Wind wave-induced artifact surface velocity (WASV) is an important component of the sea surface motions detected by synthetic aperture radar (SAR) systems. Understanding the characteristics of the interference of WASV on SAR current velocity estimates is necessary to improve the accuracy of retrievals. In this study, we assessed and analyzed the sensitivity of WASV in C-band along-track interferometric (ATI) SAR to radar configuration, wind field, swell field, and a wave spectrum model. Results showed that the influence of wind speed on WASV increased with the current velocity. The swell also affected WASV, especially at higher wind speeds; WASV was more strongly influenced by swell amplitude than by swell wavelength. In terms of radar configurations, results showed that VV polarization was more suitable than HH polarization in the estimation of WASV. The interference of WASV was minimal at moderate incidence angles (around 40°), and an appropriate ATI baseline selection was also given. The WASV was more strongly influenced by sea states than by the wave spectrum model or by a spreading function. The findings of this study improve our understanding of WASV and provide a reference for the design of future ATI SAR current measurement instruments and projects.

Synthetic aperture radar (SAR) provides high-resolution, two-dimensional imaging of the sea surface so it can obtain a refined radial velocity field on the sea surface. As the first civil satellite launched by China, GF-3 can provide along-track interferometric (ATI) mode to realize current measurement. We carried out the inversion of radial velocity on the sea surface based on the dual-channel measured SAR data of the GF-3 satellite, and the inversion of radial current velocity on the sea surface is realized using the ATI and Doppler centroid anomaly (DCA) methods. The comparison of the inversion results reveals that the two methods are in high consistency, with the average correlation coefficient greater than 0.7, and the highest correlation coefficient above 0.8. Further, the accuracy evaluation was carried out using synchronized high-frequency surface wave radar (HFSWR) data. The root-mean-square error between the ATI method and HFSWR is 0.1338 m/s, and the relative mean deviation is 11.63%. The results show that the ATI method has better current measurement accuracy than the DCA method, and it can be used to obtain fine radial current field information on the sea surface.