Effect of equatorial electrojet on electron content variations at two longitudinally separated low latitude stations

Abstract

Total ionospheric electron content (IEC) obtained simultaneously at two low latitude stations, Udaipur (22.6 °N, 69.6 °E, dip latitude 14.4 °N) and Gauhati (23.8 °N, 83.6 °E, dip latitude 14.2 °N) during solar minimum has been analyzed to investigate the effect of equatorial electrojet and spatial separation. Results show that the mean peak levels of ionization in winter and summer are about equal at Gauhati whereas at Udaipur winter IEC is less than that obtained in summer. The difference in solstitial behaviour was brought about by reduction in the winter level of ionization at Udaipur compared to that at Gauhati. Diurnal and seasonal variations of IEC at these two locations under the influence of strong equatorial electrojet (EEJ) were found to be dissimilar as a result of which difference between the two sets of data increases. Latitudinal variation of IEC as derived from observations along a chain of stations centered around 71 °E meridian in the Indian low latitude region shows that the position of the crest of the anomaly varies with season but not with the strength of EEJ. IEC for Gauhati does not correspond to the anomaly level along 71 °E indicating a longitudinal variation within the Indian zone.