Cross-Track Error Correction and Evaluation of the Tiangong-2 Interferometric Imaging Radar Altimeter

The Interferometric Imaging Radar Altimeter (InIRA) carried on the Tiangong-2 Space Laboratory can observe three-dimensional sea surface topography over a swath tens of kilometers wide. The InIRA represents a test mission that will provide valuable experience for the design and data processing technology of future wide-swath altimeters. In addition to the tropospheric delay, ionospheric delay, and sea state bias (SSB) that affect traditional altimeters, InIRA was affected by the cross-track error derived from roll error, baseline length error, and interference phase error, which had to be properly corrected. In this letter, range error correction based on correction models and cross-track error correction based on the reference topography data (RTD) method were applied to a 15-day InIRA dataset and evaluated using the Jason-2, Jason-3, Saral/AltiKa, and Sentinel-3A. The results showed that the standard deviation (STD) between corrected InIRA and the combined dataset was 7.96 cm after eliminating the influence of tides and dynamic atmospheric correction (DAC), which was comparable to nadir altimeter measurement accuracy.