Cross-track error estimation of wide-swath altimeters based on reference topography data

Wide-swath altimeters, which can provide unprecedented fine-scale data for marine research, are an important development direction in the new generation of satellite altimeters. However, the cross-track error, one of the main error sources for wide-swath altimeters, must be fully estimated and corrected. Error estimation based on reference topography data (RTD) is effective. Since the sea surface is dynamic, the time difference between the RTD and the measured topography will cause the cross-track error to be misidentified. Limited by the temporal or spatial resolution, averaging the gridded RTD can improve its overall performance but will weaken the instantaneous characteristics. Therefore, it is necessary to select RTD with an effective time interval according to the changes in the surface topography within the target area. This paper uses gridded mean sea surface data and daily sea level anomaly data to construct input data sets and generate output data with errors in different experimental areas through the SWOT Simulator. Two RTD methods with different time spans are used to estimate and correct the cross-track error, and the effective time is calculated by the root mean square error of the residual part. The results show that the effective time is approximately 3 days in high-energy regions but can be extended to more than 10 days in low-energy regions.