Abstract: In light of the challenge in establishing a time series of water level for hydrological research caused by the slope of the river surface and the considerable distance in satellite monitoring data, this paper puts forward a correction approach to construct a river level correction model based on ICESat-2 altimeter data. The global altimeter data of ICESat-2 from 2018 to 2023 is employed. Taking the lower reaches of the Yellow River as the research area, a river level correction model is developed to compensate for the ground track variations of the ICESat-2 altimeter satellite. In combination with the monorail data of Sentinel-3A/B from 2016 to 2024, the water level time series at four hydrological stations in the study area is constructed, and the accuracy verification and change analysis are conducted. The results demonstrate that the accuracy of the multi-orbit data of ICESat-2 corrected by the corrected model is comparable to that of the Sentinel-3A/B monorail data, with the maximum correlation coefficient being 0.96 and the minimum root-mean-square error being 0.23 and 0.21 m respectively. The average time resolution of the constructed water level time series can reach 13 days. From 2016 to 2024, the water level in the Henan section of the lower reaches of the Yellow River exhibits a seasonal variation law of rising first and then decreasing, and rainfall and evaporation are the main factors causing the water level change.

Key words: water level correction model, ICESat-2, Sentinel-3A/B, time series, water level variation