Validation of Just-Released SWOT L2 KaRIn Beta Prevalidated Data Based on Restore the Marine Gravity Field and Its Application

Abstract

A part of the preprocessed beta Ka-band radar interferometer (KaRIn) data (7 September–21 November 2023) for the surface water and ocean topography (SWOT) mission has been released. To validate the performance of SWOT L2 KaRIn beta prevalidated data (beta data), this study conducted various experiments, including inverting the ocean gravity field and seafloor topography from these data, validating the accuracy of the deflections of the vertical (DOV) by DOV products of Scripps Institution of Oceanography (SIO). The root mean square of differences between north–south and east–west components is about 1.83 urad and 2.71 urad, respectively. The precision of gravity anomaly (SWOT_GA) is about 5.07 mGal compared with shipborne gravity. The results derived from one-cycle data are comparable with those obtained from a substantial dataset accumulated by traditional nadir altimeters. The accuracy of seafloor topography inverted from SWOT_GA is about 68 m validated by shipborne depth, which is almost the same as the topography obtained from SIO_GA and SDUST2021GRA. The results of multiple experiments have demonstrated that beta data can be used to compute high-precision ocean gravity fields and seafloor topography products. This proves the success of the first operational run of KaRIn and the capability of SWOT to support studies related to ocean science. The current evaluation results are based on beta data. The prevalidated data will be more accurate after further calibration, which will lead to higher accuracy of the inverted gravitational field products in the future.

Keywords

• Gravity anomalies (GA) and bathymetry
• performance of SWOT L2 Ka-band radar interferometer (KaRIn) beta prevalidated data
• radar interferometry
• surface water and ocean topography (SWOT) mission