Simulated surface salinity data in the offshore Zhejiang for the winter months of 2019-2022 (December, January and February) and buoy observed data for 2020 winter.

The simulated salinity data were obtained from the Finite Volume Coastal Ocean Model (FVCOM) with a time interval of 1 day and a spatial range of 120-124°E, 27-32°N with a spatial resolution of 0.1°. The modeled area includes the Bohai, Yellow, and East Seas, as well as parts of the Japan/East China Sea and the Pacific Ocean.In the sigma-stretching coordinate system, 20 vertical layers were specified in the water column. The General Bathymetric Chart of the Oceans provides high-resolution (~0.5 km) bathymetric data. The driving forces for the numerical simulation included tides, river flow, surface heat flux, winds, and open boundary conditions. The harmonic constants of 11 major tidal constituents (M2, S2, N2, K2, K1, O1, P1, Q1, M4, MS4, and MN4) derived from the Oregon State University global inverse tidal model TPXO.7.0 were employed.Daily average flows of the Changjiang and Yellow Rivers were taken from the publicly available observation data of the Datong Hydrological Station (http://yu-zhu.vicp.net/). Other rivers were not included due to their small flows. Daily average heat flux comes from objectively analyzed air-sea fluxes, while 3-hour wind stress and 10 m wind speed data were drawn from the ERA-Interim reanalysis.Open boundary conditions for factors including daily temperature, salinity, and fluxes, were obtained from the Hybrid Coordinate Ocean Model and interpolated to the FVCOM model grid points.The initial temperature and salinity were obtained from the Hybrid Coordinate Ocean Model; initial velocity was set to zero in this study. The model was spin up over 30 model days, with a sponge layer used at the lateral boundaries. The model time step was 15 seconds for the two-dimensional barotropic mode and 90 seconds for the three-dimensional baroclinic mode. All output fields were processed with a tidal filter to remove tidal oscillations.The observed data are from six buoy stations. The locations of the buoys are available in the paper: Synoptic Cross-shore Movements of Outer Salinity Fronts in the China’s Changjiang River Plume. The data are daily averages that have been processed. The first column in each variable is time and the second column is sea surface salinity.