A study of blanketing sporadic E in the equatorial region

Ionosonde data, obtained on blanketing sporadic E at some equatorial stations during the I.G.Y. have been analysed to yield temporal and latitude variations. The results are compared with corresponding ones for the middle latitudes and they are also discussed in the light of the wind-shear mechanism. The main features of the occurrence frequency are (i) the absence of a morning peak in the daily variation, (ii) an equinoctial maximum and a June-solstitial minimum, (iii) and a stronger dependence on the dip angle (or geomagnetic latitude) than on geographic latitude. The latitude variation obtained also suggests that blanketing sporadic E would occur over both the dip and geomagnetic equators.