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- Peter E. Driscoll
- Department of Terrestrial Magnetism Carnegie Institution for Science Washington DC USA
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- Zhixue Du
- Geophysical Laboratory Carnegie Institution for Science Washington DC USA
書誌事項
- 公開日
- 2019-07-22
- 権利情報
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- http://onlinelibrary.wiley.com/termsAndConditions#vor
- DOI
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- 10.1029/2019gl082915
- 公開者
- American Geophysical Union (AGU)
この論文をさがす
説明
<jats:title>Abstract</jats:title><jats:p>In a metal, as in Earth's core, the thermal and electrical conductivities are assumed to be correlated. In a planetary dynamo this implies a contradiction: that both electrical conductivity, which makes it easier to induce current and magnetic field, and conductive heat transport, which hinders thermal convection, should increase simultaneously. Here we show that this contradiction implies that the magnetic induction rate peaks at a particular value of electrical and thermal conductivity and derive the low‐ and high‐conductivity limits for thermal dynamo action. A dynamo regime diagram is derived as a function of electrical conductivity and temperature for Earth's core that identifies four distinct dynamo regimes: no dynamo, thermal dynamo, compositional dynamo, and thermocompositional dynamo. Estimates for the temperature‐dependent electrical conductivity of the core imply that the geodynamo may have come close to its high‐conductivity “no dynamo” limit prior to inner core nucleation, consistent with recent paleomagnetic observations.</jats:p>
収録刊行物
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- Geophysical Research Letters
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Geophysical Research Letters 46 (14), 7982-7989, 2019-07-22
American Geophysical Union (AGU)
