Reduction and interpretation of ionospheric sounding ionograms from extremely low satellite orbits

Previously unknown phenomenon was detected during the ionospheric radiosounding on board the MIR space station when the station was below the F region maximum. The work is devoted to describing the most general properties of this phenomenon in terms in concepts prescribed by the URSI Handbook of ionogram Interpretation and Reduction in order to consider and analyze the phenomenon using the known categories and concepts of this handbook.