On the seasonal variation in the temperate Es occurrence

Abstract

The seasonal variation in the occurrence of sporadic- E measured by ionosondes in temperate northern and southern latitudes during a 6-yr period, is compared with the seasonal variation of the zonal wind system and with meteor activity over both hemispheres. This comparison shows that changes of the zonal wind system are the determining factor in the seasonal variation of the occurrence probability of Es; changes in content of the meteoric matter are not decisive, but the presence of this matter is a necessary condition for an . Es-layer to be formed.