Journal of Oceanography

, Volume 46, Issue 6, pp 296–306 | Cite as

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
Article

Abstract

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.

Keywords

Sound Speed Mooring Line Glass Ball Kuroshio Path Drift Speed 

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Copyright information

© Oceanographical Society of Japan 1989

Authors and Affiliations

  • Keisuke Taira
    • 1
  • Shoji Kitagawa
    • 1
  • Katsuto Uehara
    • 1
  • Hiroshi Ichikawa
    • 2
  • Hiroyuki Hachiya
    • 3
  • Toshihiko Teramoto
    • 4
  1. 1.Ocean Research InstituteUniversity of TokyoTokyoJapan
  2. 2.Faculty of FisheriesKagoshima UniversityKagoshimaJapan
  3. 3.Research Institute for Precision MechanicsTokyo Institute of TechnologyYokohamaJapan
  4. 4.Faculty of ScienceKanagawa UniversityHiratsukaJapan

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