The Research Progressin Calibration/Validation of Interferometric Altimeter

The satellite altimeter technology is evolving from the nadir to interferometric wide swath altimetry,which make it possible to monitor the two-dimensional sea surface height and water surface elevationof rivers/lakes with high resolution and accuracy. For oceanographic study, the monitoring of submesosacle signals may be performed in the U.S.—French SWOT (Surface Water and Ocean Topography) and the follow-up Chinese ^"Guanlan^" missions. The calibration/validation (Cal/Val) is one of important components of such satellite missions. Traditional Cal/Val methods for nadir altimeters are mainly based on the tide gauge, GNSS buoy and transponders, and are compared point by point with the satellite data. However, these Cal/Val methods are difficult to satisfy the requirements of SWOT-like missions. Innovated Cal/Val methods have been tested with the air borne sensors,which can fly over the ocean and land water surfaces. This study summarized the research progress in the field of Cal/Val methods for interferometric altimeters, and expected that this work might serve as a reference to future missions.