The experiment contains baroclinic hindcast simulations of the North Sea by the hydrodynamic model HAMSOM (Pohlmann, 2006) for the period 1948-2007. HAMSOM was set up at a spatial resolution of 20' x 12' and with 19 vertical levels (5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 60, 75, 100, 150, 200, 250, 350, 600 and 1000m, lower boundary level). The data-set contains hourly output of temperature, salinity, u- and v-component (3-dim) and water level (2-dim). At the open boundaries, lateral boundary conditions are obtained from a coarser, large-scale Northwest-European shelf sea model driven by climatological temperature and salinity obtained from Levitus (1982). For water levels, in addition the eight significant tidal constituents (M2, S2, N2, K2, K1, O1, Q1 and P1) are included and weather effects are accounted for by using wind and pressure fields from the NCEP/NCAR Reanalysis 1 (Kalnay et al., 1996). Due to technical reasons at the lateral boundaries the water level was added by 0.5m. Atmospheric forcing was obtained from NCEP/NCAR Reanalysis 1 data-set comprising near-surface air-temperature, humidity, cloud cover, precipitation, sea level pressure and near surface wind speed and direction. The output format is netCDF.