A numerical experiment on ocean circulations forced by seasonal winds in Suruga Bay

Abstract

We investigate influence of the seasonal variation in the wind field on water circulation in Suruga Bay by using a wind data set and a numerical ocean model. Counterclockwise vorticity is supplied around the bay mouth from the atmosphere into the ocean in January (winter) and April (spring), whereas clockwise vorticity is supplied in July (summer) and October (autumn). Corresponding to the change in the wind field, a counterclockwise circulation is generated at the sea surface around the bay mouth in January and April, whereas a clockwise circulation in July and October. Moreover, one or two weak circulations are generated to the north of the circulation. These circulations, which are quasi-geostrophic and strongly influenced by land and ocean bottom topography, are generated without effect of the Kuroshio current. Quasi-stagnant and convergent regions tend to appear in the surface layer in the eastern part of the bay, except for autumn. There is a possibility that the wind-driven circulations may play an important role in transport of floating materials, such as seagrass, from in and around the bay to the eastern part of the bay, where a large amount of seagrass has been observed both on the sea surface and floor