Ocean Wave Parameters Retrieval from Sentinel-1 SAR Imagery

In this paper, a semi-empirical algorithm for significant wave height (H-s) and mean wave period (T-mw) retrieval from C-band VV-polarization Sentinel-1 synthetic aperture radar (SAR) imagery is presented. We develop a semi-empirical function for H-s retrieval, which describes the relation between H-s and cutoff wavelength, radar incidence angle, and wave propagation direction relative to radar look direction. Additionally, T-mw can be also calculated through H-s and cutoff wavelength by using another empirical function. We collected 106 C-band stripmap mode Sentinel-1 SAR images in VV-polarization and wave measurements from in situ buoys. There are a total of 150 matchup points. We used 93 matchups to tune the coefficients of the semi-empirical algorithm and the rest 57 matchups for validation. The comparison shows a 0.69 m root mean square error (RMSE) of H-s with a 18.6% of scatter index (SI) and 1.98 s RMSE of T-mw with a 24.8% of SI. Results indicate that the algorithm is suitable for wave parameters retrieval from Sentinel-1 SAR data.