F-region Drift Measurementsat Tiruchirapalli

31-35Ionosheric drift measurements were conducted at the equatorial station Tiruchirapalli (dip 4.8ᵒ N) since 1972. The F-region drifts during 1973-75 were observed to be predominantly westward during daytime with mean speed of about 100 m/sec and eastward during nighttime with mean speed of about 70 m/sec. The daily variation of the mean drift speed showed a peak around 1000 hrs local time. The maximum daytime drift speed showed semi-annual variation with maxima in equinoxes while its time of occurrence showed an annual variation with peak occurring late during summer months. Comparison with the earlier results at another equatorial station, thumba, showed similarity in all aspects excepts that the drift speed at Tiruchiraplli are smaller as compared to that at Thumba. Thus the ionospheric drift at Tiruchirapalli is found to be associated with equatorial electrojet