Field Observation on the Horizontal Velocity Profile of Wind-driven Currents with Secondary Circulations

Abstract

Field observation on the horizontal velocity profile of wind-driven currents with secondary circulations was conducted in the lake of Shinji by using the web camera and the horizontal ADCP, H-ADCP, in order to propose the convenient method of Langmuir observation and to investigate the horizontal profile of wind-driven currents and the occurrence frequency of secondary circulations. Observation results by using the web camera shows the formation of surface streaks when the west wind is strong. H-ADCP was set across the surface streaks. Observation results by using H-ADCP shows the horizontally periodic profiles of wind-driven currents when the west wind is strong. The FFT analysis shows that fourier coefficients and the predominant frequency increase immediately with the increase of wind velocity. It shows the rapid response of periodic profile to the wind velocity.