Abstract:
Two-dimensional (2-D) water surface elevations (WSEs) can be measured for the first time using a new generation of radar altimeter, which uses the interferometric synthet...Show MoreMetadata
Abstract:
Two-dimensional (2-D) water surface elevations (WSEs) can be measured for the first time using a new generation of radar altimeter, which uses the interferometric synthetic aperture radar (InSAR) technique on near-nadir swath to measure elevations of both the inland surface waters and the ocean with unprecedented swath and spatial resolution. The interferometric imaging radar altimeter (InIRA) in the Tiangong-2 space laboratory of China is the first spaceborne interferometric radar altimeter, which was launched in 2016. Calibration is essential to a guarantee of the measurement accuracy. Not only the cross-track errors, but also the along-track errors have to be estimated and corrected. This letter proposes a correction method to remove the azimuth time shift of the radar system using geographic positions of the surrounding lakeshores and riverbanks. Real acquisitions of InIRA over the largest inland lake of China, i.e., the Qinghai Lake, have been selected to validate the method. Both azimuth and range system time errors, the media delays, and the cross-track phase errors have been estimated and corrected on the level-1 complex products. The derived 2-D WSEs over an area of ~400 square kilometers have been compared with the high-resolution data of Sentinel-3A synthetic aperture radar altimeter (SRAL). The validation results have shown good agreements in both along-track and cross-track directions with a root mean square error of 28.1 cm and a mean absolute error of 22.7 cm.
Published in: IEEE Geoscience and Remote Sensing Letters ( Volume: 20)