A New Model for Complex Permittivity of Oil-Seawater Emulsions: A Framework for Quantitative Sar Monitoring of Marine Oil Spills

Abstract

A complex permittivity model for oil-seawater emulsions is crucial for analyzing marine oil spills in microwave remote sensing, especially in SAR (Synthetic Aperture Radar). However, the dielectric behavior of oil-seawater emulsions is highly complex, and most existing models remain empirical, with limited theoretical foundations. We derive a new theoretical model for the complex permittivity of oil-seawater emulsions based on Maxwell’s equations and charge conservation under a small-perturbation approximation, and apply it to analyze the emulsion’s dielectric properties. The complex permittivity was measured experimentally on oil-seawater emulsions (0–100% oil volume fractions) at 0.3–1.5GHz. Our model was validated against experimental data and compared with three empirical models: Maxwell–Garnett, series–parallel, and exponential models. The proposed complex permittivity model demonstrates improved predictive accuracy across a wide range of oil concentrations and theoretical validity extending to 30GHz, thus providing a more reliable basis for quantitative SAR monitoring of marine oil spills.

Keywords: Complex Permittivity, Theoretical model, Oil-seawater Emulsions, SAR Imagery