Assessing the consistency of coastal sea surface height measurements from SWOT altimetry and tide gauges along the U.S. East Coast

Abstract

In nearshore environments, the limited accuracy of traditional satellite altimetry in monitoring coastal sea-level changes restricts its application. The wide-swath, high-resolution measurements from the Surface Water and Ocean Topography (SWOT) satellite provide a new understanding of coastal sea-level variability. This study evaluates the capability of SWOT to observe the instantaneous sea surface height (SSH) along the U.S. East Coast between August 2023 and December 2025. The SWOT Level-2 KaRIn low-rate sea surface height expert data show good agreement with the results validated by tide gauges (TGs). In all pooled observations from the 12 TG stations, the Pearson correlation coefficient (R) between the SWOT and the TG measurements was 0.998, with a root mean square error (RMSE) of 0.295 m and a mean absolute error (MAE) of 0.224 m. These results demonstrate that, even under complex nearshore environmental conditions, the SWOT can effectively capture the SSH variability and exhibits considerable potential for coastal observations.