Abstract
Bottom frictional dissipation is one of the key mechanisms regulating the tidal movement in the areas surrounding Taiwan Island, China. However, our existing understanding in this field remains incomplete, because the bottom friction coefficient (BFC) of this area is still unclear. Based on the Semiimplicit Cross-scale Hydroscience Integrated System Model (SCHISM) ocean numerical model, three bottom friction parameterization schemes (BFPSs) were compared, namely the Adjoint Data Assimilation (ADA), Manning Depth-dependent Formula (MDF), and Constant. This research finds that the ADA scheme performed best in tidal simulation. The error of elevation is less than 8.48 cm. Based on the simulation results of the ADA scheme, the tidal dynamic characteristics and bottom frictional dissipation surrounding Taiwan Island were systematically analyzed. Results show that the amplitude peaks of the semidiurnal tides are located in the vicinity of 25°N, 119°E. A densely-packed zone of isophase lines and a zero-ellipticity demarcation line were observed at 23.5°N. Regarding the diurnal tides, the amplitudes exhibit an increasing trend from the southeast towards the northwest, and the isophase lines are orthogonal to the coastline. The frictional dissipation rate is generally high within the strait (mean of 3.1×10−3 W/m2). However, it is relatively low in the Penghu Channel (mean of 1.34×10−5 W/m2). Therefore, the tidal energy flux in the strait is concentrated at the northern and southern extremities (mean of 1.5×106 W/m) as well as in the Penghu Channel. Similar correlations between tidal energy flux and bottom frictional dissipation rate are manifested in the eastern, southern, and northern parts of Taiwan Island.