Heterogeneity at the bottom of the mantle and geomagnetic non-dipole field

• Project/Area Number: 23540491
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Solid earth and planetary physics
• Research Institution: The University of Tokyo
• Principal Investigator: SHIMIZU Hisayoshi 東京大学, 地震研究所, 准教授 (70302619)
• Project Period (FY): 2011-04-28 – 2015-03-31
• Project Status: Completed (Fiscal Year 2014)
• Budget Amount: ¥2,210,000 (Direct Cost: ¥1,700,000、Indirect Cost: ¥510,000); Fiscal Year 2013: ¥910,000 (Direct Cost: ¥700,000、Indirect Cost: ¥210,000); Fiscal Year 2012: ¥910,000 (Direct Cost: ¥700,000、Indirect Cost: ¥210,000); Fiscal Year 2011: ¥390,000 (Direct Cost: ¥300,000、Indirect Cost: ¥90,000)
• Keywords: 地磁気 / 核ーマントル境界 / 電気伝導度 / 地球中心核 / マントル電気伝導度 / 地磁気変動 / ダイナモ理論

Outline of Final Research Achievements

In case that the heterogeneous mantle electrical conductivity and simple magnetic field at the core-mantle boundary are the cause of the vertical magnetic field component at the equatorial region, it is essential for the simple magnetic field to contain the toroidal magnetic field component. The heterogeneous mantle converts the toroidal magnetic field at the core-mantle boundary to an observable magnetic field at the Earth’s surface. Detection of the magnetic field and accompanying electric field variation enables us to constrain the electrical conductivity of the heterogeneous block at the bottom of the mantle.

Research Products

• [Journal Article] Motional magnetotellurics by long oceanic waves (2015)
  • Author(s): Shimizu, H. and Utada, H.
  • Journal Title: Geophysical Journal International Volume: 201 Issue: 1 Pages: 390-405
  • DOI: 10.1093/gji/ggv030
  • Peer Reviewed
• [Journal Article] Waves and linear stability of magnetoconvection in a rotating cylindrical annulus (2014)
  • Author(s): Hori, K., Takehiro, S., and Shimizu, H.
  • Journal Title: Physics of the Earth and Planetary Interiors Volume: 236 Pages: 16-35
  • DOI: 10.1016/j.pepi.2014.07.010
  • Peer Reviewed
• [Presentation] Further examination of the geoelectromagnetic jerk hypothesis (2015)
  • Author(s): Shimizu, H. and Utada H.
  • Organizer: 日本地球惑星科学連合大会
  • Place of Presentation: 幕張メッセ（千葉県千葉市）
  • Year and Date: 2015-05-26
• [Presentation] Influence of the electrical conductivity heterogeneity in the D” layer on the flow and magnetic field at the surface of the core (2014)
  • Author(s): Shimizu, H. and Utada H.
  • Organizer: American Geophysical Union Fall Meeting
  • Place of Presentation: サンフランシスコ（米国）
  • Year and Date: 2014-12-15
• [Presentation] Influence of the electrical conductivity heterogeneity in the D” layer on the flow and magnetic field at the surface of the core (2014)
  • Author(s): Shimizu, H. and Utada H.
  • Organizer: SEDI International Symposium 2014
  • Place of Presentation: 湘南国際村センター（神奈川県三浦郡）
  • Year and Date: 2014-08-03
• [Presentation] Influence of the electrical conductivity heterogeneity at the CMB on the flow and magnetic field in the core (2014)
  • Author(s): Shimizu, H.
  • Organizer: 日本地球惑星科学連合大会
  • Place of Presentation: パシフィコ横浜（神奈川県横浜市）
  • Year and Date: 2014-04-29
• [Presentation] Influence of the electrical conductivity heterogeneity at the CMB on the flow and magnetic field in the core (2014)
  • Author(s): Hisayoshi Shimizu
  • Organizer: 日本地球惑星科学連合大会
  • Place of Presentation: 神奈川県横浜市
• [Presentation] Influence of the electrical conductivity heterogeneity at the bottom of the mantle on the flow and magnetic field beneath the CMB (2013)
  • Author(s): Hisayoshi Shimizu
  • Organizer: SEDI (Study of Earth's Deep Interior) プレシンポジウム
  • Place of Presentation: 神奈川県三浦郡葉山町
• [Presentation] Influence of electrical conductivity heterogeneity in the D'' layer on geomagnetic jerks (2012)
  • Author(s): Hisayoshi Shimizu and Hisashi Utada
  • Organizer: Study of the Earth's Interior 2012 Symposium
  • Place of Presentation: Leeds, UK
• [Presentation] Influence of electrical conductivity heterogeneity in the D'' layer on geomagnetic jerks (2012)
  • Author(s): Hisayoshi Shimizu and Hisashi Utada
  • Organizer: American Geophysical Union Fall Meeting
  • Place of Presentation: San Francisco, USA