High-precision TOPSAR radial velocity estimation method based on raw data

Doppler Centroid Anomaly (DCA) method based on synthetic aperture radar (SAR) data provides Doppler radial velocity information of the ocean surface, which is of great significance for observing oceanographic features such as currents and eddies. However, due to the complex azimuth antenna steering mechanism of the TOPS mode, systematic errors will be introduced, resulting in significant scalloping in the ocean surface Doppler radial velocity field provided by the Level-2 OCN product. The mainstream method is to perform image-level processing to remove the scalloping, but image-level processing is prone to misinterpreting the real linear change of the current field in the sea surface scene as scalloping, thereby losing information about the edges and texture of the current. In order to further improve the Doppler radial current field accuracy of the TOPS mode, this paper presents a full-process method from SAR raw data to Doppler radial field retrieval. The precise modeling of the antenna steering process can correct the phase error in the focused image and eliminate the scalloping in the current fields. The experimental results show that the method can achieve ideal processing effects, effectively eliminating the scalloping compared with the OCN product processing results, and providing more rich morphological information compared with image-level processing results, proving the effectiveness and precision of the method.