Kuroshio Stream path variation and its associated velocity structures south of Shikoku, Japan

Abstract

During 1993‐1995, twelve repeat observations of the Kuroshio south of Shikoku, Japan were carried out for obtaining a vertical velocity section of the upper 300m, using a towed‐type acoustic Doppler current profiler (ADCP). Among the twelve observations, the Kuroshio took the onshore path 9 times and the offshore path 3 times. The cross‐stream velocity distribution around the Kuroshio stream axis is asymmetric (steeper on the onshore side than on the offshore side) for the onshore path while it is symmetric for the offshore one. The core with a maximum velocity is submerged to 100‐200m depths for the onshore case and located at the near surface for the offshore case. In the combined analysis with the Rapid Bulletin of Ocean Conditions, the Kuroshio mainly took an onshore path with stream‐axis positions less than 80km from Cape Ashizuri, but the distance was increased over 150km at the frequency once a year.