On the Use of Dual Co-polarized Radar Data to Derive a Sea Surface Doppler Model—Part 2: Simulation and Validation

The Doppler shift obtained from synthetic aperture radar (SAR) measurements comprises the combined contribution to radial motion of ocean surface induced by sea state (wind waves and swell) underlying currents. Hence, obtain reliable estimates current, sea-state-induced shifts must be accurately estimated eliminated. In this study, we use a semiempirical dual co-polarization velocity (DPDop) model, presented in companion paper, calculate using buoy-measured wind speed, direction, wave spectra. DPDop model-simulated are compared with collocated Sentinel-1B SAR Wave (WV) mode observations at 24° 37° incidence angles, showing bias -0.24 Hz root-mean-square error (RMSE) 5.55 Hz. This evaluation is also implemented on simplified model same angles. inputs include fields European Center for Medium-Range Weather Forecasts (ECMWF) characteristic parameters (e.g., significant height, mean wavenumber) WAVEWATCH III (WW3). validated ascending descending WV over global ocean. Furthermore, comparisons show that RMSE -0.71 9.25 Hz, respectively. Based accurate correction, current speeds measurements. high-frequency measurements, -0.04 m/s an 0.15 m/s. These results suggest original models can used estimate and, thus, derive retrievals.