Coastal Current Observation in the Area of Abrupt Topographic Change with DBF Ocean Radar

A DBF ocean radar can detect the surface current pattern every 15 minutes. The tidal current and the residual current were investigated through the continuous observation of the DBF (digital beam forming) radar in the middle-west area of Ariake Bay in autumn 2005. For the validation of the surface current data by the DBF ocean radar the ship-board ADCP measurements were also conducted at spring tide. As the result of the comparison of both surface current data, the correlation coefficient and the standard error of the current speed are 0.89 and 7.23cm/s, and those of the current direction are 0.92 and 35.89 degree. The harmonic analysis of the long-term data by the DBF ocean radar clarifies the spatial pattern of the principal tides and the residual currents. The residual currents in 15days flow south to southeastward caused mainly by the tidal residual currents due to the topographic asymmetry.