SEASONAL VARIATIONS IN TEMPERATURE, SALINITY AND DISSOLVED OXYGEN IN THE ENCLOSED AREA AT THE HEAD OF OSAKA BAY, JAPAN

摘要

In the head of Osaka Bay, it has been well known that the north wind causes upwelling the water at the bottom layer. It makes a contribution to the disappearance of the anoxic water, and to produce the water upwelling in the ANA-Port. The direction of the prevailing wind in summer is southwest, and the anoxic water remains stably over the sea bottom. However, when the northerly wind blows induced by meteorological disturbance, the lower anoxic water is drifted toward the upper layer of the north shore, which results in blue tide appearance for supplementing the upper water transported to south. If the duration time of meteorological disturbances is short, namely one to three days, no vertical mixing occurs between the upper and lower water. When the wind blowing was strong, the anoxic water once disappeared; however it was observed to return to the original shape on the next observation after one week. The north wind, which is effective to decrease the anoxic water over the whole area of the head of the bay, does not have a significant improvement of the anoxic water in the port.