Events of 2 August 2002. 1. Features of field-aligned currents of a substorm

[1] A model of alignment of the field-aligned current generator system in the disturbed magnetosphere has been proposed. It has been found that main Pedersen currents in the disturbed ionosphere of the auroral oval are meridional, joining opposite field-aligned currents of two neighbouring regions of Iijima and Potemra. This fact complements the central concept of current in which the current wedge plays a leading part. We have obtained curves of field-aligned current intensity in each of the three regions of Iijima and Potemra in the Northern hemisphere during the substorm considered. These new data imply that intensities of the region 1 field-aligned current and the sum of the regions 1 and 2 field-aligned currents remain equal during a disturbance. The equality means that the said three generators make up a unified system. We have also revealed inequalities between two field-aligned currents of different sign simultaneously observed in dawn and dusk sectors in each IP regions. A conceptual model of formation of the said dawn-dusk asymmetry has been put forward. It includes field-aligned currents joining two hemispheres in addition to those closing in the ionosphere of the Northern hemisphere. The conclusion that the global magnetospheric dynamo works as a voltage generator under quiet (moderate) conditions as well as during storms has been justified.