Numerical computation of tidal currents in the eastern and southern parts of the East China Sea

Numerical simulation on diurnal and semidiurnal tidal currents is made for the eastern and southern parts of the East China Sea bounded by the Tsushima, islands of Kyushu and Ryukyu in the east and extending to the central Taiwan Strait in the south. The numerical computation shows that the rapid variation in the seabed topography near the Okinawa Trough may cause computational instability and this instability can be removed by setting a suitable lateral eddy viscosity. The computed results are in good agreement with the observations and indicate that the tidal currents in the greater part of the area studied rotate clockwise. An M₂ current-amphidromic point exists in the southern part of the Korea Strait and another one appears in the west of Okinawa with less certainty. K₁ and M₂ cotidal charts based on the observed and computed tidal currents in the sea and the observed tides on the coast are also given.