A New Concept of Full Ocean Current Vector Retrieval With Spaceborne SAR Based on Intrapulse Beam-Switching Technique

摘要

Synthetic aperture radar (SAR) has proven to be an important tool for the retrieval of ocean surface currents. However, existing spaceborne SAR systems can usually measure only one component of an ocean current vector. In this article, we propose a new concept of dual-look spaceborne SAR system for ocean surface motion remote sensing. The key of the proposed SAR system lies in the use of a technique called intrapulse beam switching (IPBS) implemented by a phased array antenna. One example for the application of the proposed IPBS-based SAR system is its combination with the Doppler centroid anomaly (DCA) method. Through the combination, the DCA method, which in its conventional version can measure only the radial component of a current vector, is generalized to measure full ocean current vectors. A system design example and its performance evaluation demonstrate that the accuracies for ocean surface velocity vector measurement better than 5 cm/s in both azimuth and range, and better than 10° in velocity direction for a mild current, and a swath width of about 100 km, can be achieved. A comparison with other beam-generating schemes indicates that a relatively large swath width, without compromising the current-measuring accuracy, can be achieved by the proposed SAR system with one single antenna array and one single physical output channel—a feature that means a high level of integration which in turn allows for the flexibility to operate this system in multiple SAR modes.