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Changes in surface environments and Earth's interior and Earth's rotational variations

Research Project

Project/Area Number 22540440
Research Category

Grant-in-Aid for Scientific Research (C)

Allocation TypeSingle-year Grants
Section一般
Research Field Solid earth and planetary physics
Research InstitutionKyushu University

Principal Investigator

NAKADA Masao  九州大学, 大学院・理学研究院, 教授 (50207817)

Project Period (FY) 2010 – 2012
Project Status Completed (Fiscal Year 2012)
Budget Amount *help
¥2,860,000 (Direct Cost: ¥2,200,000、Indirect Cost: ¥660,000)
Fiscal Year 2012: ¥520,000 (Direct Cost: ¥400,000、Indirect Cost: ¥120,000)
Fiscal Year 2011: ¥910,000 (Direct Cost: ¥700,000、Indirect Cost: ¥210,000)
Fiscal Year 2010: ¥1,430,000 (Direct Cost: ¥1,100,000、Indirect Cost: ¥330,000)
Keywords地球回転変動 / マントル対流 / コア対流 / マントルレオロジー / 氷床変動 / チャンドラー章動 / D"層 / 磁場変動 / コア・マントル結合 / チャンドラー極運動 / コアダイナミクス / マントル深部レオロジー
Research Abstract

Rapid geomagnetic fluctuations with periods less than a few years, so called geomagnetic jerks, seem to be coincident with changes in Earth’s length of day (LOD) and phase of the Chandler wobble. We indicated that rapid accelerations in the CMB flow can produce torques at the CMB generating observed LOD derivative with ~0.1 ms yr-1, but do not produce much for the polar motion. On the other hand, viscosity of the D” layer of the Earth’s mantle, the lowermost layer in the Earth’s mantle, controls a number of geodynamic processes such as the Earth’s rotational variations due to mantle convection and glacial isostatic adjustment. We showed that the decay of Chandler wobble and semi-diurnal to 18.6 years tidal deformation combined with the constraints from the postglacial isostatic adjustment observations suggest that the effective viscosity in the bottom ~300 km layer is 1019-1020Pa s, and also the effective viscosity of the bottom part of the D” layer (~100 km thickness) is less than 1018Pa s. By considering these results and recent melting events of mountain glaciers and polar ice sheets, we are now studying the Earth’s rotational variations caused by the temporal changes in mantle convection.

Report

(4 results)
  • 2012 Annual Research Report   Final Research Report ( PDF )
  • 2011 Annual Research Report
  • 2010 Annual Research Report
  • Research Products

    (11 results)

All 2012 2011 Other

All Journal Article (5 results) (of which Peer Reviewed: 5 results) Presentation (6 results) (of which Invited: 1 results)

  • [Journal Article] The viscosity structure of the D" layer of the Earth's mantle inferred from the analysis of Chandler wobble and tidal deformation2012

    • Author(s)
      Nakada, M., Chihiro, I., Karato, S.
    • Journal Title

      Physics of the Earth and Planetary Interiors

      Volume: 2008-2009 Pages: 11-24

    • Related Report
      2012 Final Research Report
    • Peer Reviewed
  • [Journal Article] Low viscosity structure of the D" layer of the bottom of the Earth's mantle inferred from the analysis of Chandler wobble and tidal deformation2012

    • Author(s)
      Nakada, M., Karato, S
    • Journal Title

      Physics of the Earth and Planetary Interiors

      Volume: 192-193 Pages: 68-80

    • Related Report
      2012 Final Research Report
    • Peer Reviewed
  • [Journal Article] The viscosity structure of the D” layer of the Earth’s mantle inferred from the analysis of Chandler wobble and tidal deformation2012

    • Author(s)
      Masao Nakada, Chihiro Iriguchi, Shun-ichiro Karato (Masao Nakada)
    • Journal Title

      Physics of the Earth and Planetary Interiors

      Volume: 208-209 Pages: 11-24

    • Related Report
      2012 Annual Research Report
    • Peer Reviewed
  • [Journal Article] Low viscosity of the bottom of the Earth's mantle inferred from the analysis of Chandler wobble and tidal deformation2012

    • Author(s)
      Masao Nakada, Shun-ichiro Karato
    • Journal Title

      Physics of the Earth and Planetary Interiors

      Volume: 192-193 Pages: 68-80

    • Related Report
      2011 Annual Research Report
    • Peer Reviewed
  • [Journal Article] Earth's rotational variations due to rapid surface flows at both boundaries of the outer core2011

    • Author(s)
      Nakada, M.
    • Journal Title

      Geophysical Journal International

      Volume: 184 Pages: 235-246

    • Related Report
      2012 Final Research Report 2010 Annual Research Report
    • Peer Reviewed
  • [Presentation] Viscosity structure of the D" layer inferred from the decay time of the Chandler wobble and tidal deformation2012

    • Author(s)
      Nakada, M., Karato, S.
    • Organizer
      The International Workshop on Core Dynamics 2012: East-west Asymmetry of Inner Core and Rotational Dynamics (invited)
    • Place of Presentation
      中国(武漢
    • Year and Date
      2012-05-22
    • Related Report
      2012 Final Research Report
  • [Presentation] Low viscosity of the bottom of the Earth's mantle inferred from the decay time of Chandler wobble and tidal deformation2011

    • Author(s)
      Nakada, M., Karato, S
    • Organizer
      American Geophysical Union (AGU) Fall Meeting 2011
    • Place of Presentation
      USA(サンフランシスコ)
    • Year and Date
      2011-12-05
    • Related Report
      2012 Final Research Report
  • [Presentation] Low viscosity of the bottom of the Earth's mantle inferred from the decay time of Chandler wobble and tidal deformation2011

    • Author(s)
      Masao Nakada, Shun-ichiro Karato
    • Organizer
      American Geophysical Union (AGU) Fall Meeting 2011
    • Place of Presentation
      サンフランシスコ
    • Year and Date
      2011-12-05
    • Related Report
      2011 Annual Research Report
  • [Presentation] チャンドラー運動の減衰時間と潮汐変形から推定されるD"層の粘性率2011

    • Author(s)
      中田正夫、 唐戸俊一郎
    • Organizer
      地球惑星科学連合学会
    • Place of Presentation
      千葉(幕張メッセ)
    • Year and Date
      2011-05-23
    • Related Report
      2012 Final Research Report
  • [Presentation] チャンドラー運動の減衰時間と潮汐変形から推定されるD"層の粘性率2011

    • Author(s)
      中田正夫, 唐戸俊一郎
    • Organizer
      日本地球惑星科学連合2011年度連合大会
    • Place of Presentation
      千葉(幕張メッセ)
    • Year and Date
      2011-05-23
    • Related Report
      2011 Annual Research Report
  • [Presentation] Viscosity structure of the D” layer of the decay time of the Chandler wobble and tidal deformation

    • Author(s)
      Masao Nakada, Shun-ichiro Karato (Masao Nakada)
    • Organizer
      The International Workshop on Core Dynamics 2012: East-west Asymmetry of Inner Core and Rotational Dynamics
    • Place of Presentation
      Wuhan (China)
    • Related Report
      2012 Annual Research Report
    • Invited

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Published: 2010-08-23   Modified: 2019-07-29  

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