Formation of Sporadic <i>E</i> Layers at Temperate Latitudes Due to Vertical Gradients of Charge Density

Abstract

Applying the method of instability analysis of weakly ionized plasmas, it is shown that the ionosphere at the height 100–120 km at temperate latitudes is capable of producing irregularities in charge density in the presence of vertical gradients of background charge density, external electric and geomagnetic fields. Worldwide distribution of local time versus geomagnetic latitudes where ƒ 0 E s exceeds 5 Mc/s is compared with that theoretically predicted. Results obtained seem to be an evidence that such a mechanism, other than that of wind shear, is also responsible for the formation of sporadic E at temperate latitudes.