Effects of double diffusive convection and stable stratification on the geodynamo
| Project/Area Number |
24740303
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| Research Category |
Grant-in-Aid for Young Scientists (B)
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| Allocation Type | Multi-year Fund |
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| Research Field |
Solid earth and planetary physics
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| Research Institution | Kyushu University (2013-2014)
Tokyo Institute of Technology (2012) |
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Principal Investigator |
TAKAHASHI Futoshi 九州大学, 理学(系)研究科(研究院), 准教授 (20467012)
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| Project Period (FY) |
2012-04-01 – 2015-03-31
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| Project Status |
Completed (Fiscal Year 2014)
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| Budget Amount *help |
¥4,030,000 (Direct Cost: ¥3,100,000、Indirect Cost: ¥930,000)
Fiscal Year 2014: ¥1,040,000 (Direct Cost: ¥800,000、Indirect Cost: ¥240,000)
Fiscal Year 2013: ¥1,040,000 (Direct Cost: ¥800,000、Indirect Cost: ¥240,000)
Fiscal Year 2012: ¥1,950,000 (Direct Cost: ¥1,500,000、Indirect Cost: ¥450,000)
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| Keywords | 地球ダイナモ / コア / 二重拡散対流 / 安定成層 |
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| Outline of Final Research Achievements |
To understand effects of a stably stratified layer beneath the core-mantle boundary on the geodynamo and its origin, we performed dynamo simulations in a rotating spherical shell. We have developed a dynamo code to simulate thermal and compositional convection. Two driving agents have different diffusivities and thus, convection is treated as double diffusive convection. When energy injection from compositional buoyancy occupies at least 40 % of the total injection, an Earth-like dipolar magnetic field is maintained. Then, a stably stratified layer due to thermal or compositional effects is imposed in dynamo simulations, which should yield dipolar magnetic fields in case of no stably stratified layer. Consequently, it is implied that the origin of the stable layer might be thermal. Furthermore, we have carried out stability analysis of an extended disk dynamo model and find a relation between subcritical behavior of the dynamo and efficiency of the magnetic field generation process.
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Report
(4 results)
Research Products
(16 results)
