Rapid changes of the outer high-latitude ionosphere combined with a penetration of intensive ULF (Pcl) signals

Variable values of the Pcl signal transmissivity through the ionosphere, experimentally obtained from the conjugated ULF experiment GEOS-1-Husafell during a roughly 1-h interval of the micropulsation disturbance on 13 July 1977, have been compared with the results of numerical simulation. Variations of the basic physical parameters of the high-latitude outer ionosphere have been considered. Quantitative estimates of the rapid changes of the ionized particle concentration in connection with the considered changes of the ionospheric plasma temperature have been made. It is assumed that the ioncyclotron waves themselves propagating along the plasmapause give rise to the non-stationary conditions in the outer high-latitude ionosphere ( Φ≈ 70°).