sensing some observations with dual-and quad-polarized single-band radars have been carried out (see, e.g., [31][32][33]). In [32] where Radarsat (RS) and TerraSAR-X (TS) acquisitions of slicks were analyzed any noticeable effect of surface film on the non-Bragg component was not revealed.…”

Dual-Polarized L-Band SAR Imagery for Temporal Monitoring of Marine Oil Slick Concentration

“…The four SAR scenes investigated in this paper have been projected from the slant range to the ground range geometry ( Figure 6). The spilled area has been automatically detected using the polarization difference (in linear unit) between VV and HH channels [10,12,14,31] and the temporal evolution of the detected area is pictured on Figure 7 in a false color representation: drifting of the MOS Sweeper spill for one hour (from 09:37 to 10:27 UTC) in the morning of 9 June (Figure 7a) and drifting of the spill for four hours (from 09:37 to 13:30 UTC), Figure 7b. The spilled product during the MOS Sweeper exercise has drifted in the North-East direction, under the influence of wind (coming from 250 • , cf.…”

“…A VV polarized image is displayed in Figure 11 together with the experimental PR and the estimated oil concentration maps. A detection mask has first been applied, based on the thresholding of the polarization difference [10,12,14,31]. The ranges of variation of PR values and oil concentrations have been reduced to 0.15-0.35 and 20-80%, respectively, to enhance the visualization.…”

Comprehensive Ground-Space Monitoring of Anthropogenic Impact on Russian Black Sea Coastal Water Areas

“…This method is based on the wavelet transform allowing for studying nonstationary phenomena [6,23]. -A method of sea surface multi-polarized radar imagery processing, when normalized radar cross-section (NRCS) is given as a sum of Bragg scattering-related polarized scattering and non-polarized scattering related with wave breaking [20]. -A method of comparing sea surface structure statistical characteristics obtained using in situ methods and satellite data obtained using sea wave dispersion relationship.…”