Equatorial anomaly in ionospheric electron content and its relation to dynamo currents

Abstract

Using the ATS 6 satellite radio beacon data collected over a chain of stations in the Indian zone, a study has been made of the equatorial anomaly in total electron content (TEC) and its relation to the E region currents. Two parameters, ΔHd, the difference in the magnetic field perturbation between the equator and a low‐latitude station, and Vd, the backscatter radar measurement of the draft velocity of the electrojet irregularities, are used to represent the equatorial current strength. The results, presented in the form of regression plots relating the strength of the anomaly and that of the current, indicate that the anomaly dependence on the current strength is about the same for all the three seasons. It is also noted that, regardless of the season, the anomaly crest moves toward a farther latitude from the equator with increasing current strength. The total ionization inventory, Σ TEC, of the anomaly belt is found to increase linearly with the strength of the equatorial current and this result seems to bear some significance for the correlation observed between TECmax and ΔHdmax at the equator.