Fluid motion in the outer core maintains much of Earth's magnetic field.
Key knowledge
Geodynamo models describe generation and maintenance of Earth's intrinsic magnetic field by motion of electrically conducting fluid in the outer core. Numerical models and surface or satellite observations constrain the evolving field and core dynamics.
Conditions and scope
The main internal field is distinct from crustal and externally generated magnetic contributions.
Core-flow and field reconstructions remain model-dependent; a simulated field is not a direct observation of every core motion.
Sources · 1
References
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Geodynamo models describe generation and maintenance of Earth's intrinsic magnetic field by motion of electrically conducting fluid in the outer core. Numerical models and surface or satellite observations constrain the evolving field and core dynamics.
The dynamo model concerns the fluid outer core; field and seismic constraints are distinct observations.
The solar wind carries charged particles, including protons and electrons, and solar magnetic field into interplanetary space. Its flow can compress a planetary magnetosphere. Magnetic reconnection changes field connectivity and permits energy transfer into the magnetosphere; particle energization and atmospheric interactions can produce auroral emission.
An internal magnetic source and external wind interaction are distinct mechanisms.
A weak-field linear isotropic rock model separates magnetizationM=M_r+χH into retained remanence and an induced response to localH. A scalar survey's anomaly relative to vector backgroundB₀ isΔF=|B₀+b|−|B₀|, approximatelyB̂₀·b when|b|≪|B₀|. The localized geological fieldb depends on magnetization, geometry and observation position; scalar anomalies alone do not uniquely recover those properties.
Core-field generation is distinct from crustal anomaly sources.