Geometrical Structure Analysis of the Magnetic Field

Abstract

The geometrical configuration of the magnetic field underpins important research top- ics in magnetospheric physics. The magnetic field is the skeleton of the magnetosphere and plays a crucial role in determining the plasma distribution of particles, the occurrences of various macro and micro instabilities, the triggering and evolution of substorms and magnetic storms, etc. On the other hand, the magnetic reconnection process at the magnetopause and in the tail plasma sheet alters the topological structures of the magnetosphere, producing transient magnetic structures, such as rotational discontinuities, flux ropes, plasmoids, etc. The magnetometer investigation on the multiple spacecraft Cluster mission has made it possible to reveal the three-dimensional geometrical structure of the magnetic field in the magnetosphere, at least to local first order gradients. To achieve a full analysis of the local nature of the magnetic field geometry, several new gradient and curvature based methods have been proposed to describe the topological configurations of the key regions of magnetosphere. These methods are the curvature analysis method [Shen et al., 2003], magnetic field strength gradient method [Shen et al., 2003, 2007a], and the magnetic rotation analysis [MRA, see Shen et al., 2007b].