A benchmark dataset of water levels and waves for SWOT validation in the St. Lawrence Estuary and Saguenay Fjord, Quebec, Canada

Abstract. This manuscript presents a comprehensive and evolving novel in situ dataset of water levels and wave parameters collected from March 2023 onward in the St. Lawrence Estuary and Saguenay Fjord (Quebec, Canada), supporting validation activities for the Surface Water and Ocean Topography (SWOT) satellite mission. The dataset integrates water level measurements from 18 barometrically-compensated pressure transducers and, where possible, corrected for water density using collocated salinity and temperature data, supplemented with 13 GNSS-Interferometric Reflectometry (GNSS-IR) sensors. All water level data are referenced to a common vertical datum via real-time kinematic (RTK) GNSS corrections. Three directional wave buoys provided supplementary observations of surface wave conditions, including bulk parameters and directional spectra. Quality-controlled and rigorous processing protocols were implemented across all sensor types, with particular attention to referencing accuracy and correction for environmental influences. The observational network has the densest spatial coverage of water level and wave measurements ever achieved in this region, offering unprecedented opportunities for validation of SWOT’s nadir and wide-swath altimetry products, as well as for hydrodynamic model calibration and spatio-temporal studies of tidal and wave processes in complex estuarine environments. With ongoing data collection, this evolving benchmark dataset is publicly accessible at https://doi.org/10.5281/zenodo.18225505 and will be periodically updated with new observations, to facilitate extended SWOT science validation and support a broad range of estuarine research applications.