Characteristics of equatorial electrojet over India determined from a thick current shell model

For the first time the five parameters required to fully describe Onwumechili’s composite thick current shell model format of equatorial electrojet have been evaluated from a single autonomous set of ground data at solar minimum. The thick current shell model, which takes into account the vertical ionospheric currents, permits both the width and the thickness of the jet to be determined simultaneously. The mean annual values of the electrojet parameters evaluated over India sector are: the peak intensity of the forward current at its centre, 62.97±2.73 A/km; the peak intensity of the return current, 19.43±2.49 A/km; the ratio of the peak return to the peak forward current intensity, 0.312±0.052; the total forward current flowing between the current foci, 19.01±1.74 kA; half of the latitudinal width or the focal distance from the current centre, 2.7±0.18°; the distance of the peak return current location from the current centre, 5.31±0.19°; the half thickness of the peak current density, 0.063±0.003°; the latitudinal extent of the current from its centre, 9.25±2. 08°; and the dip latitude of the equatorial electrojet EEJ centre −0.190±0.003°. The dip latitude of the centre of EEJ exhibits a consistent northward migration towards the dip equator from the rising of the jet at dawn from an annual average of −0.193° to about −0.186° at about 1100 h LT, after which it begins to recede southward towards the dusk. Our results show that the electrojet becomes more (less) intensified as the centre of the electrojet moves northwards (southwards) towards (away from) the dip equator. The diurnal variation of the thickness of the EEJ is opposite that of its current intensity and half width. The thickness of equatorial electrojet EEJ exhibits a consistent diurnal variation such that it decreases from about 0.066° at dawn to the minimum at about 1100 h LT and then begins to increase towards the dusk. The wider (thicker) the EEJ, the stronger (weaker) the EEJ strength. The order of seasonal variation of the mean daytime current intensity Jo and forward current Ifwd is E>D>J. However, the diurnal variations of the EEJ parameters exhibit seasonal dependence as the order of seasonal variation is not uniform at every hour of daytime for all the parameters.

► Full characteristics of EEJ were derived from an empirical model.
► Parameters of the EEJ tallied with satellite and rocket observations.
► Dip latitude of centre of EEJ is closer to dip equator at peak intensity period.
► Diurnal variation of the thickness of the EEJ is opposite of its current intensity.
► The wider the EEJ, the stronger the EEJ strength.