| Project/Area Number |
18K03808
|
|---|
| Research Category |
Grant-in-Aid for Scientific Research (C)
|
| Allocation Type | Multi-year Fund |
|---|
| Section | 一般 |
|---|
| Review Section |
Basic Section 17040:Solid earth sciences-related
|
|---|
| Research Institution | Kyushu University |
|---|
Principal Investigator |
|
|---|
| Project Period (FY) |
2018-04-01 – 2021-03-31
|
| Project Status |
Completed (Fiscal Year 2020)
|
| Budget Amount *help |
¥4,420,000 (Direct Cost: ¥3,400,000、Indirect Cost: ¥1,020,000)
Fiscal Year 2020: ¥1,170,000 (Direct Cost: ¥900,000、Indirect Cost: ¥270,000)
Fiscal Year 2019: ¥1,300,000 (Direct Cost: ¥1,000,000、Indirect Cost: ¥300,000)
Fiscal Year 2018: ¥1,950,000 (Direct Cost: ¥1,500,000、Indirect Cost: ¥450,000)
|
|---|
| Keywords | 地球磁場 / ダイナモ / 地磁気永年変化 / 内核成長 / 10億年スケール / コア / 熱史 / 数値シミュレーション / 永年変化 |
|---|
| Outline of Final Research Achievements |
Dynamo action in the Earth's core is investigated based on numerical modeling of the geodynamo. In particular, we focus on spatial structure of the magnetic field and its secular variation in terms of three characteristic time scales, that is, annual, million-year, and billion-year scales. In annual scale, we have constructed a geomagnetic secular variation model using data assimilation approach. Then, in million-year scale, we have investigated correlation between frequency and duration of polarity reversals of the dipole field. Comparison with the latest paleomagnetic record was made, and then we have discussed the implications for the geomagnetic polarity reversals. Finally, in billion-year scale, we have studied core dynamics with various inner core size. It is suggested that dominant force balance in the past Earth's core is different from that in the present Earth's core.
|
| Academic Significance and Societal Importance of the Research Achievements |
本研究における成果を各時間スケールでまとめると次の3点になる。（１）内核の成長に伴う地球外核の特徴的な対流構造、ダイナミクスの変遷と、それらの変化に伴って実現される磁場構造とその永年変化から、地球の熱史と核のダイナミクスの関係を議論することができるようになった。（２）100万年スケールの古地磁気学的データに基づいて、過去の地磁気逆転と地球ダイナモの特徴を規定する際に重要な指標を提供することができた。（３）数年スケールで地球磁場の短期変動予測の実現可能性を示したことにより、より正確な地球磁場変動モデルの作成に寄与することができるようになった。
|
