Simulation studies of ionospheric electric fields and currents in relation to field-aligned currents, 2. Substorms

摘要: Computer simulation studies of the electric fields and currents in global ionosphere produced by field-aligned for quiet periods are conducted. The steady state equations current conservation solved numerically assuming (1) several divided regions earth (such as polar cap, auroral zone, middle-low latitudes), (2) exponentially distributed anisotropic conductivities each zone with a continuous change at boundaries regions, (3) downward upward intensities region, assumptions based on our knowledge phenomena geomagnetic variations well rocket satellite measurements currents. Resultant computer-plotted diagrams include equipotential contours fields, vector distributions currents, patterns equivalent to magnetic field effect real ionospheric One merits this method is that three-dimensional system can roughly be estimated from obtained ground-based data alone. This paper also provides foundation similar study substorms. following main results obtained: Conductivity inhomogeneity alters considerably pattern has previously been uniform conductivity distribution. Even slight enhancement along nightside belt large modification field. existence strong gradients equatorward half oval reduces middle low latitudes. corresponds ‘shielding’ inside Alfven layer magnetotail. (4) Seasonal changes cap cause surprisingly effects (5) differ significantly both intensity direction.