HORIZONTAL DRIFTS IN E-REGIONS AND F-REGIONS OVER THUMBA, DURING DAY-TIME

The paper describes the apparent horizontal drifts in theE- and F-regions of the ionosphere over Thumba, India (dip. 0.6°S) during the day-time hours of the years 1964-1967. The direction of drift is predominantly towards west (about 80 per cent of occasions during any of the seasons of the year). The speed of drift is found to be larger than at any other equatorial stations for which the data are available. The diurnal variation of drift speed in E- or F-regions shows a forenoon maximum which occurs later during June-July, than during other months. There is no distinct change in the drift speed or direction between the years 1964-1967. A comparison of drift speed at other stations shows minimum at mid-latitudes and a sharp maximum over the magnetic equator. Drift observations at other low latitude stations are recommended for a detailed study of the abnormal zone near the magnetic equator. © 1969.