Understanding of a Mechanism of Geomagnetic Field Reversals by Highly Precise Numerical Simulations of the Geodynamo

• Project/Area Number: 18340131
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Solid earth and planetary physics
• Research Institution: Tokyo Institute of Technology
• Principal Investigator: HONKURA Yoshimori Tokyo Institute of Technology, 大学院・理工学研究科, 教授 (00114637)
• Co-Investigator(Kenkyū-buntansha): MATSUSHIMA Masaki 東京工業大学, 大学院・理工学研究科, 助教 (20242266)
• Project Period (FY): 2006 – 2008
• Project Status: Completed (Fiscal Year 2008)
• Budget Amount: ¥15,100,000 (Direct Cost: ¥13,000,000、Indirect Cost: ¥2,100,000); Fiscal Year 2008: ¥4,420,000 (Direct Cost: ¥3,400,000、Indirect Cost: ¥1,020,000); Fiscal Year 2007: ¥4,680,000 (Direct Cost: ¥3,600,000、Indirect Cost: ¥1,080,000); Fiscal Year 2006: ¥6,000,000 (Direct Cost: ¥6,000,000)
• Keywords: 地球ダイナモ / 地磁気逆転 / 数値シミュレーション / MHDダイナモ / コア・ダイナミクス / 地磁気逆転メカニズム / グリッドコンピューティング

Research Abstract

地磁気逆転メカニズムの解明に向けて, 地球ダイナモの高精度数値シミュレーションを実施した. 速度場と磁場の特徴的長さスケールに着目して, 地球コア内における粘性散逸とオーム散逸を見積もった. 磁場の極性が逆転するときと, 逆転に至らずに元に戻るエクスカーションのときには, 磁場生成過程に明らかな違いがあることを示した. また, コア-マントル境界における熱流束分布及びその大きさがコアのダイナミクス及び磁場強度に対していかに影響するかを示した.

Research Products

• [Journal Article] Effects of thermally heterogeneous structure in the lowermost mantle on the geomagnetic field strength (2008)
  • Author(s): Takahashi, F., H. Tsunakawa, M. Matsushima, N. Mochizuki, and Y. Honkura
  • Journal Title: Earth Planet. Sci. Lett. 272 Pages: 738-746
  • Peer Reviewed
• [Journal Article] Scale variability in convectiondriven MHD dynamos at low Ekman number (2008)
  • Author(s): Takahashi, F., M. Matsushima, and Y. Honkura
  • Journal Title: Phys. Earth Planet. Inter. 167 Pages: 168-178
  • Peer Reviewed
• [Journal Article] Scale variability in convection-driven MHD dynamos at low Ekman number (2008)
  • Author(s): Takahashi, F., Matsushima, M., Honkura, Y.
  • Journal Title: Physics of the Earth and Planetary Interiors 167 Pages: 168-178
  • Peer Reviewed
• [Journal Article] Effects of thermally heterogeneous structures in the lowermost mantle on the geomagnetic field strength (2008)
  • Author(s): Takahashi, F., Tsunakawa, H., Matsushima, M., et al.
  • Journal Title: Earth and Planetary Science Letters 272 Pages: 738-746
  • Peer Reviewed
• [Journal Article] Scale variability in convection-driven MHD dynamos at low Ekman number (2008)
  • Author(s): Takahashi, F., Matsushima, M., and Honkura, Y.
  • Journal Title: Physics of the Earth and Planetary Interiors (In press)
  • Peer Reviewed
• [Journal Article] A numerical study on magnetic polarity transition in an MHD dynamo model (2007)
  • Author(s): Takahashi, F., M. Matsushima, and Y. Honkura
  • Journal Title: Earth Planets Space 59 Pages: 665-673
  • NAID: 10024498402
  • Peer Reviewed
• [Journal Article] Distinctive difference between the polarity reversal and excursion in an MHD dynamo model, in 2007 Annual Report, Research Center for the Evolving Earth and Planets (2007)
  • Author(s): Takahashi, F., M. Matsushima, and Y. Honkura
  • Journal Title: COE21 Program, Tokyo Institute of Technology
• [Journal Article] A numerical study on magnetic polarity transition in an MHD dynamo (2007)
  • Author(s): Takahashi, F., Matsushima, M., and Honkura, Y.
  • Journal Title: Earth, Planets and Space 59 Pages: 665-673
  • Peer Reviewed
• [Journal Article] Dipolar and non dipolar dynamos in a thin spherical shell geometry, in 2006 Annual Report, Research Center for the Evolving Earth and Planets (2006)
  • Author(s): Takahashi, F., M. Matsushima, and Y. Honkura
  • Journal Title: COE21 Program, Tokyo Institute of Technology
• [Journal Article] Reexamination of a scalesimilarity model for the subgrid scale flux in the Earth's core (2006)
  • Author(s): Matsushima, M
  • Journal Title: Geophys. Astrophys. Fluid Dynam 100 Pages: 363-377
  • Peer Reviewed
• [Journal Article] Scale variability in convective-driven MHD dynamos at low Ekman number (2006)
  • Author(s): Takahashi, F., Matsushima, M., Honkura, Y.
  • Journal Title: AGU 2006 Faull Meeting Abstract(CD version)
• [Journal Article] Fluid flow near the Earth's core surface derived from geomagnetic field models (2006)
  • Author(s): Matsushima, M., Takahashi, F., Honkura, Y.
  • Journal Title: AGU 2006 Fall Meeting Abstract(CD version)
• [Journal Article] Reexamination of a scale-similarity model for the subgrid-scale flux in the Earth's core (2006)
  • Author(s): Matsushima, M.
  • Journal Title: Geophysical Astrophysical Fluid Dynamics 100 Pages: 363-377
• [Presentation] Effects of thermally heterogeneous structure in the lowermost mantle on the geomagnetic field strength (2008)
  • Author(s): Takahashi, F., H. Tsunakawa, M. Matsushima, N. Mochizuki, and Y. Honkura
  • Organizer: The 11^<th> Symposium of Study of the Earth' s Deep Interior
  • Place of Presentation: Kunming, China
  • Year and Date: 2008-07-28
• [Presentation] Fluid flow near the Earth' s core surface derived from geomagnetic field models (2) (2008)
  • Author(s): Matsushima, M., F. Takahashi, and Y.Honkura
  • Organizer: 日本地球惑星科学連合2008年大会
  • Place of Presentation: 千葉
  • Year and Date: 2008-05-28
• [Presentation] Fluid flow near the Earth's core surface derived from geomagnetic field models (2) (2008)
  • Author(s): Matsushima, M., Takahashi, F., Honkura, Y.
  • Organizer: 日本地球惑星科学連合2008年大会
  • Place of Presentation: 千葉, 日本
  • Year and Date: 2008-05-28
• [Presentation] Effects of thermally heterogeneous structure in the lowermost mantle on the geomagnetic field strength (2007)
  • Author(s): Takahashi, F., H. Tsunakawa, M. Matsushima, N. Mochizuki, and Y. Honkura
  • Organizer: American Geophysical Union 2007 Fall Meeting
  • Place of Presentation: San Francisco, U.S.A
  • Year and Date: 2007-12-12
• [Presentation] Fluid flow near the Earth' s core surface derived from geomagnetic field models with constraint of radial dependence (2007)
  • Author(s): Matsushima, M., F. Takahashi, and Y. Honkura
  • Organizer: American Geophysical Union 2007 Fall Meeting
  • Place of Presentation: San Francisco, U.S.A
  • Year and Date: 2007-12-12
• [Presentation] Fluid flow near the Earth's core surface derived from geomagnetic field models with constraint of radial dependence (2007)
  • Author(s): Matsushima, M., Takahashi, F., and Honkura, Y.
  • Organizer: American Geophysical Union 2007 Fall Meeting
  • Place of Presentation: San Francisco, U.S.A.
  • Year and Date: 2007-12-12
• [Presentation] Effects of thermally heterogeneous structure in the lowermost mantle on the geomagnetic field strength (2007)
  • Author(s): Takahashi, F., Tsunakawa, H., Matsushima, M., Mochizuki, N., and Honkura, Y.
  • Organizer: American Geophysical Union 2007 Fall Meeting
  • Place of Presentation: San Francisco, U.S.A.
  • Year and Date: 2007-12-12
• [Presentation] Effects of thermally heterogeneous structure in the lowermost mantle on the geomagnetic field strength (2007)
  • Author(s): Takahashi, F., H. Tsunakawa, M. Matsushima, N. Mochizuki, and Y. Honkura
  • Organizer: 第122回地球電磁気・地球惑星圏学会
  • Place of Presentation: 名古屋
  • Year and Date: 2007-10-01
• [Presentation] Effects of thermally heterogeneous structure in the lowermost mantle on the geomagnetic field strength (2007)
  • Author(s): 高橋 太, 綱川秀夫, 松島政貴, 望月伸竜, 本蔵義守
  • Organizer: 第122回地球電磁気・地球惑星圏学会
  • Place of Presentation: 名古屋,日本
  • Year and Date: 2007-10-01
• [Presentation] Fluid flow near the Earth' s core surface derived from geomagnetic field models with constraint of radial dependence (2007)
  • Author(s): Matsushima, M., F. Takahashi, and Y. Honkura
  • Organizer: 第122回地球電磁気・地球惑星圏学会
  • Place of Presentation: 名古屋
  • Year and Date: 2007-09-30
• [Presentation] Fluid flow near the Earth's core surface derived from geomagnetic field models with constraint of radial dependence (2007)
  • Author(s): 松島政貴, 高橋 太, 本蔵義守
  • Organizer: 第122回地球電磁気・地球惑星圏学会
  • Place of Presentation: 名古屋,日本
  • Year and Date: 2007-09-30
• [Presentation] Magnetic field intensification by lateral variation of the core mantle boundary heat flow in numerical dynamos (2007)
  • Author(s): Takahashi, F., M. Matsushima, and Y. Honkura
  • Organizer: 日本地球惑星科学連合2007年大会
  • Place of Presentation: 千葉
  • Year and Date: 2007-05-21
• [Presentation] Fluid flow near the Earth' s core surface derived from geomagnetic field models (2007)
  • Author(s): Matsushima, M., F. Takahashi, and Y. Honkura
  • Organizer: 日本地球惑星科学連合2007年大会
  • Place of Presentation: 千葉
  • Year and Date: 2007-05-21
• [Presentation] Fluid flow near the Earth's core surface derived from geomagnetic field models (2007)
  • Author(s): 松島政貴, 高橋 太, 本蔵義守
  • Organizer: 日本地球惑星科学連合2007年大会
  • Place of Presentation: 千葉,日本
  • Year and Date: 2007-05-21
• [Presentation] ダイナモモデルにおけるコアマントル境界での熱流束分布の変化に伴う磁場の強化 (2007)
  • Author(s): 高橋 太, 松島政貴, 本蔵義守
  • Organizer: 日本地球惑星科学連合2007年大会
  • Place of Presentation: 千葉,日本
  • Year and Date: 2007-05-21
• [Presentation] Scale variability in convectiondriven dynamos at low Ekman number (2006)
  • Author(s): Takahashi, F., M. Matsushima, and Y. Honkura
  • Organizer: American Geophysical Union 2006 Fall Meeting
  • Place of Presentation: San Francisco, U.S.A
  • Year and Date: 2006-12-14
• [Presentation] Scale variability in convectiondriven dynamos at low Ekman number (2006)
  • Author(s): Takahashi, F., M. Matsushima, and Y. Honkura
  • Organizer: 第120回地球電磁気・地球惑星圏学会
  • Place of Presentation: 相模原
  • Year and Date: 2006-11-05
• [Presentation] Fluid flow near the Earth's core surface derived from geomagnetic field models (2006)
  • Author(s): Matsushima, M., F. Takahashi, and Y. Honkura
  • Organizer: 第120回地球電磁気・地球惑星圏学会
  • Place of Presentation: 相模原
  • Year and Date: 2006-11-05
• [Presentation] Fluid flow near the Earth' s core surface derived from geomagnetic field models (2002)
  • Author(s): Matsushima, M., F. Takahashi, and Y. Honkura
  • Organizer: American Geophysical Union 2006 Fall Meeting
  • Place of Presentation: San Francisco, U.S.A
  • Year and Date: 2002-12-14