A first look at river discharge from SWOT satellite observations

The SWOT satellite has the potential to transform global hydrologic science by offering simultaneous and synoptic estimates of river discharge and other hydraulic variables. Here, we present the first discharge estimates from SWOT during the initial orbital configuration of the mission. A preliminary accuracy assessment from April of 2023 shows results consistent with pre-launch expectations: SWOT discharge can track dynamics without any gauge information. It captures discharge magnitude correctly in some cases but has bias in others. Correlations in a set of representative cases of SWOT performance ranged from 0.42 to 0.89, while the normalized root mean squared error was between 4.6% and 67.5%. Although we were very limited in the selection of river reaches, the feasibility of estimating river discharge from SWOT and these promising initial results are encouraging. As SWOT data are improved by reprocessing, we argue that the outlook for SWOT discharge is bright.