Continuous current measurements by using current meters have revealed some characteristics of water current in the northern basin of Lake Biwa. The fundamental mode of the internal wave has a great influence on the current field of offshore zone as well as coastal zone. Especially, the water movement in the deep layer (hypolimnion) is strongly controlled by the internal waves. Internal Poincaré wave is dominant in the offshore zone during the period of thermal stratification. Its period, which depends on the internal radius of deformation, is about 17 hours in May and 12 hours in August. Inertial oscillation is also dominant in the offshore zone, and frequently occurs in the thermocline depth.
The cyclonic gyre is disturbed by the effects of continuous strong wind, i.e., the wind driven current and the internal waves. After the wind falls, however, the gyre is soon restored to the original state. Under the strong wind with the direction perpendicular to the shore line, coastal bottom water is transported offshore.

抄録全体を表示