SAR raw signal simulation of oil slicks in ocean environments

Abstract

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.

Elastic Properties of Natural Sea Surface Films Incorporated with Solid Dust Particles: Model Baltic Sea Studies

“…Viscoelasticity of the particle-incorporated surfaces revealed time scales of the relaxation processes corresponding to the deformation frequency range 0.9-5.3 Hz relevant to water wave damping in the capillary-short gravity frequency region [34]. It should be noted that the wind waves Marangoni damping effect can not be explained quantitatively only by the dilational moduli obtained in this work; other aerodynamic parameters of the air/film-covered seawater interactions remain to be taken into account [35].…”

Numerical Modeling of Electromagnetic Scattering from Sea Surface Covered by Oil

“…where inc E is the incident wave, s J is the induced current in the surface, the fields E in the upper medium (free space) and 1 E in the lower medium, 0 µ and 1 µ are respectively the permeability of the free space and the lower medium, ω is the radian frequency, r and r′ are the source and observation points respectively, n the outgoing normal to the surface…”

“…To date, many systems have been developed such as SAR (Synthetic Aperture Radar) to detect the presence of the oil spill on the sea surface (Figure 1). To improve the performance of existing systems, it becomes very important to analyze in greater detail the information contained in the electromagnetic field scattered by the sea surface [1][2][3]. In this context, modeling the interaction of electromagnetic waves with polluted seas or not takes all its importance.…”

Robust Semi-Deterministic Facet Model for Fast Estimation on Em Scattering From Ocean-Like Surface

“…With the rapid development of satellite technology, which is employed for gathering information about the terrestrial or extraterrestrial and leads to the possibility of using spacecraft in remote sensing of oceanographic parameters, more and more applications to monitor ocean environment, especially as ocean synthetic aperture radar (SAR) [1][2][3], have been exploited during recent years. To implement these applications, a clear and comprehensive investigation on the physical processes between the electromagnetic waves and ocean surface is desirable.…”

“…Comparatively overall analyses are made on this topic. Franceschetti et al [3,14] presented a facet backscattering model in which the Kirchhoff solution in physical optics approximation is used to compute the facet's backscattering. But, in some cases the scattering properties of the facet are modeled by means of the Bragg phenomena.…”