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1992 Fiscal Year Final Research Report Summary

A study of abyssal circulation based on the expansion in terms of vertical modes incorporating density diffusion

Research Project

Project/Area Number 02640314
Research Category

Grant-in-Aid for General Scientific Research (C)

Allocation TypeSingle-year Grants
Research Field 気象・海洋・陸水学
Research InstitutionKYUSHU UNIVERSITY (1991-1992)
The University of Tokyo (1990)

Principal Investigator

MASUDA Akira  Kyushu University;Research Institute for Applied Mechanics;Professor, 応用力学研究所, 教授 (60091401)

Co-Investigator(Kenkyū-buntansha) UEHARA Katsuto  Kyushu University;Research Institute for Applied Mechanics;Research Associate, 応用力学研究所, 助手 (80223494)
Project Period (FY) 1990 – 1992
KeywordsAbyssal circulation / Density diffusion / Expansion in terms of vertical modes / Deep western boundary layers / Viscous and diffusive regimes / Upwelling and downwelling / Bottom topography
Research Abstract

The purpose of this project is to clarify the basic dynamics of abyssal circulation by expanding the field in terms of vertical modes and investigating the behavior of each mode.Incorporating both vertical and horizontal diffusion of density makes the obtained model comparable directly with ordinary three-dimensional numerical experiments.
In our model,deep western boundary layers can be either in viscous or in diffusive regimes, depending on the stratification and latitudes.Higher modes,for which horizontal diffusion works strongly,tend to have broad diffusive western boundary layers.In the poleward flowing(equator-ward) western boundary layer,deep water upwells(downwells),while the opposite sign of vertical flow is found in the narrow layer adjacent to the western coast.By virtue of density diffusion,deep water can downwell near boundaries and even in interior regions.
The structural change of boundary layers and associated appearance of downwelling were explained well in terms of a new concept of diffusion of(the thickness term of)potential vorticity, which applies as well to surface layers of stratified oceans.
In an extended model,effects of isolated bottom topography on abyssal circulation were investigated. In particular,by including dissipative terms,we determined the field inside the geostophic island,which had been beyond the scope the characteristic method.
A direct method was developed to solve higher modes efficiently.It was used to investigate the vertical structure of ocean circulation.

  • Research Products

    (13 results)

All Other

All Publications (13 results)

  • [Publications] 増田 章: "海の大循環" パリティ. 6. 20-29 (1991)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Masuda,A.and K.Uehara: "A reduced-gravity model of the abyssal circulation with Newtonian cooling and horizontal diffusion." Deep-Sea Research. 39. 1453-1479 (1992)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] 増田 章: "孤立した海底地形周辺の深層循環" 九州大学応用力学研究所所報. 74. 23-44 (1992)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] 上原 克人: "深層熱塩循環の研究に用いる定常線型浅水方程式系の直接解法" 九州大学応用力学研究所所報. 74. 59-93 (1992)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Uehara,K.: "Density field along 12°N and 13°N in the Philippine Sea." The Deep Western North Pacific. (1993)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Masuda,A.: "The completeneness theorem for Rossby normal modes of a sta-bly stratified flat ocean with an arbitrary form of side boundary." Quarterly of Applied Mathematics. (1993)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Masuda,A: "General Circulation of the Ocean" Parity. 6. 20-29 (1991)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Masuda,A: "Oceanography and Mathematics" Umi to Sora. 67. 163-175 (1991)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Masuda,A: "A reduced-gravity model of the abyssal circulation with Newtonian cooling and horizontal diffusion" Deep-Sea Research. 39. 1453-1479 (1992)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Masuda,A: "On the abyssal circulation around isolated bottom features based on a reduced-gravity model incorporating vertical and horizontal diffusion of density" Bulletin of Research Institute for Applied Mechanics. 74. 23-44 (1992)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Uehara,K: "Direct solution for the system of steady linear shallow water equations used for the thermohaline circulation in the ocean" Bulletin of Research Institute for Applied Mechanics. 74. 59-93 (1992)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Uehara,K: "Density field along 12゚N and 13゚N in the Philippine Sea.in The Deep Western North Pacific edited by T.Teramoto" Elsevier. (1993)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Masuda,A: "The completeness theorem for Rossby normal modes of a stably stratified flat ocean with an arbitrary form of side boundary" Quarterly of Applied Mathematics. (1993)

    • Description
      「研究成果報告書概要(欧文)」より

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Published: 1994-03-24  

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