Abstract
The time variation in the path pattern of the Kuroshio was studied by use of nine observed distances of the main Kuroshio axis from the Japanese coast. The observed distances of the main Kuroshio axis from 1975 to 1995 were estimated from the Prompt Report of Oceanographic Conditions published by the Hydrographic Department of the Maritime Safety Agency of Japan. The large meander path that formed in 1975 had relatively large distance from the coast in the upstream area from off Ashizuri-misaki to off Daioh-zaki, whereas five large meander paths formed after 1981 commonly had large distances in the downstream area from off Omae-zaki to off Inubou-zaki. The mean distance during the large meander path formed in 1975 passes the gate area over the Izu Ridge between Miyake-zima and Hachijou-jima, whereas those formed after 1980 located at shallow region over the Izu Ridge, south of the gate area. It is suggested that relatively short periods of the large meander paths formed after 1980 are due to fast spin-down by the topographic effect of the Izu Ridge south of the gate area. It was shown from the sea level difference south of Kyushu that the large volume transport of the southern inflow of the Kuroshio from south of Kyushu to the Shikoku Basin precedes the large distance of the Kuroshio off Toi-misaki to Muroto-misaki and small distance off Omae-zaki to Irow-zaki. In contrast, the large volume transport of northern inflow precedes the larger distance off Omae-zaki to Nojima-zaki and small difference off Toi-misaki to Shiono-misaki. No significant correlation is found between the volume transport of the Kuroshio south of Kyushu and the offshore distance off Inubou-zaki.
