Authors: Song Shu*, Appalachian State University, Hongxing Liu, the University of Alabama
Topics: Remote Sensing, Water Resources and Hydrology, Cryosphere
Keywords: satellite radar altimetry, lake water levels, performance assessment, long time series of estimates
Session Type: Paper
Presentation File: No File Uploaded
Satellite radar altimetry has been widely used in the monitoring of lake water levels in the past decades. Thirteen satellite missions have been launched since 1985 with different types of radar altimeters onboard. The performances of the different altimeters over inland lakes have been discussed in a number of previous studies. However, most of them focused on one or two satellite missions. No study investigated comprehensively the capabilities of all the missions in the retrieval of water levels. In this study, we evaluated eleven of the thirteen missions over twelve lakes in four countries. The lake level estimates produced by each retracker of the eleven missions were compared with the in-situ gauge measurements. The results show that the model-free retrackers outperform the model-based retrackers across the twelve lakes for all missions. The contrast between them is marked particularly over small lakes. Sentinel-3 gave the best results, followed by SARAL, ENVISat, Jason-1 and Jason-2 with regards to r and RMSE. ERS-1 and ERS-2 provided more accurate lake level estimates than T/P over small lakes, while on large lakes T/P is a better option due to its lower rate of missing estimates and shorter repeat cycle. GeoSat and GFO both have extremely high rate of missing estimates. With a full consideration of the performance and the operational duration of each mission, Jason-2 is recommended as the reference mission to estimate the biases between these eleven missions, in order to construct the long time series of lake level estimates for the ungauged lakes.