Study on the Characteristics of Surface Layer’s Currents around the Mouth of Isahaya Bay

This study deals with the field observations on surface layer’s currents by means of Digital Beam Forming marine radar (Its abbreviation is DBF ocean radar.), Acoustic Doppler Current Profilers (Its abbreviation is ADCP.) and floating buoys in order to realize the flow characteristic in the center of Ariake Sound. As a result, it is obvious that tidal current along the north coastline of the Shimabara Peninsula is dominant during flood tide and that there is outflow into Ariake Sound from Isahaya Bay near Takezaki Island in the best part of one tidal cycle at spring tide. Furthermore, it is found out that the maximum current velocity of flood tide measured using DBF ocean radar branches off to both Isahaya Bay and the head of Ariake Sound significantly. It is also obvious that the flow velocity vector observed by DBF ocean radar accords with the one obtained by ADCP. That is to say, DBF ocean radar is one of the powerful remote sensing tools to measure surface layer’s currents from the land widely and continuously without being affected by weather conditions.Nagasaki University Major Research Project: Restoration of Marine Environment and Resources in East Asi