SWOT L4 SoS Discharge

The Surface Water and Ocean Topography (SWOT) mission was designed jointly by NASA and Centre National D'Etudes Spatiales (CNES) to provide global mapping of the world's ocean and its terrestrial surface water including rivers, lakes and reservoirs and wetlands

The SWOT Level 4 Sword of Science River Discharge Product is produced by the Discharge Algorithm Working Group (DAWG). It provides global-scale estimates of river discharge derived from the SWOT Level 2 River Single-Pass Vector Data Product, in reanalysis mode, covering an entirely reprocessed version of SWOT data. The discharge time series are produced by the six flow law parameter estimate (FLPE) algorithms and a single ‘consensus’ estimate that represents the ‘SWOT Discharge.’. The products include versions based either on unconstrained or gauge constrained estimates that leverage in-situ measurements.

Sword of Science data products are generated from the open-source SWOT Confluence program and contain river discharge parameter estimates as well as discharge time series for both river reaches and river nodes, following the SWOT River Database (SWORD) structure and naming conventions. It is indexed on the same reach and node identifier dimensions found in SWORD. Outputs from Confluence are organized into groups corresponding to modules in the SWOT-Confluence processing software. Modules are described in the Confluence Module Documentation. These L4 discharge time series are available as netCDF, and released with an estimate of discharge matching each quality-controlled SWOT observation. Thus, the temporal frequency of discharge estimates is different for each river.

Granules from both constrained and unconstrained branches are composed of prior information (e.g., mean annual flow predicted by global hydrological models) and the resulting discharge estimates. Priors and results files for both constrained and unconstrained branches are available in netCDF format. Note that currently, prior files are not available and will be added to the catalogue soon.

Development of the SWOT Confluence program as well as the Sword of Science data products was funded by NASA’s Advanced Information Systems Technology (AIST) program. To cite this dataset, please use the following DOI: .