地磁気波動は,地球のコアの上部で安定した層化を明らかにしています
1Department of Earth and Planetary Science, University of California, Berkeley, California 94720, USA.
Nature
|March 28, 2014
まとめ
地磁気波動は,層分かれした地球の核層のMAC波によって説明されます. この発見は,潜在的に熱的または化学的な140km厚さの層が,コアダイナミクスと磁場に影響を及ぼすことを示唆しています.
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:
- 地球の地磁場は60年間の変動を示し,おそらくコアダイナミクスから発生しています.
- 扭転振動とMAC波はメカニズムとして提案されているが,現存するモデルは,観測された期間を説明する課題に直面している.
研究 の 目的:
- 地磁気世俗的変動と二極場の変動を説明するMAC波の役割を調査する.
- 核-マントル境界における潜在的分層層の物理的特性を決定する.
主な方法:
- 地磁気長期変動データを分析して,時間依存のゾーンフローを推論する.
- 安定した階層化されたコア条件下でのMAC波動のモデリング.
- モデルの予測を観測された地磁気変動と二極場変動と比較する.
主要な成果:
- 安定した層状のコアにあるMAC波は,観測されたゾーンフローと二極フィールドの変動を正確に記述します.
- 特定の浮力周波数を持つ140キロメートルの厚さの分層層層が必要である.
- この層は,熱分層化 (約13TWのコア熱流) または化学分層化から生じる可能性があります.
結論:
- MAC波は,60年間の地磁気変動の実行可能な説明を提供します.
- 核の上部に層状の層が存在することは,観測可能な磁場変動に影響します.
- この分層は,磁場を再生するプロセスの直接的な観察を遮断します.
関連する概念動画
01:27Magnetic Fields
6.0K
A moving charge or a current creates a magnetic field in the surrounding space, in addition to its electric field. The magnetic field exerts a force on any other moving charge or current that is present in the field. Like an electric field, the magnetic field is also a vector field. At any position, the direction of the magnetic field is defined as the direction in which the north pole of a compass needle points.
A magnetic field is defined by the force that a charged particle experiences...
A magnetic field is defined by the force that a charged particle experiences...
6.0K
01:31Magnetic Susceptibility and Permeability
2.9K
In linear magnetic materials, like paramagnets and diamagnets, magnetization is proportional to the magnetic field intensity. The constant of proportionality, a dimensionless number, is called magnetic susceptibility. The value of the susceptibility depends on the type of material.
When diamagnetic materials are placed under an external magnetic field, the moments opposite to the field are induced. Hence, the susceptibility for diamagnets has a minimal negative value of 10-5–10-6. Since...
When diamagnetic materials are placed under an external magnetic field, the moments opposite to the field are induced. Hence, the susceptibility for diamagnets has a minimal negative value of 10-5–10-6. Since...
2.9K
01:28Magnetostatic Boundary Conditions
1.9K
An electric field suffers a discontinuity at a surface charge. Similarly, a magnetic field is discontinuous at a surface current. The perpendicular component of a magnetic field is continuous across the interface of two magnetic mediums. In contrast, its parallel component, perpendicular to the current, is discontinuous by the amount equal to the product of the vacuum permeability and the surface current. Like the scalar potential in electrostatics, the vector potential is also continuous...
1.9K
01:11Atomic Nuclei: Larmor Precession Frequency
3.5K
The earth's gravitational field produces a 'twisting force' perpendicular to the angular momentum of a spinning mass (such as a spinning top) that causes the mass to 'wobble' around the gravitational field axis in a phenomenon called precession. Similarly, the magnetic moment (μ) of a spinning nucleus precesses due to an external magnetic field directed along the z-axis. The precession of the magnetic moment vector about the magnetic field is called Larmor precession,...
3.5K
01:19Magnetic Field Lines
5.4K
The representation of magnetic fields by magnetic field lines is very useful in visualizing the strength and direction of the magnetic field. Each of the magnetic field lines forms a closed loop. The field lines emerge from the north pole (N), loop around to the south pole (S), and continue through the bar magnet back to the north pole.
Magnetic field lines follow several hard-and-fast rules:
Magnetic field lines follow several hard-and-fast rules:
5.4K
01:23Atomic Nuclei: Nuclear Relaxation Processes
1.1K
In the absence of an external magnetic field, nuclear spin states are degenerate and randomly oriented. When a magnetic field is applied, the spins begin to precess and orient themselves along (lower energy) or against (higher energy) the direction of the field. At equilibrium, a slight excess population of spins exists in the lower energy state. Because the direction of the magnetic field is fixed as the z-axis, the precessing magnetic moments are randomly oriented around the z-axis.
1.1K