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The response of the lower ionosphere to the passage of several dozen typhoons has been studied using a regional network of VLF stations in the Russian Far East. The experimental data presented in all cases clearly demonstrates wavelike disturbances of the subionospheric VLF signal amplitude and phase during the active stage of typhoons crossing radio paths. With the exception of magnetoactive and seismoactive days, this means that the disturbances generated by a typhoon, when propagating into the upper ionosphere, pass through the lower ionosphere, causing corresponding disturbances in the amplitude and phase of the VLF signal. Spectral analysis shows that the range of the wave disturbances detected corresponds to the periods of atmospheric internal gravity waves (IGW). A mechanism of the action of IGWs on the lower ionosphere is proposed which allows us to interpret the VLF signal phase variations observed. According to this mechanism, the action of IGW on the lower ionosphere is caused by polarization fields arising during the wave motion of plasma in the lower part of the F layer. These fields projected along geomagnetic field lines into the lower ionosphere cause the upper wall of the Earth—ionosphere waveguide to rise or fall.

Abstract—The results of calculations of the magnetic field structure in the kinematic approximation are presented, testifying to the consistency of the constructed numerical model with the structure of the flows of a conducting liquid: the instability of the convective process in a rotating spherical shell is reflected in the evolution of the magnetic field, manifesting itself in the pulsation regime of the field. It is shown that the features of the field evolution in the calculations are most clearly pronounced at high latitudes and have analogs in the behavior of the real geomagnetic field. [ABSTRACT FROM AUTHOR]

Abstract—The use of a special technique for processing variations of the geomagnetic field at several mid-latitude observatories allowed us to identify a series of jerks over a 17-year period, from 2004 to 2020. To interpret the our experimental results showing that jerks follow with a quasi period of 3‒4 years, a probable mechanism of the occurrence of rapid changes in the geomagnetic field caused by unstable processes in the Earth's core is proposed. [ABSTRACT FROM AUTHOR]