An Exploration of Charge-neutral Atmospheric Propagation Path Error Correction Method for Interferometric Radar Altimeter

The Interferometric Radar Altimeter (IRA) is an innovative remote sensing sensor for the ocean that can observe mesoscale and submesoscale (meso-submesoscale) ocean dynamic processes. However, the medium error is always a limiting factor for the measurement accuracy of sea surface height (SSH), from traditional nadir radar altimeter to IRA. This paper discusses a type of medium error caused by the charge-neutral atmosphere, an approximately non-dispersive medium. According to research, the charge-neutral atmospheric propagation path produces three types of SSH errors for IRA: differential delay error, path delay error, and path bending error. Since the variation of SSH at meso-submesoscale is usually at the centimeter level, the above three types of SSH errors must be corrected. However, due to the difference in the observation regime, the along-track correction method of the traditional subsatellite ZND is no longer suitable for IRA. Meanwhile, the positioning deviation in the IRA interferogram caused by line-of-sight (LOS) delay restricts the correction accuracy of the related error. Therefore, this paper proposes an iterative correction algorithm based on the spatial stochastic model (ICA-SSM) as an exploration of the charge-neutral atmospheric propagation path error correction method for IRA. The numerical simulation result combined with the system parameters of SWOT illustrates that this method can not only ensure the centimeter-level altimetry accuracy of IRA, but also suppress the distortion of ocean phenomenon caused by related errors, and improve the measurement performance of IRA.