Validation of Mainland Water Level Elevation Products From SWOT Satellite

The surface water and ocean topography (SWOT) satellite, carrying a Ka-band radar interferometer, is designed to detect global hydrological, ecological, and climatic changes through high-precision measurements of water elevation level and to promote the sustainable use and conservation of water resources. The accuracy of water level elevations of inland from SWOT was verified globally in this article by comparing SWOT data with Hydroweb and G-REALM data, so as to better utilize the advanced global remote sensing observation capabilities of SWOT in hydrology. Through spatiotemporal matching validation, this experiment validates the SWOT data by time series within different regions, confirming that SWOT observations have an accuracy of more than 99% for inland lakes and rivers globally in eight geographic subregions. Compared with Hydroweb and G-REALM, SWOT's lake products have mean absolute error of less than 0.5 and 0.3 m, as well as a root mean square error (RMSE) of less than 1.5 and 2 m, respectively. SWOT's data reduce the error in the measurement of the lake by more than 0.1 m compared with the priori data and improves the accuracy by more than 10%. As for river measurements, SWOT's global average measurement error is less than 0.15 m, with an RMSE of less than 1.5 m, providing highly accurate measurements for rivers in most regions of the world. Overall, the product of SWOT can provide high-precision heights of terrestrial water bodies, which is of great significance for small inland water body measurements, global water quantity monitoring, and water circulation research.