A Study of Circulation, Turbulence, and Tidal Stream Resources in the Taiwan Strait

Abstract

The 3-D Princeton Ocean Model with tidal forcing supplied by a 2-D barotropic model was used to examine the time-depth variability and features of tidal current, turbulence, and power of tidal stream energy in the Taiwan Strait (TS). A number of potential tidal stream sites for the kinetic energy conversion were identified. Numerical simulations showed that semidiurnal tidal currents are predominant in the TS, with along-channel maximum amplitude reaching 1.3 m s–1. The modeling revealed multicore eddy structures generated by the ebb and flood flows over the Chang-Yuen Rise (CYR). The eddy structures were found to contain filaments with different vorticities, positions, and signs, which depend on the phase of the tide. The maximum of absolute relative vorticity was estimated to reach 100 rad/week. During the flood-ebb cycle, the turbulence exhibited symmetry over the CYR and in the Peng-Hu Channel (PHC), while in the cross-slope direction south from the CYR it was asymmetrical, changing from ebb-dominant to flood-dominant. The maximum values of eddy diffusivity within the bottom boundary layer ranged from ∼10–3 to 10–2 m2 s–1. A numerical simulation revealed that, in the PHC, bottom shear turbulence on the flood is suppressed by strong stratification due to the inflow of dense water from the South China Sea. An assessment of power density revealed several potentially attractive sites for the installation of tidal turbines in the vicinity and over the CYR. Tidal currents at these sites are characterized by insignificant flood/ebb asymmetry and the magnitude of power density reached 100 Wm–2. The most promising site for tidal energy converter installations was identified in the northern extremity of the PHC, where the magnitude of power density reached 300 Wm–2.