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Magnetic Tweezers for the Measurement of Twist and Torque
Published on: May 19, 2014
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地球の核内部の高速なトルション波と強い磁場
Nicolas Gillet1, Dominique Jault, Elisabeth Canet
1Laboratoire de Géophysique Interne et Tectonophysique, CNRS, Université Joseph Fourier, BP 53, 38041 Grenoble cedex 9, France. nicolas.gillet@obs.ujf-grenoble.fr
Nature
|May 7, 2010
まとめ
科学者は,ジオダイナモモデルとコアフロー分析を使用して,地球のコア磁場強さを推定しています. この研究は,数値シミュレーションと地磁気データを調和させ,これまで考えられていたよりも強い内部フィールドを明らかにしました.
科学分野:
- 地質物理学 地質物理学とは地質物理学です.
- 地球科学 地球科学 地球科学
- マグネトヒドロダイナミクス
背景:
- 地球のコア磁場は,直接測定できません.
- 内部フィールド強度の推定は大きく異なるが,一部のモデルは数ミリセラを示唆し,他のモデルははるかに弱いフィールド (0.2mT) を示している.
- 地球の回転の60年間の信号は,核内の磁気水力ダイナミックなトルション波と関連しています.
研究 の 目的:
- 数値的なジオダイナモモデルと地磁気データの不一致を調整する.
- 地球の外核内の磁場の強さを決定するために.
- マグネトヒドロダイナミックなトルション波の性質と,観測された地球回転信号との関連を調査する.
主な方法:
- 地磁気データを用いてコアフローモデルのアンサンブル逆転.
- マグネトヒドロダイナミックトルション波とその伝播時間の分析.
- 観測データと数値ジオダイナモシミュレーションの調和.
主要な成果:
- 地球の昼間の長さの観測された変化と一致する,6年間の再発期を持つトルション波が特定されました.
- 外核を通るこの波の伝播時間は,約2mTの放射性磁場強度に対応するアルフヴェン波の遅さを示唆しています.
- これは推定の平方根平均 (r.m.s.) を意味する. 磁場強度4mTの磁場は,地球の中核内にある.
結論:
- この研究は,地球の内部磁場強さの調整された見積もりを提供します.
- マグネトヒドロダイナミックなトルション波は,地球の自転を調節する上で重要な役割を果たします.
- この発見は,地質学運動と地磁気データの以前の解釈よりも強い内部磁場を裏付けている.
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