Small-Scale Plasma Irregularities in the Ionospheric D Layer

Taking into account the vertical current in the Earth's atmosphere and rejecting the frequently used quasineutral plasma approximation, which is wrong in the given case, the existence in the ionospheric D layer of thin plane regions with a characteristic size of ~1 m in which the plasma density increases abruptly with altitude is shown. Especially strong variations in the plasma density occur in the equatorial ionosphere, where the geomagnetic field is horizontal. The magnitude of the plasma density jump strongly depends on the electric field E at the lower boundary of the layer. In particular, at E = 0.1 V/m and an altitude of 85–90 km in the equatorial ionosphere, the plasma density jumps by a factor of 3.6, while at E = 0.2 V/m, by a factor of 15.5. A mechanism for the emergence of ionospheric precursors of earthquakes associated with the presence of such a jump is offered.