Direct observation of mixing and diffusion in the Southern Ocean

• Project/Area Number: 24540475
• 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: Japan Agency for Marine-Earth Science and Technology
• Principal Investigator: KATSUMATA Katsuro 国立研究開発法人海洋研究開発機構, 地球環境観測研究開発センター, グループリーダー代理 (80450774)
• Project Period (FY): 2012-04-01 – 2016-03-31
• Project Status: Completed (Fiscal Year 2015)
• Budget Amount: ¥5,200,000 (Direct Cost: ¥4,000,000、Indirect Cost: ¥1,200,000); Fiscal Year 2014: ¥260,000 (Direct Cost: ¥200,000、Indirect Cost: ¥60,000); Fiscal Year 2013: ¥130,000 (Direct Cost: ¥100,000、Indirect Cost: ¥30,000); Fiscal Year 2012: ¥4,810,000 (Direct Cost: ¥3,700,000、Indirect Cost: ¥1,110,000)
• Keywords: 南大洋 / 渦 / 渦輸送 / 運動量輸送 / 形状抵抗 / 西岸境界流 / アルゴフロート / 南極中層水 / 鉛直拡散 / 水平拡散 / 南大洋の渦 / 長期変動 / 海洋大循環 / 鉛直混合

Outline of Final Research Achievements

We observed vertical and horizontal mixing and diffusion in the Southern Ocean. Expendable Microstructure Profilers suffered from noise and premature termination possibly due to optical fibre and yielded limited data. Drift and hydrographic data from Argo floats demonstrated spatial distribution of two quantities; horizontal eddy transport in the upper 1000 m and vertical propagation of eastward momentum through the water column carried by eddy topography interaction. For the former, strong poleward transport (spreading of Sub-Antarctic Mode Water and Antarctic Intermediate Water) was found in the South Indian Ocean. For the latter, the momentum transfer is limited to several spots where the Antarctic Circumpolar Current negotiates topographic obstacles despite large spatial scales of momentum input by westerly wind.

Research Products

• [Presentation] アルゴフロートで観測された南大洋の渦 (2016)
  • Author(s): 勝又勝郎
  • Organizer: 日本地球惑星科学連合 2016 年大会
  • Place of Presentation: 幕張メッセ（千葉県千葉市）
  • Year and Date: 2016-05-24
• [Presentation] アルゴフロートで観測された海洋上層 1000 m の渦輸送 (2016)
  • Author(s): 勝又勝郎
  • Organizer: 日本地球惑星科学連合 2016 年大会
  • Place of Presentation: 幕張メッセ（千葉県千葉市）
  • Year and Date: 2016-05-22
• [Presentation] Eddy transport at 1000 m depth estimated by Argo floats (2015)
  • Author(s): Katsuro Katsumata
  • Organizer: GAIC2015: combined Global Ocean Ship-based Hydrographic Investigations Program/Argo/International Ocean Carbon Coordinate Project Conference on physical and biogeochemical
  • Place of Presentation: Radisson Hotel, ゴールウェイ（アイルランド）
  • Year and Date: 2015-09-25
  • Int'l Joint Research
• [Presentation] Eddy form stress in the Southern Ocean at 1000 dbar (2015)
  • Author(s): K. Katsumata
  • Organizer: 26th IUGG General Assembly 2015
  • Place of Presentation: チェコ、プラハ
  • Year and Date: 2015-06-26 – 2015-07-01
• [Presentation] 南大洋の数年から十年規模の変動 (2015)
  • Author(s): 勝又勝郎
  • Organizer: 日本地球惑星科学連合 2015 年大会
  • Place of Presentation: 千葉県千葉市幕張メッセ
  • Year and Date: 2015-05-27
  • Invited
• [Presentation] 南大洋 1000 m 深の渦
  • Author(s): 勝又勝郎
  • Organizer: 日本海洋学会 2014 年春季大会
  • Place of Presentation: 東京都（東京海洋大学）