The Kyucho Current in Sagami Bay and at the Mouth of Tokyo Bay Induced by the Eastward Propagation of Small Meanders of the Kuroshio

Abstract

Temperature, current and sea level data obtained in and around Sagami Bay and the mouth of Tokyo Bay were analyzed to clarify the generation processes and trigger phenomena of the Kyucho (stormy current) related with the Kuroshio. The Kyucho occurred at the end of May in 1998 and was caused by warm water intrusion originating from the Kuroshio into Sagami Bay through Oshima West Channel. The warm water was considered to separate at Zenith, a shallow region at the west of Izu Ridge. From there it moved eastward propagated by a small meander of the Kuroshio, and it then progressed northward along the west side of Zenith, Izu Ridge and Islands. From the analysis of the sea level data from1993 to1999, most of the Kyucho related with the Kuroshio occurred after a sea level rise at Kozu and Miyake Islands. Furthermore sea level differences between Minami-izu and Ito were found to show significant peaks before the occurrence of the Kyucho.