Joint two-dimensional observations of ground magnetic and ionospheric electric fields associated with auroral zone currents. 2. Three-dimensional current flow in the morning sector during substorm recovery.

Abstract

By using two-dimensional observations of ground magnetic perturbations with the Scandinavian Magnetometer Array and by incorporating some simultaneous electric field observations made by the STARE radars, an attempt is made to model the threedimensional current system in the late morning sector during a substorm recovery phase on February 16, 1977. During the recovery phase of substorm activity a localized region of net upward field-aligned current drifts to the east. This current is apparently carried by drift precipitation of energetic electrons which has been observed earlier by balloon and satellite spectrometers under the same geophysical conditions. The precipitating electrons responsible for the upward field-aligned current seem to shortcircuit the westward electrojet Hall current and cause its divergence up magnetic field lines. Equatorward of the auroral oval the precipitating electrons create a high-conducting channel where an eastward current is flowing. This current is probably a Cowling current and is decreasing in the eastward direction. While it remains open how this current is fed into the ionosphere, we content that the total eastward current is also diverging up magnetic field lines.

Ionospheric currents estimated simultaneously from CHAMP satelliteand IMAGE ground-based magnetic field measurements: a statisticalstudy at auroral latitudes

“…By comparing the results from the simple model with the difference of 10 to 15% derived by our correlation analysis we may conclude that the average induction effect associated with auroral electrojet in the IMAGE region is, on average, smaller. This is consistent with the findings of Baumjohann and Kamide (1981).…”

MLT and seasonal dependence of auroral electrojets: IMAGE magnetometer network observations

“…This suggests that most of these predominant features are mainly caused by the S q and current systems. The annual variations of the IU index in the MLT sector 0400–0800 might be associated with a dawn sector eastward current suggested by Baumjohann and Kamide []. This eastward current is flowing equatorward of the auroral oval in a conductivity channel created by the precipitating electrons.…”

Comparison of height‐integrated current densities derived from ground‐based magnetometer and rocket‐borne observations during the Porcupine F3 and F4 flights

“…Equivalent ionospheric current densities can be calculated from ground-based magnetometer measurements by means of upward field continuation [Mersmann et al, 1979;Baumjohann et al, 1979;Sulzbacher et al, 1980] or other modelling techniques [e.g., Akasofu et al, 1979Akasofu et al, , 1981Gough, 1977, 1978;Baumjohann et al, 1977Baumjohann et al, , 1981bBazarzhapov et al, 1976Bazarzhapov et al, , 1979Rostoker, 1977, 1979;Kamide et al, 1976Kamide et al, , 1981Kroehl and Richmond, 1979;Wallis, 1976]. In case additional ionospheric quantities like electric fields (available from, e.g., radar or balloon measurements) are simultaneously known, even the real ionospheric current system may be derived as done by, for example, Baumjohann [1979], Baumjohann and Kamide [1981], Baumjohann et al [1980Baumjohann et al [ , 1981a, Gustafsson et al [1981], and Inhester et al [1981].…”