Abstract
For more than two decades numerical models of the Earth's magnetosphere have been used successfully to study magnetospheric dynamic features such as the excitation of ULF pulsations and the mechanism of field line resonance. However, numerical formulations simplify important properties of the real system. For instance the Alfvén continuum becomes discrete because of a finite grid size. This discretization can be a possible source of numerical artefacts. Therefore a careful interpretation of any observed features is required. Examples of such artefacts are presented using results from a three dimensional dipole model of the magnetosphere, including an inhomogeneous distribution of the Alfvén velocity.
Highlights
The Earth's magnetospheric system cannot be described by analytical models in all of its complexity
A well-studied aspect of magnetospheric physics is the theory of magnetohydrodynamic (MHD)
The physical parameter that changes with the grid size and that can be related to the wave modes is the dierence of the eigenfrequencies Df of the radially neighboring ®eld lines
Summary
The Earth's magnetospheric system cannot be described by analytical models in all of its complexity. The physical parameter that changes with the grid size and that can be related to the wave modes is the dierence of the eigenfrequencies Df of the radially neighboring ®eld lines.
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