TERRAPUB Journal of Oceanography

Journal of Oceanography, Vol. 58 (No. 6), pp. 837-850, 2001

Transition of Tidal Waves from the East to South China Seas over the Taiwan Strait: Influence of the Abrupt Step in the Topography

Sen Jan1*, Ching-Sheng Chern2 and Joe Wang2

1Institute of Physical Oceanography, National Sun Yat-Sen University, 70 Lien-Hai Road, Kaohsiung 80424, Taiwan, Republic of China
2Institute of Oceanography, National Taiwan University, P.O. Box 23-13, Taipei 10617, Taiwan, Republic of China

(Received 1 June 2001; in revised form 22 March 2002; accepted 5 April 2002)

Abstract: Observations of tidal waves between the East and South China Seas (ECS and SCS) over the Taiwan Strait (TS) suggest that the diurnal tides simply appear as one southward-propagating wave from the ECS to the SCS through the TS. The semidiurnal tides, however, behave differently in that they appear as a southward-propagating Kelvin wave in the western TS and a nearly standing wave in the eastern TS, and then diminish rapidly over the shallow shoal in the southern TS. A smaller-domain model, with sea-level boundary conditions derived from a larger-domain tidal model, was first used to simulate tides in the TS to an overall percentage of accuracy of about 90%. Subsequent numerical experiments and theoretical analysis revealed that the southward-propagating semidiurnal tides to be impeded and then reflected as they arrive at an abrupt, deepened step in the topography of the southern TS. This reflection enhances the amplitudes of the incident semidiurnal tides and contributes to the formation of a nearly standing wave in the eastern TS. The southward-propagating diurnal tides in the TS are connected by the diurnal tides in the northern SCS when the amplitudes of the two tide systems are comparable and their phases nearly equal at the step.

*Corresponding author E-mail: senjan@mail.nsysu.edu.tw

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