Study on the variability with periods from months to years in the deep ocean

• Project/Area Number: 24540468
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Meteorology/Physical oceanography/Hydrology
• Research Institution: The University of Tokyo
• Principal Investigator: FUJIO Shinzou 東京大学, 大気海洋研究所, 准教授 (00242173)
• Project Period (FY): 2012-04-01 – 2015-03-31
• Project Status: Completed (Fiscal Year 2014)
• Budget Amount: ¥4,160,000 (Direct Cost: ¥3,200,000、Indirect Cost: ¥960,000); Fiscal Year 2014: ¥1,040,000 (Direct Cost: ¥800,000、Indirect Cost: ¥240,000); Fiscal Year 2013: ¥2,080,000 (Direct Cost: ¥1,600,000、Indirect Cost: ¥480,000); Fiscal Year 2012: ¥1,040,000 (Direct Cost: ¥800,000、Indirect Cost: ¥240,000)
• Keywords: 深層循環 / 係留流速計 / 流速変動 / 海洋深層流 / 長期測流 / 深層変動流 / 海溝 / 数値シミュレーション

Outline of Final Research Achievements

Data analysis was performed on 2000-day-long time series of the deep current velocity to the east of Tohoku, Japan. Variability is dominant widely at the periods from three to six months, and weak at the annual and longer periods. As a result, year-long mean velocities are rather constant. Near the Japan Trench, the phase propagation is clearly identified along it, and above the abyssal plain, it seems westward. A good agreement of energy spectra with a two-layer model simulation driven only by surface wind suggests the variability is caused mainly by wind.

Research Products

• [Journal Article] Recent sediment dynamics in hadal trenches: evidence for the influence of higher-frequency (tidal, near-inertial) fluid dynamics (2014)
  • Author(s): Turnewitsch, R., Falahat, S., Stehiko, J., Oguri, K., Glud, R.N., Middelboe, M., Kitazato, H., Wenzhoefer, F., Ando, K., Fujio, S., Yanagimoto, D.
  • Journal Title: Deep-sea research I Volume: 印刷中 Pages: 125-138
  • DOI: 10.1016/j.dsr.2014.05.005
  • Peer Reviewed / Open Access
• [Journal Article] 深層循環 ―アルゴの下を測る― (2013)
  • Author(s): 藤尾伸三・柳本大吾・安藤広二郎
  • Journal Title: 月刊海洋 Volume: 45 Pages: 50-56
• [Journal Article] Pathway and variability of deep circulation around 40°N in the northwest Pacific Ocean (2013)
  • Author(s): Ando K., Kawabe M., Yanagimoto D., and Fujio S.
  • Journal Title: Journal of Oceanography Volume: 69 Issue: 2 Pages: 159-174
  • DOI: 10.1007/s10872-012-0164-2
  • Peer Reviewed
• [Presentation] Mesoscale variability of deep currents in the Northwest Pacific Basin (2014)
  • Author(s): Miyamoto, M., Oka, E., Yanagimoto, D., Fujio, S., Kurogi, M., and Hasumi, H.
  • Organizer: American Geophysical Union, Fall Meeting
  • Place of Presentation: San Fransisco, U.S.A.
  • Year and Date: 2014-12-15 – 2014-12-19
• [Presentation] 深層平均流についての観測とFRA-JCOPE2再解析データとの比較 (2014)
  • Author(s): 西垣肇・加賀田雅士・藤尾伸三・柳本大吾・鍛治胡桃
  • Organizer: 日本海洋学会
  • Place of Presentation: 東京海洋大学、東京
• [Presentation] Latitudinal Variation of the eddy diffusivity at the surface layer in the North Pacific Ocean (2014)
  • Author(s): Haruka Nakano, Yui Kurono, Shinzo Fujio, and Jiro Yoshida
  • Organizer: Ocean Sciences Meeting
  • Place of Presentation: Honolulu, Hawaii, USA
• [Presentation] 西部北太平洋における鉛直渦拡散係数のパラメタリゼーション (2013)
  • Author(s): 中野知香・藤尾伸三・吉田次郎
  • Organizer: 日本海洋学会
  • Place of Presentation: 北海道大学、北海道
• [Presentation] Pathway and variability of deep circulation current in the Northwest Pacific (2013)
  • Author(s): 安藤広二郎・川辺正樹・柳本大吾・藤尾伸三
  • Organizer: 北方圏国際シンポジウム
  • Place of Presentation: 北海道紋別市
• [Presentation] 日本東方北緯40度を流れる深層循環流の鉛直構造と輸送量変動 (2013)
  • Author(s): 安藤広二郎・藤尾伸三・柳本大吾
  • Organizer: 日本海洋学会
  • Place of Presentation: 東京都品川区