Earth's magnetic field

About: Earth's magnetic field is a research topic. Over the lifetime, 20360 publications have been published within this topic receiving 446747 citations. The topic is also known as: magnetic field of Earth & geomagnetic field.

Analyses on the geometrical structure of magnetic field in the current sheet based on cluster measurements

Abstract: The geometrical structure of the magnetic field is a critical character in the magnetospheric dynamics. Using the magnetic field data measured by the Cluster constellation satellites, the geometrical structure including the curvature radius, directions of curvature, and normal of the osculating planes of the magnetic field lines within the current sheet/neutral sheet have been investigated. The results are ( 1) Inside of the tail neutral sheet (NS), the curvature of magnetic field lines points towards Earth, the normal of the osculating plane points duskward, and the characteristic half width ( or the minimum curvature radius) of the neutral sheet is generally less than 2 R-E, for many cases less than 1600 km. (2) Outside of the neutral sheet, the curvature of magnetic field lines pointed northward ( southward) at the north ( south) side of NS, the normal of the osculating plane points dawnward, and the curvature radius is about 5 R-E similar to 10 R-E. (3) Thin NS, where the magnetic field lines have the minimum of the curvature radius less than 0.25 R-E, may appear at all the local time between LT 20 hours and 4 hours, but thin NS occurs more frequently near to midnight than that at the dawnside and duskside. (4) The size of the NS is dependent on substorm phases. Generally, the NS is thin during the growth and expansion phases and grows thick during the recovery phase. (5) For the one-dimensional NS, the half thickness and flapping velocity of the NS could be quantitatively determined. Therefore the differential geometry analyses based on Cluster 4-point magnetic measurements open a window for visioning the three-dimensional static and dynamic magnetic field structure of geomagnetosphere.

Fifth-generation lithospheric magnetic field model from CHAMP satellite measurements

Abstract: [1] Six years of low-orbit CHAMP satellite magnetic measurements have provided an exceptionally high-quality data resource for lithospheric magnetic field modeling and interpretation. Here we describe the fifth-generation satellite-only magnetic field model MF5. The model extends to spherical harmonic degree 100. As a result of careful data selection, extensive corrections, filtering, and line leveling, the model has low noise levels, even if evaluated at the Earth's surface. The model is particularly suited for inferring large-scale structure and composition of the lithosphere. It is also meant to serve as the long-wavelength part of continental- and global-scale marine and aeromagnetic anomaly maps.

Chaotic particle dynamics near a two-dimensional magnetic neutral point with application to the geomagnetic tail

Abstract: The dynamical system composed of a charged particle moving in a two-dimensional magnetic field containing a neutral point, with and without a perpendicular electric field, is studied. The system is found to be nonintegrable and chaotic. Lyapunov characteristic exponents are calculated for the various types of chaotic orbits. When parameters relevant to the magnetotail are used it is found that the stochastic nature of the motion is more important for a thick current sheet (20,000 km) than for a thin sheet (1000 km). Some consequences of this stochasticity are discussed, including the suggestion of a collisionless, “chaotic conductivity”; this represents the collisionlike randomizing effect of the chaotic dynamics.