Direct measurements of mid-depth circulation in the Shikoku basin by tracking SOFAR floats

Keisuke Taira, Shoji Kitagawa, Katsuto Uehara, Hiroshi Ichikawa, Hiroyuki Hachiya, Toshihiko Teramoto

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9 Citations (Scopus)


Mid-depth circulation of the Shikoku Basin was measured by tracking four SOFAR floats drifting at the 1,500 m layer. Two floats were released on 17 April 1988 at 30°N, 135°59′E and tracked for 433 days. Another two were released on 3 November 1988 at 29°52′N and 133°25′E, and tracked for 234 days. Two floats flowed clockwise around the Shikoku Warm Water Mass with a diameter of 400 km centered at 31°N and 136°E and a mean drift speed of 4.5 cm sec-1. One of the floats showed about ten counterclockwise rotations with a period of about 8 days and a maximum speed of 80 cm sec-1 in the sea area west to the Izu Ridge. In the east to Kyushu, a southward flow was observed under the northward flowing Kuroshio. The southward flow of 4 cm sec-1 drift speed was considered to be a part of the counterclockwise circulation at deep layers along the perimeter of the Shikoku Basin. One float remained for 234 days in a limited area of 100 km by 150 km in the western part of the basin.

Original languageEnglish
Pages (from-to)296-306
Number of pages11
JournalJournal of the Oceanographical Society of Japan
Issue number6
Publication statusPublished - Dec 1990
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Environmental Science(all)
  • Soil Science
  • Engineering(all)
  • Earth-Surface Processes
  • Earth and Planetary Sciences(all)


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