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The Role of Double Diffusive Convection in the Mixing Process in the ocean

Research Project

Project/Area Number 16340137
Research Category

Grant-in-Aid for Scientific Research (B)

Allocation TypeSingle-year Grants
Section一般
Research Field Meteorology/Physical oceanography/Hydrology
Research InstitutionTOKYO UNIVERSITY OF MARINE SCIENCE AND TECHNOLOGY

Principal Investigator

YOSHIDA Jiro  Tokyo University of Marine Science and Technology, Department of Ocean Sciences, Professor, 海洋科学部, 教授 (30174931)

Co-Investigator(Kenkyū-buntansha) NAGASHIMA Hideki  Tokyo University of Marine Science and Technology, Department of Ocean Sciences, Professor, 海洋科学部, 教授 (10087570)
KITADE Yujiro  Tokyo University of Marine Science and Technology, Department of Ocean Sciences, Associate Professor, 海洋科学部, 助教授 (50281001)
Project Period (FY) 2004 – 2005
Project Status Completed (Fiscal Year 2005)
Budget Amount *help
¥16,300,000 (Direct Cost: ¥16,300,000)
Fiscal Year 2005: ¥3,700,000 (Direct Cost: ¥3,700,000)
Fiscal Year 2004: ¥12,600,000 (Direct Cost: ¥12,600,000)
Keywordsturbulent dissipation / Turbomap / double diffusive convection / interleaving / density ratio / step structure / WOCE data set / 1 Munk / ソルトフィンガー / 北太平洋中層水 / 回帰線水 / 乱流構造 / ENSOイベント
Research Abstract

1.In the area of the western-north Pacific ocean, detailed observations of temperature, salinity and turbulent dissipation using CTD and Turbomap in 2004 and 2005 showed enhanced mixing processes might be due to double diffusive convection occurred in the area where typical water masses were contacted. Especially, off the Sanriku coast, double diffusive interleaving processes having high turbulent dissipation rate at the interfaces were observed from Thrbomap yo-yo observation.
2.Simple one-dimensional temperature-salinity diffusion model parameterizing the vertical eddy diffusivities changing with density ratio were employed to investigate the development of vertical temperature and salinity profiles typically observed in the north Atlantic. We first successfully showed the formation of step structure caused by the convergence of density flux due to double diffusive convection. These steps having small vertical scale at first, merges to increase their thickness, and finally approaches smooth temperature and salinity profiles with the density ratio value 2. This final state is coincided with the observation.
3.Mapping of density ratio in the world ocean from WOCE data set has been continued. In the course of this study, vertical eddy diffusivities are estimated through the density flux ratio due to double diffusive convection. We obtained 1 Munk (10^<-4>m^2/s) in the whole Atlantic Ocean and in the area around Antarctic Circumpolar Current. But, in the Pacific Ocean, the value was 10^<-6>m^2/s〜l0^<-5>m^2/s at most. These latter values are not sufficient to maintain the permanent thermocline, but the effect of double diffusive convection is not negligible for this process.

Report

(3 results)
  • 2005 Annual Research Report   Final Research Report Summary
  • 2004 Annual Research Report
  • Research Products

    (6 results)

All 2005 2004 Other

All Journal Article (6 results)

  • [Journal Article] Possible Density Change of the Origin of North Pacific Intermediate Water Due to Double Diffusion in the Mixed Water Region.2005

    • Author(s)
      R.Inoue, J.Yoshida
    • Journal Title

      Journal of Oceanography 61

      Pages: 871-883

    • NAID

      40006831455

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      2005 Annual Research Report 2005 Final Research Report Summary
  • [Journal Article] Deep western boundary current along the eastern slope of the Kerguelen Plateau in the Southern Ocean.2005

    • Author(s)
      Narumi Y., Y.Kawamura, T.Kusaka, Y, Kitade, H.Nagashima
    • Journal Title

      La mer 43(1-2)

      Pages: 49-60

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      2005 Final Research Report Summary
  • [Journal Article] Possible Density Change of the Origin of North Pacific Intermediate Water Due to Double Diffusion in the Mixed Water Region.2005

    • Author(s)
      RIlnoue, J.Yoshida
    • Journal Title

      Journal of Oceanography 61

      Pages: 871-883

    • NAID

      40006831455

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      2005 Final Research Report Summary
  • [Journal Article] Deep western boundary current along the eastern slope of the Kerguelen Plateau in the Southern Ocean.2005

    • Author(s)
      Narurmi Y, Y.Kawamura, T.Kusaka, Y.Kitade, H.Nagashima
    • Journal Title

      La mer 43(1-2)

      Pages: 49-60

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      2005 Final Research Report Summary
  • [Journal Article] 相模湾中央部で観測された内部潮汐の鉛直構造と間欠性2004

    • Author(s)
      北出裕二郎他
    • Journal Title

      海の研究 13・5

      Pages: 461-474

    • NAID

      130004387673

    • Related Report
      2004 Annual Research Report
  • [Journal Article] Possible density change of the origin of North Pacific Intermediate Water due to double diffusion in the Mixed Water Region

    • Author(s)
      Ryuichiro Inoue, Jiro Yoshida
    • Journal Title

      Journal of Oceanography (受理)

    • NAID

      40006831455

    • Related Report
      2004 Annual Research Report

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Published: 2004-04-01   Modified: 2016-04-21  

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