The first observations of mean winds and the amplitude and phases of the tidal components measured with a meteor wind radar located at Trivandrum (8.5°N, 77°E) during five consecutive days of counter electrojet events identified in the horizontal component of the earth's magnetic field from January 27–31, 1987 are described. The mean zonal winds in the altitude region of 90–105 km are in general westward during counter electrojet days and eastward during no counter electrojet days. The amplitudes and phases of the tidal components on the counter electrojet days are found to be substantially different from those on the no counter electrojet days.

The electric fields engendered by winds of gravity wave origin are theoretically calculated for the dynamo region of the equatorial ionosphere. A general expression for the efficiency parameter, which is a measure of the effectiveness in producing the total electric field, is derived for a two‐dimensional case, and the results are compared with those obtained from the one‐dimensional treatment of the problem by Kato (1973). The efficiency parameter evaluated by Kato (1973) at the center of the electrojet is higher by about a factor of 5 than that computed here, owing to some approximations made by him. The dependence of the efficiency parameter on the horizontal scale size of the gravity wave wind and the effectiveness of the east‐west wind shear in producing the electron density stratifications are discussed.

[1] The characteristics of different types of Sporadic E (E S ) layers and the associated plasma density irregularities over the magnetic equator have been studied in a campaign mode using VHF backscatter radar, digital ionosonde, and ground magnetometer data from Trivandrum (dip latitude 0.5°N, geographic latitude 8.5°N, geographic longitude 77°E), India. The presence of blanketing type E S (E Sb ) in the ionograms with varying intensity and duration were observed in association with afternoon Counter Equatorial Electrojet (CEEJ) events. E Sb was associated with intense backscatter returns and with either very low zonal electric field and/or with distortions present in the altitude profile of the drift velocity of the type II irregularities. The results of the coordinated study indicate the possible role of vertical electron density gradients in E Sb layers in addition to providing evidence for the local winds to be responsible for the vertical gradients themselves.

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