Abstract
This paper deals with the seawater exchange caused by density gradient between the outer bay and inner bay using density profile around the bay mouth and velocity profile above the mound. It is revealed that the mechanism of seawater exchange is greatly influenced with the density intrusion depending on the horizontal density gradient. When the density of the outer bay is smaller than the inner bay, the seawater exchange occurs in the upper layer, and cannot be expected in the lower water. But, when the density of the outer bay becomes bigger than the inner bay, for example, after coming typhoon, seawater exchange is accelerated by two types of seawater exchange mechanism. One is intrusion of the outer bay water, the other is out flow due to internal wave (entrainment).
