geomagnetic

Geomagnetic refers to the Earth's magnetic field and to the study of its properties, variations, and origin. It is a field within geophysics that investigates how the planet generates and maintains its magnetic field and how that field interacts with the space environment around Earth.

The Earth's magnetic field is mainly produced by dynamo action in the liquid iron of the outer core. The current field resembles a dipole tilted relative to the rotation axis, but it undergoes slow, continuous changes known as secular variation. Surface measurements show variability in field strength, direction, and inclination, with local values ranging over tens of thousands of nanoteslas and the field direction changing over time.

Measurement and modeling rely on a global network of magnetometers and satellites. The International Geomagnetic Reference Field (IGRF) and the World Magnetic Model (WMM) provide standardized representations of the field at any location and time. These models are continually updated as new data are collected from observatories and space missions.

Geomagnetic disturbances are driven by solar activity and are studied as space weather. Geomagnetic storms arise when solar wind and coronal mass ejections interact with the magnetosphere, increasing currents, compressing the magnetosphere, and producing auroras. Severe storms can impact power grids, satellites, aviation, and communications, and are tracked using indices such as Dst and Kp.

Applications of geomagnetic knowledge include navigation using compasses and corrections for modern inertial systems, paleomagnetism to reconstruct past plate movements and continental configurations, and geophysical exploration for mineral and hydrocarbon resources.