Microwave oil film thickness (OFT) inversion has always been a difficult problem. Based on the empirical relationships between the oil film’s normalized radar cross section (NRCS) obtained from a field experiment and the inversion of the oil film thickness retrieved from a synchronous optical image, several rules have been identified. Inversion formulas suitable for different oil film thickness ranges under certain conditions are established. Following experimental data verification, our results show that the correlation coefficient is greater than 0.99, and the root mean square error is less than 15 µm.

We aim to apply the research results to the oil spill event observed by spaceborne SAR.

The damping ratio (DR) of a spaceborne synthetic aperture radar (SAR) image is used as a bridge to establish the correlation between the optical oil film thickness and the SAR-inverted oil film thickness. By synchronizing SAR and optical oil spill inversion data, the oil film thickness obtained from SAR data is closer to the measured data. It is found that the oil film thickness of the SAR image can explain the spatial distribution of the oil film. This study provides a new idea for spaceborne SAR oil film thickness inversion.