Sensitivity of Tidal Bed Stress Distributions, Near-Bed Currents, Overtides, and Tidal Residuals to Frictional Effects in the Eastern Irish Sea

Abstract

Abstract A three-dimensional nonlinear high-resolution hydrodynamic model of the eastern Irish Sea is used to examine the influence of near-bed viscosity and bottom friction Upon the M2 tide and overrides in the region. Initially, bed stress in the model is related to the depth-mean current, the formulation used in a “classic” two-dimensional model. The resulting hybrid “two-dimensional/three-dimensional model” enables changes in current profile due to variations in eddy viscosity to he examined independently of those due to changes in bed stress. Also, results from the model are compared with those from a three-dimensional model with bed stress related to bottom current. Computed tidal elevations and surface currents are found to be fairly insensitive to the parameterization of bottom stress. However, tidal current profiles in the near-bed region and maximum bed stress are found to be sensitive to variations in near-bed viscosity and friction coefficient. Although reducing eddy viscosity in the near-bed ...