Influence of Conductivities Consistent with Field-Aligned Currents on High-Latitude Convection Patterns

摘要

The influence on high-latitude ionospheric convection of conductivities associated with upward field-aligned currents is investigated. Potential patterns are calculated from a given distribution of field-aligned currents and a conductivity model. The resulting patterns are shown to be modified considerably by including a coupling term between the conductivity and the field-aligned current in the conductivity model. The clockwise rotation of the entire potential pattern is reduced when the conductivity enchancement coincides with the regions of upward field-aligned current. The electric field within these regions is rather insensitive to changes in the magnitude of the current. In regions of downward current or when the current-dependent conductivity is excluded there is on the other hand an almost linear relationship between current and electric field. Although the particles producing the conductivity enhancement may not be the same as those carrying the major part of the field-aligned current, it is clear from observations that there is a positive correlation between upward current and conductivity. Therefore, the simple relationship used reflects well the principal features of the current-conductivity coupling, which is of importance to the modeling of ionospheric electrodynamics.