Effect of Open Boundary Conditions and Bottom Roughness on Tidal Modeling around the West Coast of Korea

Van Thinh Nguyen,Minjae Lee

doi:10.3390/w12061706

Abstract

The aim of this study was to investigate the effect of open boundary conditions and bottom roughness on the tidal elevations around the West Coast of Korea (WCK) using an open-source computational fluids dynamics tool, the TELEMAC model. To obtain a detailed tidal forcing at open boundaries, three well-known assimilated tidal models—the Finite Element Solution (FES2014), the Oregon State University TOPEX/Poseidon Global Inverse Solution Tidal Model (TPXO9.1) and the National Astronomical Observatory of Japan (NAO.99Jb)—have been applied to interpolate the offshore tidal boundary conditions. A number of numerical simulations have been performed for different offshore open boundary conditions, as well as for various uniform and non-uniform bottom roughness coefficients. The numerical results were calibrated against observations to determine the best fit roughness values for different sub-regions within WCK. In order to find out the dependence of the tidal elevation around the WCK on the variations of open boundary forcing, a sensitivity analysis of coastal tide elevation was carried out. Consequently, it showed that the tidal elevation around the WCK was strongly affected by local characteristics, rather than by the offshore open boundary conditions. Eventually, the numerical results can provide better quantitative and qualitative tidal information around the WCK than the data obtained from assimilated tidal models.

Highlights

The Yellow Sea (YS) is located between the mainland of China and the Korean Peninsula, and its depth is about 44 m on average, with a maximum depth of 152 m
We have evaluated the response of coastal tide to open boundary forcing in the West Coast of Korea (WCK), using the sensitivity analysis in the response of coastal tide to open boundary forcing in the WCK, using the sensitivity analysis
The main goal of this study was to use various numerical investigations to figure out the response of coastal tides in the WCK to the open boundary conditions and bottom roughness

Summary

Introduction

The Yellow Sea (YS) is located between the mainland of China and the Korean Peninsula, and its depth is about 44 m on average, with a maximum depth of 152 m. The sea bottom slope gradually rises toward the East China coast and more abruptly toward the Korean Peninsula, and the depth gradually increases from north to south. Southern YS is bounded by the East China Sea (ECS) along a line running northeastward from the mouth of the Changjiang River to the southwestern tip of Korea. On the broad and shallow shelf under the Yellow and the East China Sea (YECS), the flow is dominated by strong semidiurnal M2 tidal currents with the superimposition of semidiurnal S2, diurnal K1 and O1 currents [1,2,3,4]. Approaching the WCK, the tidal amplitudes vary from 4 to 8 m, and the speed of the tidal current may increase to more than 1.56 m/s near the coasts

Objectives

Discussion

Conclusion