The Influence of Changing Sea Surface on the Gravity Field Derived from SWOT.

The Surface Water and Ocean Topography (SWOT) mission, with its short repeat period, is more sensitive to dynamic sea surface variations and more prone to introducing spurious signals. Therefore, considering time-varying effects is crucial when constructing a stable gravity field from SWOT data. This study explores the impact of these effects using model correction and stacking methods. The results show that incorporating time-varying effects enhances deflection of the vertical (DOV) by approximately 40% in high time-varying areas and improves gravity anomalies by 0.26 mGal (~9%). Furthermore, a single model-corrected cycle outperforms the accumulation of a year’s data in high-variability regions. In contrast, the stacking method introduces more outliers at the edges and nadir, making it less effective than the model correction method. Finally, the analysis of a 40°×40° region in the eastern Pacific highlights the need for corrections in regions where the standard deviation of the sea level anomaly exceeds 20 cm. This study demonstrates that accounting for time-varying effects can significantly improve the precision of DOV and gravity anomaly fields in high-variability areas, contributing to a more accurate marine gravity field.