Observations of Baroclinic Tides in the California Current From the SWOT Satellite Altimeter and In Situ Data

Abstract Sea‐surface topography observations from the Surface Water & Ocean Topography (SWOT) satellite altimeter mission are used to map the baroclinic internal tides in a region off California during the 1‐day calibration/validation orbit phase of the mission. The observations, which cover the period from 30 March through 10 July 2023, reveal a large‐scale internal wave field dominated by waves generated at the Mendocino Fracture zone approximately 500 km north of the region studied. Tidal harmonic constants of baroclinic sea level are derived from mooring observations at four sites within the KaRIn swath and compared with the SWOT data. The harmonic constants from the moorings and altimeter agree qualitatively; however, the SWOT results are significantly uncertain due to long‐wavelength platform errors and non‐astronomical tidal modulations. Spectral analysis of the time series reveal that the phase‐locked tide explains about 75% of the baroclinic sea level variance in the semidiurnal band.