SIMULATION STUDIES OF IONOSPHERIC ELECTRIC-FIELDS AND CURRENTS IN RELATION TO FIELD-ALIGNED CURRENTS .1. QUIET PERIODS

Computer simulation studies of the electric fields and currents in the global ionosphere produced by field-aligned electric currents for quiet periods are conducted. The steady state equations for current conservation are solved numerically. Resultant computer-plotted diagrams include equipotential contours of the electric fields, vector distributionS of the electric fields and currents, and electric current patterns equivalent to the magnetic field effect produced by the field-aligned and real ionospheric currents. One of the merits of this simulation method is that the three-dimensional current system can roughly be estimated from the equivalent current system obtained from ground-based geomagnetic data alone. This paper also provides a foundation for a similar study of substorms. The results are discussed.