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Seasonal and interannual variations of surface currents in the southern Taiwan Strait to the west of Taiwan Shoals were investigated by using measurements of high frequency (HF) ground wave radars from January 2006 to April 2009. The results demonstrate that surface currents in the water channel to the west of Taiwan Shoals are composed of a significant, seasonally fluctuating component and a relatively stable northward component. Forced by the East Asia monsoon, the annual variation of the surface longshore current is linearly correlated with the longshore wind. Behind the seasonal signal is a stable northward flow with speeds of O (10 cm/s). The observations also show that surface currents in the area are subject to distinct interannual variation, and the southward surface flow was more profound in winter 2007/2008 than in other winters. Observations from bottom-mounted ADCP also indicated that, in that winter, longshore currents in the west side of the Taiwan Strait are very different from the previous winter. The northward flow appeared much weaker, the currents were southward in most layers, and the interannual differences were observed throughout the water column. Hydrographic observations in the same period suggest that the large-scale southward intrusion of the Zhe-Min coastal water is the direct cause of the interannual difference. The enhancement of the East Asian monsoon during the 2007/2008 La Niña event is considered as the main reason for the winter current anomalies in the study area. [ABSTRACT FROM AUTHOR]

Long-term measurements from a pair of High-Frequency radar systems deployed near the coast of southern Fujian Province showed that surface currents in the southwestern Taiwan Strait were composed mainly of the monsoon-driven, seasonal fluctuation of longshore current and a persistent northeastward background flow with speeds around 10 cm/s. Measurements from bottom-moored ADCPs further indicated that below the surface Ekman layer longshore currents also directed to the north all year round. [ABSTRACT FROM AUTHOR]

The Penghu archipelago locates near the Tropic of Cancer, guarding the southern entrance of the Taiwan Strait (TWS). Since the archipelago is usually surrounded by warm waters from the Kuroshio branch and the South China Sea, the marine ecosystem in the waters surrounding the archipelago is mainly tropical. However, this area may be invaded by cold water, which can cause serious ecological disasters. Among the few rare events ever documented, the cold event in early 2008 represented a typical case in this regard. In this paper, we investigated this event using in situ measurements and remote sensing data. Our analyses show that during the destructive snow and ice storm of early 2008, strong cold winds persisted for ~40 days over the TWS area, with a mean prevailing wind speed of about 15 m/s, and the water temperature in the strait dropped sharply, especially along the mainland coast. On the other side of the strait, the Penghu area experienced extremely low temperatures, leading to a cold event. Note that the time of temperature reduction in Penghu was earlier than the time of temperature reduction in the area farther north along the coast of Taiwan. This indicates that a cross-strait outbreak of the mainland coastal cold-water (MCCW) caused the cold event, and thus triggered the cold disaster. The outbreak resulted from the combined effect of favorable background hydrographic conditions, persistent strong northeasterly, strong mainland coastal current (MCC), and the interaction of current and waves with the bottom topography of the Taiwan Bank (TWB). Remotely generated coastal trapped waves (CTWs) may also play a role. • A rare cold event occurred at Penghu waters in early 2008. • A cross-strait outbreak of the mainland coastal cold-water caused the cold event. • The outbreak resulted from the combined effect of several factors. • Remotely generated coastal trapped waves may also play a role. [ABSTRACT FROM AUTHOR]