Equatorial electrojet phenomenon

Evidence has been discussed showing: that the ionospheric current system is basically in two layers; that the upper current layer peaking over the dip equator at 136±8 km altitude is likely the worldwide part of Sq; that the lower current layer peaking at 106 km altitude is likely the equatorial electrojet (EEJ); and that the EEJ returns close by the flanks of the dip equator. As the first contours of the worldwide part of Sq have now been presented, some of its parameters are compared with those of the EEJ. The ratios of the internal to the external parts of the EEJ magnetic field components are given as: H_i/H_e, 0.28±0.08, Z_i/Z_e, −0.17±0.02, F_i/F_e, 0.23±0.02. The ratio AF/AH, of the difference field on penetrating the ionospheric current layers to their horizontal magnetic field on the ground decreases from about 2.4 at the dip equator to about unity towards the EEJ current focus at about 3° dip latitude. New proposals capable of explaining the observed features and mechanisms of the equatorial counter electrojet have been presented.