This dataset provides the 1Hz time series of the sea surface height measured by a surface buoy equipped with a Global Position System (GPS). The GPS-mooring was deployed by the SWOT prelaunch field campaign conducted near the SWOT CalVal crossover location, about 300 kilometers west of Monterey, California between September, 2019 and January, 2020. The GPS measurements represent the total sea surface height including the Inverted barometer component. The same mooring also carries fixed-depth CTD sensors https://doi.org/10.5067/SWTPR-CTD11. They were used together with atmospheric pressure and bottom pressure measurements to close the sea surface equation (Wang et al., 2022). The campaign also deployed another two CTD moorings, a slocum glider, and a Pressure Inverted Echo Sounder (PIES).