鹿児島湾の海水循環

摘要

Kagoshima bay is composed of northern and southern basins. The depth of the basins ex-ceeds 200m, respectively. These basins are connected by a narrow and shallow channel called Nishi-Sakurajima channel. The depth of this channel is about 40m. There is a sill between the southern basinand the open sea. The depth of the sill is 70m. In this paper, the horizontal and vertical circulations andthe sea water exchange between Kagoshima bay and the open sea are described.On the east side of the southern basin, the temperature and salinity in the upper layer are higher than onthe west side. It is found out that the sea water from the open sea flows northward along the east side ofthe southern basin, then form an anti-clockwise horizontal circulation.In winter, the sea water in the northern and the southern basin becomes homogeneous by convection. Butat the bottom layer of the northern basin, there is a water mass subducted from Nishi-sakurajima channel.This water mass is formed by shallow waters in both basins. Water masses occupy the northern basinexcept the shallow layer, which are formed in Nishi-sakurajima channel in March and April.In the mouth of the bay, the inflow occurs in the upper layer and the outflow occurs in the lower layer inFebruary. However in June, the outflow occurs in the upper layer and the inflow occurs in the lower layer.