A Continuous Mapping of Tidal Current Structures in the Kanmon Strait

Abstract

Tidal current structures at the Hayatomono-Seto of the Kanmon Strait are mapped continuously during March 17 to 20, 2003, including a spring tide, by the eight coastal acoustic tomography (CAT) systems distributed on both the sides of the strait. Detailed structures of strong tidal currents and their associated vortices are well reconstructed by the inverse analysis of travel-time difference data obtained from the reciprocal sound transmission between the paired CAT systems located at both sides of the strait mainly. The results are well compared to the shipboard acoustic Doppler current profiler (ADCP) data at the correlation rate of 0.84/0.82 and the RMS difference of 0.47/0.48 ms−1 for the east-west/north-south current after the selection of good data. During the observation period, the maximum hourly mean volume transport for the upper 7 m layer across the strait reached 13,314 m3 s−1 for the eastward and 5,547 m3 s−1 for the westward. The daily mean transport is directed to the eastward and estimated 1,470 m3 s−1 and 2,140 m3 s−1 for March 18 and 19, respectively, when a spring tide occurs.