Jan¹, Sen, and Shenn-Yu Chao²

¹Institute of Physical Oceanography, National Sun Yat-Sen University, 70 Lien-Hai Road, Kaohsiung 80424, Taiwan, R.O.C., Tel: 886-7-5252000 Ext. 5353, Fax: 886-7-5255359, Email: senjan@mail.nsysu.edu.tw and ²Horn Point Laboratory, University of Maryland Center for Environmental Science, P.O. Box 0775, Cambridge, Maryland 21613-0775, U.S.A.

Seasonal variation of volume transport in the major inflow region of the Taiwan Strait: The Penghu Channel

Eight cruises of current measurements along a zonal transect (~31.84 km) across the major inflow region of the Taiwan Strait, the Penghu Channel, were carried out using the shipboard Acoustic Doppler Current Profiler (ADCP) during 1999-2001. On each cruise, the measurement was repeated twice along the transect with a time lag of 6 hours and 12 minutes, and the repeated data were averaged to eliminate the dominant semidiurnal tidal currents. Velocities, after removing semidiurnal tides, suggest that there is a strong northward flow in the channel, with a speed of about 100 cm/s in the upper 50 m in summer. The northward flow becomes much weaker in winter. The calculated throughflow transports vary seasonally and are correlated with the change of the East Asia monsoon. The estimated transport is around 0 during the peak northeast monsoon in winter, increases from 0.5 to 1 Sv (1 Sv = 10⁶ m³/s) as the northeast monsoon weakens in spring, peaks to 1.5 Sv at the end of southwest monsoon in summer, and decreases rapidly from 1.5 to 0 Sv when the northeast monsoon intensifies in fall. The error, mostly induced by unfiltered diurnal tidal currents, is estimated to be ± 0.20 Sv in the transport calculation.