Seasonal variation of the circulation in the Taiwan Strait

Abstract

The Taiwan Strait is an essentially meridional channel connecting the East and South China Seas. There is often a northward current on the east side and a southward current on the west side. The source water feeding the eastern boundary current is South China Sea Water in summer and Kuroshio Branch Water in other seasons. The current on the west side carries colder and fresher China Coastal Water southward. Both currents are modulated by the annual cycle of monsoon wind forcing, which reinforces the northward current in summer but southward current in other seasons. Further, both currents are partially impeded by a bottom ridge (Changyun Rise) in the middle reaches of the strait. The combination of monsoon and topography forcing leads to the winter blocking of northward current, spring renewal of northward intrusion, minimal blocking of northward intrusion in summer, and fall emergence of China Coastal Current. A recent hydrographic data set, satellite images and a numerical model lend support to these findings.