An Assessment of Influence of Open Boundary Forcing and Bottom Friction on the Tidal Elevation Along West Coast of Korea

Approaching the West Coast of Korea (WCK), the tidal amplitudes vary from 4 to 8 meters, and the speed of the tidal current may increase to more than 1.56 m/s near the coasts. Along with strong tidal currents, the WCK is surrounded by lots of islands including extremely irregular and indented coastlines, therefore the tidal propagation and shoaling processes on the shore in this broad flat region are very complicated and sensitive to the variation of open boundary condition and bottom friction coefficients.

Applying different open source numerical models; FVCOM and TELEMAC, with a higher unstructured grid resolution, this study is based on the analysis of numerical results to suggest a practical approach to accurately simulate tidal elevations from major constituents around the WCK. To obtain an accurate tidal forcing at open boundaries, three well-known tidal models; two global assimilated tidal models (NAO.99b and FES2014) and one regional tidal model (NAO.99Jb), have been applied to interpolate the offshore tidal boundary conditions. Furthermore, in order to evaluate the dependence of the tidal elevation around the WCK on the open boundary forcing and the sea bed roughness, a sensitivity analysis has been implemented. In comparison between the observations and simulation results, it shows that the numerical result is more sensitive dependence on the bottom roughness than open boundary conditions.