Numerical Simulation of Blue Tides in the Head of Osaka Bay

Abstract

Blue tide events were observed four times in the head of Osaka Bay from July to September, 2005. Strong north wind from the land blew continuously in each event, and the sudden fall of the water temperature of the surface layer and DO of the middle layer were observed at the same time. The upwelling of anoxic water was regarded as the dominant factor of the blue tide events. To discuss these processes, we carried out now cast simulation by using the three-dimensional numerical model by focusing on DO. As a result, the blue tide events and the difference of scales among the events were reproduced. The difference was attributed not only to the strength and weakness of north wind but also to the duration and a condition of the thermal stratification.