A Closed-Form Expression Based Height Inversion for SAR Altimeter

Synthetic aperture radar (SAR) altimetry has the capability of altimetry with a good accuracy, especially for the ocean scene. The model-based methods are widely used in the height inversion of the altimetry data due to the strong correlation with physical process. However, the bias of the model will significantly decrease performance of height inversion. In this work, we introduce a novel height inversion algorithm based on the closed-form expression, which is an effective model for measuring radar echoes. Effective initialization strategy expands the application scope, and two-step retracking algorithm is designed which could be used in an iterative least-squares algorithm. In essence, this method aims to remove the coupling between the parameters in closed-form expression. Experimental results using the simulated data indicate that this proposed method has wider application range under different signal-to-noise condition. In addition, precision of two-step method remains stable compared with traditional method, which has potential for actual altimetry system.