Field line resonances in discretized magnetospheric models: an artifact study

Abstract

For more than two decades numerical models of the Earth’s magnetosphere have been used success- fully 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 Alfveén continuum becomes discrete because of a finite grid size. This discretization can be a possible source of numerical artifacts. Therefore a careful interpretation of any observed features is required. Examples of such artifacts are presented using results from a three dimensional dipole model of the magne tosphere, including an inhomogeneous distribution of the Alfveé n velocity.