Observed and Computed M₂Tidal Currents in the North Sea

M2 tidal elevations and currents have been computed using a three-dimensional hydrodynamic numerical model of the northwest European shelf. These have been compared with observational data from tide gages and current meter rigs moored in different positions in the North Sea. The observed and computed current ellipse parameters (semi-major and semi-minor axes, axis orientation and sense of rotation) are tabulated and compared, and found to be in good agreement with each other. An analysis of amplitude errors derived from computed and observed M2 tidal elevations shows a marked difference in the distribution of phase errors, as derived, on the one hand, from the present three-dimensional model and, on the other hand, from an earlier two-dimensional model covering the same region.