Abstract
Komatsu et al.(1997) have proposed asymetrical bottom structure, that is “Bottom Roughness, ” as a new method to activate tidal exchange between a semi-enclosed bay and an outer sea. On the other hand, it is expected that vertical mixing is enhanced by the upwelling produced by the Bottom Roughness. The Bottom Roughness have been installed in the Isahaya Bay since September, 2002 as a field test to fix on soft ground peculiar to the Ariake Sea. In this research, in situ observations to measure time series of tidal current and water temperature at fixed points near the installed Bottom Roughness were carried out in order to examine degree of vertical current and vertical mixing. As a result of this research, it becomes clear that the Bottom Roughness can produce the downwelling when the current flows in the forward direction, meanwhile the upwelling is produced by the backward flow.
