Counter-electrojet and Esq disappearance

摘要: Abstract The disappearance of Esq type traces from ionograms at the magnetic equator during magnetically quiet periods is related to inverted latitudinal profiles regular daily SR variation (in its horizontal and vertical components). Latitude obtained a meridian chain nine magnetometers across central Africa are compared with corresponding quarter-hourly ionogram sequences Fort-Archambault-Sarh (Chad). Between 0900 1500 LT, reversal coincides exactly traces. This evidence gives additional weight hypothesis counter-electrojet current belt, located on same latitudes as normal electrojet probably flowing below it bottom E-layer. It agrees well present theory II slow turbulent modes, confirms VeΛB plasma instability mechanism cause inhomogeneities this level.