Synoptic flow structures in the confluence region of the Kuroshio and the Ryukyu Current

In the southeastern region of Kyushu, Japan, the Kuroshio from the East China Sea encounters the Ryukyu Current from the east of the Ryukyu Islands. By analyzing . synoptic sections of water properties and geostrophic velocity in August 2004 and October 2005, we distinguished the waters in the Kuroshio southeast of Kyushu to be. separated into an offshore region and a shallow onshore one. The onshore water is derived from the East China Sea, while the offshore water originates from both the east of Amami-Oshima Island and the interior region of the North Pacific. The water mass transport from the east of Amami-Oshima Island may become equivalent to that of the Kuroshio in the East China Sea as in October 2005. The volume transport-averaged temperature of the Kuroshio southeast of Kyushu is significantly lower than that in the East China Sea because of the confluence with the colder Ryukyu Current east of the Amami-Oshima Island.