Effect of satellite altimetry sampling error in estimating reservoir storage and outflow

Abstract

The potential of satellite imagery to complement the in-situ gauge networks in monitoring freshwater is well established. However, Temporal Sampling (TS) intervals of satellite altimetry impart significant uncertainty compared to daily or sub-daily in-situ gauge measurements. This study examines the effect of infrequent TS from satellite altimetry, i.e. 10-Day (Jason-2/3), 21-Day (SWOT), 27-Day (Sentinel-3A) and 35-Day (SARAL/AltiKa) for the evaluation of reservoir storage and outflow. The metrics of Relative Error (RE), Root Mean Squared Deviation (RMSD), and the correlation between altimetry-based and in-situ observations have been used for the evaluation. Results show that the altimeters having a high TS frequency, such as 10-Day or 21-Day, performed well with RMSD less than 0.2 m and correlation more than 98% in estimating satellite-based storage and outflow compare to coarse 27-Day or 35-Day TS. This study improves the understanding of sampling error in satellite altimetry, which has immense potential for future SWOT altimeter mission.