Abstract
Near-surface current measurements by two high-frequency oceanic surface radars of the Frequency Modulated Interrupted Continuous Wave (FMICW) type were carried out during December 2000-March 2001 in order to investigate the characteristics of short-period fluctuations of surface circulation in Sagami Bay induced by Kuroshio wann water (KWW) intrusions. When the KWW intrudes into the bay through Ooshima west channel (OWC), cyclonic and anti-cyclonic circulations are generated in the central part of the bay and in the lee of Ooshima Island, respectively, as suggested by previous studies based on mooring and drifting buoy observations (e.g. Taira and Teramoto, 1986; Iwata and Malsuyama, 1989). These two circulations fluctuate with periods of about 811 days. When the KWW strongly intrudes into the bay from OWC, cyclonic and anti-cyclonic circulations become large and the centers of the circulations move south west ward and northeastward, respectively. In addition, warm water intrudes into the mouth of Tokyo Bay and a coastal front appears at the bay month. Statistical analyses, including standard Empirical Orthogonal Function (EOF) analysis, and satellite infrared images of the Knroshio indicate that the dominant fluctuation of the circulation is caused by temporal change in strength of the KWW intrusion due to small-scale (10-15 km) offshore-inshore movement of the Kuroshio front. This movement is thought to, be due to the Ekman transport induced by a southwestward-northeastward wind.
