Effect of Geomagnetic Storms (Substorms) on the Ionosphere: 1. A Review

The result of the effect of magnetospheric storms and substorms on the ionosphere (the so-called main effect) has been studied. The effect consists in that the critical frequency and altitude of the F region vary specifically during a disturbance. The critical frequency first increases before the storm (substorm) active phase, then decreases during the active phase, and increases again after this phase. On the contrary, the F region altitude increases during the active phase and decreases after this phase. An approach to the short-term (2-3 h) prediction of the development of storms (substorms) as the main disturbed space weather elements has been proposed.