Two-Dimensional Radar Backscattering Modeling of Oil Slicks at Sea Based on the Model of Local Balance: Validation of Two Asymptotic Techniques for Thick Films

The problem of hydrodynamic modeling of the surfaces of oil films at sea is treated by using physical models, namely, the model of local balance and the Elfouhaily spectrum model for describing the clean sea surface. Then, this refined hydrodynamic modeling of the surfaces of contaminated seas makes it possible to derive electromagnetic modeling by considering thin oil films on the sea surface. Two simplifying approaches in dealing with this complex double-layer problem are described, called “thin-layer” and “classical” approaches. These two approaches, both having the advantage of reducing to a single-layer problem, are compared with a rigorous reference method for 2-D problems. Thus, their validity domains are analyzed in terms of incidence angle, wind speed, polarization, frequency, and oil viscosity. Finally, the polarimetric behavior of both clean and contaminated seas is analyzed; following recent work led on satellite measurements, the same features are retrieved, and the influence of incidence angle, frequency, and oil viscosity can be studied.