Automated Regional Modelling (ARM) for characterization of the substorm current wedge

Abstract

Some characteristics of substorms may be determined through use of an electrojet forward modelling approach. These include the amplitude of cross-meridian electric current (0.2 to 1 MA typically), timescales (about 20 minutes to peak current and poleward extension), and amount of poleward motion (several degrees). An increase in the number of magnetic stations deployed in North America makes use of a full substorm current wedge system possible, reproducing well the perturbations observed both in the auroral zone and at subauroral stations. This provides good characterization not only of the aforementioned parameters, but also of the substorm longitudinal parameters including the central meridian. In principle, extension of near-Earth field-aligned currents into space is possible based on inversion results and field models. In practice, comparison with data from spacecraft such as THEMIS is complicated by processes in space such as plasma sheet changes at substorm onset