Study on characteristics of tidal dynamics and vortex in Zhoushan Archipelago sea area

Abstract

Numerical modelling is used to study the characteristics and mechanisms of tidal dynamics and vortex in Zhoushan Archipelago sea area. Results show that amplitudes and current speeds of the semidiurnal tides decrease significantly when passing through the islands. Conversion of tidal energy, archipelago topography and formation of shallow-water tides are important reasons for the evolution of tidal waves. The ebb tide has a longer duration in the archipelago sea area, particularly in narrow channels. The M2-M4 constituents play a major role in tidal asymmetry. The flow paths of tidal currents change much, causing the high speed flooding/ebbing near the north/south bank. The tidal vortex is mainly distributed on both sides of and behind the islands, which is related to the shape of islands and the flow velocity. Referring to the current directions, positive/negative vorticity generally appears on the right/left side of the islands.