Large-Scale Disturbances Features Induced in the Ionosphere by Powerful Decameter Radiation during Moderate Magnetic Storms

The paper presents the results of experimental studies of aperiodic and quasi-periodic disturbances in the ionosphere that were observed under the influence of powerful radiation from the SURA facility on the ionospheric plasma in quiet and magnetically disturbed conditions. A vertical Doppler sounding radar located at a distance of ~960 km from the heating facility was used for diagnostics. The recorded aperiodic disturbances with a delay of ~25 min are most likely associated with the generation of a shock-wave disturbance related to atmospheric gravity waves. Quasiperiodic disturbances of 12–15 min had a period equal to the period of the heating cycle. In other cases, the period of disturbances was equal to the period of natural oscillations of the air in the atmosphere. The speed of quasi-periodic disturbances was 300–400 m/s. The effects of the artificial generation of plasma turbulence, the joint action of solar terminator and powerful radiation, and the resonance effects associated with the impact of radio waves with a frequency equal to the fourth harmonic of the electron gyrofrequency on the ionosphere are found. The role of magnetic activity in the Earth–atmosphere–ionosphere–magnetosphere system, which determined the nature of disturbances in the ionosphere, is noted.