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The variations of the ionospheric current in the lower ionosphere and the plasma density of the upper ionosphere have been studied based on the monitoring of the horizontal component of the geomagnetic field induction and height-frequency sounding of the critical frequency of the ionosphere F layer at the Moscow Observatory. It is shown that, in the spectra of time variations of the geomagnetic field and the critical frequency of the F2 layer in the range of planetary waves in winter, there are both harmonics associated with solar activity and harmonics corresponding to quasi-5-, 10-, and 16-day planetary waves. The involvement of geomagnetic field registration data for a 20-year time interval (from 2001 to 2020) have made it possible to identify more subtle effects, namely, the harmonics associated with the modulation effect of longer period variations and tidal effects are identified. [ABSTRACT FROM AUTHOR]

Based on the analysis of data from the Geophysical Observatory "Mikhnevo" and the Center for Geophysical Monitoring of Moscow of the Institute of Geosphere Dynamics of the Russian Academy of Sciences, the response of the atmospheric boundary layer to the strong earthquakes with magnitudes starting from ≥7 is considered. It is shown that the Tohoku earthquake (March 11, 2011, Japan) can be associated with the variations in atmospheric pressure with periods ranging from 8 to 11 h that emerged after this event, whereas a series of the strong earthquakes discussed in the work are accompanied by the variations in the atmospheric pressure with periods close to the singlets of the fundamental free oscillation of the Earth 0S2. Another effect after the earthquakes is the presence of the acoustic-gravity waves in the atmosphere with a period close to the Brunt-Väisäla period at large distances from the epicenter. [ABSTRACT FROM AUTHOR]