Spherical Elementary representation of ionospheric equivalent currents: results from a test model.

The auroral electrojet, and associated current systems are an important source of the magnetic field observed on the ground, and in space. In main magnetic field modelling we'd like to minimise the influence of such non-uniform current systems. This is usually done using careful date-selection based on indices. Ionospheric equivalent currents derived independently from the ground and the CHAMP satellite have been shown to be in good agreement (Ritter et al. 2004). This offers the possibility of a non-index based data selection e.g. by estimating the ionospheric current density as a function of time and space ground based observatory data, and then selecting suitable time intervals for modelling. We present the results of our implementation of fitting Spherical Elementary Current Systems (SECS) to a model of the auroral electrojet based on a simple line-current.