Error Analysis of Dynamic Sea Surface Height Measurement by Near-nadir Interferometric SAR

High precision measurement of sea surface is great significance for the remote sensing of spaceborne ocean. The near-nadir spaceborne interferometric synthetic aperture radar (InSAR) can be used to measure Sea Surface Height (SSH) with centimeter-level accuracy in wide area. Compared with terrestrial interferometry, the vital difference of ocean measurement is the random motion of ocean surface waves. For remote sensing, the motion of sea surface will bring bias to the imaging and interference process of InSAR, leading to height measurement error eventually. In this paper, we have study the error caused by dynamic sea surface and the influence of measurement accuracy on InSAR. Based on the characteristics of ocean surface and the working mechanism of InSAR, the theoretical model of motion error is established. In the ka-band Strip-map model, the error of various incident angles and sea states are simulated. Form the experiment results, we can find that the error of altimetry is increasing by the increase of sea surface wind speed. Under the same sea states, the error of sea surface height measurement increases with expanding the angle of incidence. And the Doppler centroid frequency of SAR signal has a great impact on errors. The results of theoretical analysis and experimental simulation have provided feasible suggestions for the design of InSAR system and error budget for sea surface height measurement in the future.