Modeling of field-aligned currents produced by asymmetric ring current during strong magnetic storms

The modeling of field-aligned currents (FACs) produced by an asymmetric ring current is presented. Our first results of the modeling of FACs in the magnetosphere, which were based on the theory advanced in [1–5], were obtained in [6]. It was shown that FACs develop as spiral structures. Extending this work, we came to the conclusion that FACs, appearing in the magnetosphere and ionosphere as a result of ion or electron injections, generally develop as clockwise (ion injections) or anticlockwise (electron injections) spirals that are independent of the number and energy spectra or space distributions of injected particles. A sharp maximum of FACs or an FAC jet in such spirals can be present at middle latitudes. The value of currents in a midlatitudinal FAC jet during strong magnetic storms and substorms could be of the same order as experimentally observed in the polar region. The model presented describes the dependence of ion FACs as well as FAC jets in the magnetosphere and ionosphere, on the parameters of injected particles.