On Horizontal Circulations in a Mixed Layer of the Lake Ogawara

Abstract

Wind induced currents in Lake Ogawara is discussed being based on field experimental data obtained in autumn of 2006. In the experiment, three ADCPs were set on the bottom of the north, the center and the south water areas for two months. The data showed a periodic appearance of intense shear layer in the metalimnion that seemed to be generated by internal seiche. Measurement from three boats equipped with ADCP was conducted for three days in the same water areas under predominant wind direction of west and south. The data suggested the existence of rather stable horizontal currents in the surface mixed layer. These facts suggest that substances entrained from anaerobic hypolimnion by the shear motion are carried by the stable horizontal current in the surface layer to develop uneven condition of water environment.