Concerning the conjugation of field-aligned currents

Abstract

It is known that the combined action of convection and pitch-angle diffusion is responsible for the formation of gas pressure distribution in the magnetosphere. Plasma pressure, in turn, determines - within the framework of a given magnetic field model - the density of bulk currents in the magnetosphere. With a knowledge of the bulk currents as a function of coordinates, we can calculate the field-aligned currents as a divergence of bulk currents. On the other hand, specifying the convection model is equivalent to specifying the electric field model. Since within the approximation of equipotential field lines the electric field is common to the magnetosphere and ionosphere, bulk currents and field-aligned currents in the ionosphere can be formally calculated subject to the condition that ionospheric conductivity is wholly determined by electron precipitation from the magnetosphere. The precipitation intensity is readily inferred from the same magnetospheric model. Thus we have two systems of field-aligned currents. One system is calculated from the model of plasma pressure distribution in the magnetosphere, and the other is inferred from a given model of the electric field and the electroconductivity model calculated from electron precipitation. This brings up the question: How can these two systems of field-aligned currents be reconciled? From previous studies it is known that magnetospheric convection "adjusts itself" to the level of energy losses in the ionosphere. Based on this, an attempt can be made to achieve a conjugation of the aforementioned two systems of field-aligned currents. This paper is devoted to analyzing such an attempt.