The research Institute for Applied Mechanics (RIAM), Kyushu University has been conducting long-term acoustic Doppler current profiler (ADCP) observation since February 21, 1997 along the cruise line between Hakata and Pusan to measure the current structure and its time variations at the Tsushima Straits. The Camellia, kitted with a multi-level type ADCP system (VM-BBADCP, 300 kHz, RD Instruments) makes round trips between Hakata and Pusan three times a week at a cruising speed of about 17 kt. The data sampling interval is about 24 seconds and 8 m in depth, from 18 m to 258 m. However the data within the range of 15% of the total depth from the bottom are not of reliable quality (missing data). Since the maximum water depth is about 240 m along the ferry track, the ship velocity relative to the bottom can be measured everywhere through the bottom tracking by the ADCP, implying that the current velocity can be measured relative to the bottom. Constituents of tidal current were decomposed from the observed current data to obtain accurately the mean current without tidal aliasing errors. Using the mean current data, the time variations of the structure and volume transport of the Tsushima current were studied.
展开▼
