ICESat?2 Based River Surface Slope and Its Impact on Water Level Time Series From Satellite Altimetry

The water surface slope (WSS) of rivers is essential for estimating flow velocity and discharge. It also helpful as a correction applied to range measurements satellite altimetry missions derive level time series at virtual station. Using radar altimetry, WSS can only be roughly estimated limited wide because its coarse spatiotemporal resolution. In contrast, the lidar sensor onboard Ice, Cloud, Land Elevation Satellite 2 (ICESat-2) observe small rivers. ICESat-2's unique measurement geometry with six parallel laser beams, we instantaneous along across satellite's ground track, time-variable (with an average 5 days records in studied epoch between October 2018 2021), on reach-scale. Although method globally, this study 815 reaches Europe North America where sufficient validation data available. We compare ICESat-2 derived from multiple gauges constant “SWOT River Database.” For 89% reaches, used estimate median absolute error 23 mm/km. show possible performance gain stations (VS) “Database Hydrological Time Series Inland Waters” (https://dahiti.dgfi.tum.de), applying satellites' track variability. correct 137 VS yield improvements root mean square by up 30 cm or 66%.