Some remarks on the equatorial sporadic E layer at Kodaikanal

It is shown that the sporadicE layer at an equatorial station is not always of the commonly known equatorial (q) type Es. Broadly there occur two types of Es at a station near the magnetic equator,viz., (i) diffuseq type and (ii) multiple or blanketing (b) type. The latter may be of diffuse type or of thin layer type. The Es-b is due to highly dense cloud of ions which are localised, whereas Es-q occurs over an extended area at any time. The effect of counter-electrojet is seen on both the types of Es layers. The disappearance of sporadicE during counter-electrojet is valid for only theq type of Es, but sometimes Es-b may occur during periods of very weak or reversed electrojet. It is suggested that published equatorial Es data should be used with caution unless the type of Es is also indicated. The plausible causes of the sudden disappearance of Es-q on some occasions and the appearance of Es-b during others are suggested