The latitudinal distributions of auroral zone electric fields and ground magnetic perturbations and their response to variations in the interplanetary magnetic field

Abstract

Chatanika observations of latitudinal distributions of convection electric fields (E⊥) are compared with isointensity ΔH contours in latitude and time from the Alaskan magnetometer chain and with the north‐south component of the interplanetary magnetic field (IMF Bzm) from Imp‐J. As expected, northward electric fields were generally observed within latitude and time regions where ΔH was positive, while southward electric fields were observed within negative ΔH regions. However, correlation between the magnitudes of the electric fields and of the ΔH perturbations was not strong, owing to variability in ionospheric conductivities produced by precipitation and solar illumination. In the midnight sector the northward‐to‐southward transition in the electric field and positive‐to‐negative ΔH transition were roughly collocated (to within 1 hour in local time) as signatures of the Harang discontinuity. The most important findings are that (1) southward (northward) IMF Bzm transitions caused rapid equatorward (poleward) shifts of the electric field and ΔH patterns and (2) southward IMF Bz transitions, magnetospheric substorms, and local time transitions of the Harang discontinuity can all lead to northward‐to‐southward transitions of the electric field in the midnight sector. Due to the interlaced phasing of each of these three causal mechanisms a highly complex temporal pattern of electric fields results.