Dependence of the Equatorial Electrojet on Auroral Activity and In Situ Solar Insulation

摘要

By using 10 years of Challenging Minisatellite Payload satellite observations, we investigate the average conditions of the interplanetary magnetic field (IMF) prevailing during the westward counter equatorial electrojet (CEJ). Equally, we compared the average IMF conditions accompanying high-latitude field-aligned currents of the Region 1 (R1) and Region 2 (R2). It shows that both CEJ and high-latitude field-aligned currents events when R2 is greater than R1 tend to happen preferably during the northward turning of the IMF Bz and the substorm recovery phase. Sunlight has an important influence on the longitudinal distribution of the equatorial electrojet (EEJ), and the effect is opposite to the tidal electric field at E region. The anticorrelation between cos~(0.5)(SZA) (solar zenith angle effect) average values during CEJ events and EEJ intensity is most prominent around June solstice. By using combined measurements from Challenging Minisatellite Payload and DMSP satellites, it is found that before the occurrence and in the initial phase of a subauroral polarization stream the EEJ gets enhanced, and after about 30 min it reduces in intensity. The CEJ occurrence rate more than doubles during subauroral polarization stream periods compared to normal conditions.