Comparison of Bottom Friction Formulations for Single-Constituent Tidal Simulations in Kyunggi Bay

Abstract

This paper investigates the influence of bottom friction on the tidal elevation in Kyunggi Bay, located west of Korea, by comparing the linear, linearized and quadratic bottom friction formulations, deducing an optimal bottom friction coefficient (BFC) for each formulation in single-constituent simulations. Model results are compared with observed tidal amplitudes and phases at 52 locations.The linear friction formulation with an optimal BFC produces the observed tidal elevation satisfactorily for all consitutents. However, the optimal linear BFC in Kyunggi Bay is one order smaller than that used in global tide calculations. The optimal BFC in the linearized formulation for the M2tide is identical to the theoretical value given by Pingree (1983). The optimal linearized BFCs for other constituents are approximately 90% of optimal quadratic BFC for the M2tide alone.Experiments with a range of quadratic BFCs show that the optimal BFCs for single-constituent tide are quite different from constituent by constituent, giving considerably large values of BFC except for the M2tide. The single-constituent simulation shows that the optimal quadratic BFC for S2(K1) only is about 4 (10) times larger than that for M2only. Multi-constituent simulation and single-constituent experiments with the force argument (Bowers et al., 1991) clearly show that the BFC in single-constituent simulations should be increased to incorporate the bulk effects of other constituents.