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Developing a New Paleosecular Variation Model

Research Project

Project/Area Number 08454117
Research Category

Grant-in-Aid for Scientific Research (B)

Allocation TypeSingle-year Grants
Section一般
Research Field 固体地球物理学
Research InstitutionUniversity of Tokyo

Principal Investigator

KONO Masaru  University of Tokyo, Graduate School of Science, Professor, 大学院理学系研究科, 教授 (20011596)

Project Period (FY) 1996 – 1997
Project Status Completed (Fiscal Year 1997)
Budget Amount *help
¥7,800,000 (Direct Cost: ¥7,800,000)
Fiscal Year 1997: ¥1,900,000 (Direct Cost: ¥1,900,000)
Fiscal Year 1996: ¥5,900,000 (Direct Cost: ¥5,900,000)
KeywordsPaleosecular variation / Taylor expansion / Spherical harmonics / Paleomagnetism / Statistical methods / テーラー展開法 / 地磁気四極子
Research Abstract

Precise measurements of the Earth's magnetic field has been carried out only for less than 200 years since the time of Gauss. Even if we count the sparse measurements of inclination and declination before that, the data covers only several hundred years. On the other hand, the typical time constant of the geomagnetic field is that of the dipole decay (15,000 years). The fact that we cannot hope for a complete description of the geomagnetic field without having observations for several times this time constant can be made clear by the discovery of the magnetic reversals from paleomagnetism. Paleomagnetic data have the characteristics of (1) large errors as well as bad distribution, (2) mostly only directional information, and (3) a few million years may be spanned in a global data set. The head investigator succeeded to formulate the "Taylor Expansion Method" which can overcome these shortcomings of paleomagnetic data by statistical treatment.
Within the period of this project, this method was successfully applied to (1) magnetic field intensity and virtual dipole moment (Kono and Hiroi, EPSL,1996), (2)distributions of inclination and declination (Kono, JGG,1997), (3) the shape of distributions of magnetic field directions and virtual geomagnetic poles (Kono, PEPI,1997). These studies indicate that, apart from the dominant axial dipole term, the (2, 1) harmonics are important in the paleomagnetic field. Further, in the case of nonlinear data such as paleomagnetic directions, it was shown that inversiion of the mean values of the data will not lead to the mean Gauss coefficients. In the case of paleointensity data, these problems are avoided and the mean field can be obtained (Kono, Tanaka, and Tsunakawa, submitted to JGR). Thus far, the forward approach to the paleosecular variation was completed and now is the time for formulating the inversion of paleomagnetic data.

Report

(3 results)
  • 1997 Annual Research Report   Final Research Report Summary
  • 1996 Annual Research Report
  • Research Products

    (24 results)

All Other

All Publications (24 results)

  • [Publications] Tanaka, H., ... M. Kono, and M. O. McWilliams: "Paleomagnetism and chronology of the central Taupo Volcanic Zone, New Zealand" Geophys. J. Int.124. 919-934 (1996)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1997 Final Research Report Summary
  • [Publications] Kono, M. and O. Hiroi: "Paleosecular variation of field intensities and dipole moments" Earth Planet. Sci. Lett.139. 251-262 (1996)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1997 Final Research Report Summary
  • [Publications] Starchenko, S. and M. Kono: "Numerical verification of MEGA in axisymmetric αω-dynamo" Geophys Astrophys. Fluid Dynam.82. 93-123 (1996)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1997 Final Research Report Summary
  • [Publications] Uchiyama, H., M. Kono: "Paleomagnetism of Late Mesozoic rocks from Northeastern China : the role of the Tan-Lu fault in the North China Block" Tectonophysics. 262. 301-319 (1996)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1997 Final Research Report Summary
  • [Publications] Kono, M.: "Paleosecular variation in field directions due to randomly varying Gauss coefficients" J. Geomag. Geoelectr.49. 615-631 (1997)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1997 Final Research Report Summary
  • [Publications] Kono, M.: "Distributions of paleomagnetic directions and poles" Phys. Earth Planet. Inter.103. 313-327 (1997)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1997 Final Research Report Summary
  • [Publications] Tanaka, H., G.M.Turner, B.F.Houghton, T.Tachibana, M.Kono, and M.O.McWilliams: "Paleomagnetism and chronology of the central Taupo Volcanic Zone, New Zealand" Geophys.J.Int.124. 919-934 (1996)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1997 Final Research Report Summary
  • [Publications] Kono, M.and O.Hiroi: "Paleosecular variation of field intensities and dipole moments" Earth Planet.Sci.Lett.139. 251-262 (1996)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1997 Final Research Report Summary
  • [Publications] Starchenko, S.and M.Kono: "Numerical verification of MEGA in axisymmetric alphaomega-dynamo" Geophys.Astrophys.Fluid Dynam.82. 93-123 (1996)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1997 Final Research Report Summary
  • [Publications] Uchimura, H., M.Kono, H.Tsunakawa, G.Kimura, Q.Wei, T.Hao, and H.Liu: "Paleomagnetism of Late Mesozoic rocks from Northeastern China : the role of the Tan-Lu fault in the North China Block" Tectonophysics. 262. 301-319 (1996)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1997 Final Research Report Summary
  • [Publications] Kono, M.: "Paleosecular variation in field directions due to randomly varying Gauss coefficients" J.Geomag.Geoelectr.49. 615-631 (1997)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1997 Final Research Report Summary
  • [Publications] Kono, M.: "Distributions of paleomagnetic directions and poles" Phys.Earth Planet.Inter.103. 313-327 (1997)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1997 Final Research Report Summary
  • [Publications] Tanaka,H., … M.Kono, and M.O.McWilliams.: "Paleomagnetism and chronology of the central Taupo Volcanic Zone,New Zealand." Geophys.J.Int.124. 919-934 (1996)

    • Related Report
      1997 Annual Research Report
  • [Publications] Kono,M. and O.Hiroi.: "Paleosecular variation of field intensities and dipole moments" Earth Planet. Sci.Lett.139. 251-262 (1996)

    • Related Report
      1997 Annual Research Report
  • [Publications] Starchenko,S. and M.Kono: "Numerical verification of MEGA in axisymmetric αω-dynamo" Geophys. Astrophys. Fluid Dynam.82. 93-123 (1996)

    • Related Report
      1997 Annual Research Report
  • [Publications] Uchimura,H., M.Kono, …: "Paleomagnetism of Late Mesozoic rocks from Northeastern China : the role of the Tan-Lu fault in the North China Block," Tectonophysics. 262. 301-319 (1996)

    • Related Report
      1997 Annual Research Report
  • [Publications] Kono,M.: "Paleosecular variation in field directions due to randomly varying Gauss coefficients" J.Geomag.Geoelectr.49. 615-631 (1997)

    • Related Report
      1997 Annual Research Report
  • [Publications] Kono,M.: "Distributions of paleomagnetic directions and poles" Phys.Earth Planet. Inter.103. 313-327 (1997)

    • Related Report
      1997 Annual Research Report
  • [Publications] Kono,M.and O.Hiroi: "Paleosecular variation of field intensities and dipole moments" Earth Planet.Sci.Lett.139. 251-262 (1996)

    • Related Report
      1996 Annual Research Report
  • [Publications] Starchenko,S.and M.Kono: "Numerical verification of MEGA in axisymmetric αω-dynamo" Geophys.Astrophys.Fluid Dynam.82. 93-123 (1996)

    • Related Report
      1996 Annual Research Report
  • [Publications] Uchimura,H.,M.Kono,H.Tsunakawa,G.Kimura: "Paleomagnetism of Late Mesozoic rocks from Northeastern China:the role of the Tan-Lu fault in the North China Block" Tectonophysics. 262. 301-319 (1996)

    • Related Report
      1996 Annual Research Report
  • [Publications] Kono,M.: "Paleosecular variation in field directions due to randomly varying Gauss coefficients" J.Geomag.Geoelectr.(in press). (1997)

    • Related Report
      1996 Annual Research Report
  • [Publications] 河野 長: "地磁気と生命" 健康管理. 508. 5-20 (1996)

    • Related Report
      1996 Annual Research Report
  • [Publications] 河野 長: "フルモデル時代にはいった地球ダイナモ" 科学. 66. 817-825 (1996)

    • Related Report
      1996 Annual Research Report

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Published: 1996-04-01   Modified: 2016-04-21  

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