Performance of marine gravity anomalies extracted from SWOT KaRIn data of science phase in the Gulf of Mexico

The Surface Water and Ocean Topography (SWOT) satellite, employs wide-swath interferometric altimetry to measure sea surface height (SSH) with high spatial resolution. This study proposes an optimized method for computing geoid gradients (GGs) tailored to the high-resolution SWOT data, which calculates GGs using pairs of SSH observations separated by a defined distance interval. The performance of KaRIn data from the science phase is evaluated for marine gravity anomaly (GA) inversion. Based on KaRIn data from SWOT cycles 1-18 (July 2023-July 2024), the Gulf of Mexico GA model (SWOT_GRA) is developed and compared with models derived from SARAL (2016-2023) and Cryosat-2 (2010-2023) data. Results indicate that the optimized GGs computation method enhances GA accuracy, while combining along-track and cross-track GGs reduces meridian-prime disparities. The SWOT_GRA model achieves an accuracy of approximately 3.18 mGal when compared to shipborne gravity data, representing an 8.5% improvement over the Cryosat-2 and SARAL models. These findings demonstrate that GA inversion using one year of SWOT data surpasses the accuracy of results obtained from 13 years of traditional altimetry data, highlighting the potential of SWOT wide-swath data to advance the construction of a unified, high-precision marine gravity field.