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This paper presents the observations of ionospheric parameters in Kaliningrad (54&deg, N, 20&deg, E) during a meteorological storm in the Baltic Sea during October 2017 and 2018. Analysis of the total electronic content (TEC) during the storm showed that perturbations of the TEC values from the median can reach two standard deviations of the value. For the critical frequency of the F2 layer, it was 1.5&ndash, 1.6 times the standard deviations. On days of a meteorological storm, significant changes were noted in the dynamics of the E-layer&rsquo, s critical frequency. The reasons for the occurrence of the observed phenomena were due to the propagation of acoustic-gravity waves generated by convective processes in the lower atmosphere during periods of a meteorological storm. Spectral analysis of TEC variations revealed an increase in the amplitudes of ionospheric variations 10&ndash, 16 min over the area of a meteorological storm. The analysis allowed us to conclude that ionospheric perturbations during the meteorological perturbation were caused by increased acoustic-gravity wave (AGW) generation processes in the lower atmosphere. The most likely cause of negative ionospheric disturbances were processes associated with the dissipation of AGW propagating from the area of a meteorological storm and increased turbulence in the lower thermosphere.

The results of observations and modeling of the ionosphere parameters in periods of the severe troposphere weather events in October 2017, 2018 are presented. We analyze variations in the F2-layer critical frequency (foF2), in the total electron content (TEC), in the sporadic E-layer critical frequency during meteorology disturbances in the troposphere. It was shown that the meteorology storms can influence on the ionosphere parameters through the gravity waves (GWs). The GWs generated in the meteorology storm area can propagate into upper atmosphere and ionosphere. The GWs dissipation leads to the formation of disturbances in the thermospheric state at spatial scales that are determined by the duration and spatial dimensions of the region located in the meteorological disturbance zone. To interpret the observed disturbances in the upper atmosphere, the experimental measurements are compared with the results of model calculations obtained with the Global Self-Consistent Model of Thermosphere— Ionosphere—Protonosphere (GSM TIP).

The role of atmosphere aerosols in the global electric circuit, particularly during earthquakes preparation periods, is discussed in this review paper. Aerosols participate in production and transport of electric charges as well as in clouds formation. Satellite imagery shows increased aerosol optical depth over the tectonic faults and formation of the anomalous clouds aligned with the faults shortly before the earthquake shocks. At the same time variations of the ionospheric electric field and total electron content (TEC) are observed. We assume that the vertical electric current is generated over the fault due to the separation and vertical transport of charges with different masses and polarities. This charges the ionosphere positively relative to the Earth in the same way as the thunderstorm currents do. The resulting electric field in the ionosphere drives F2-layer plasma via the electromagnetic [ E → × B → ] drift and decreases or increases electron density depending on the configuration of the electric field, thus, creating observed negative or positive TEC disturbances. The important role of the electric dynamo effect in these processes is underlined.

Herein, we analyze the variations in the ionosphere for the period of two weeks before the M6.7 earthquake in India on January 3, 2016. The earthquake occurred after a series of magnetic substorms on December 31, 2015 and January 1, 2016. The relative total electron content (TEC) disturbances have been estimated using global TEC maps and calculated numerically using the 3D global first-principle Upper Atmosphere Model (UAM) for the whole period including the days before, during, and after the substorms. Numerical simulations were repeated with the seismogenic vertical electric currents switched on at the earthquake epicenter. The UAM calculations have reproduced the general behavior of the ionosphere after the main phase of the geomagnetic storm on January 1, 2016 in the form of negative TEC disturbances propagating from high latitudes, being especially strong in the Southern (summer condition) Hemisphere. It was shown that the local ionospheric effects of seismic origin can be identified in the background of the global geomagnetic disturbances. The seismo-ionospheric effects are visible in the nighttime regions with the additional negative TEC disturbances extending from the eastern side of the epicenter meridian to the western side, both in the observations and in the UAM simulations. It was found that the vertical electric field and corresponding westward component of the electromagnetic [E &times, B] drift played a decisive role in the formation of the ionospheric precursors of this earthquake.

The results of simulation of ionospheric total electron content (TEC) caused by the electric field induced by an electric current between the Earth and the ionosphere are reported. The calculations are performed using a model of the upper atmosphere of the Earth (UAM). The equation for the electric potential in the UAM is solved by specifying vertical electric currents in a limited area of the lower boundary of the ionosphere, presumably over the epicenter of a forthcoming earthquake. The dependence of the intensity of TEC disturbances on the electric current direction, latitudinal location of the sources, and their configurations is examined. The most intense TEC disturbance are predicted when the sources are located within 30°–45° geomagnetic latitude. Simulating the concurrent action of vertical currents and compensating “return” currents uniformly distributed around the globe outside the region of “direct” currents showed no significant changes in the TEC disturbances compared with the situation where merely “direct” currents are considered. The role of the vertical and horizontal components of the electromagnetic drift of ionospheric plasma in the variations of the electron density in different areas relative to the electric current source is discussed.

Recent ionospheric observations report anomalous total electron content (TEC) deviations prior strong earthquakes. We discuss common fetures of the pre-earthquake TEC disturbances on the basis of statistics covering 50 strong seismic events during 2005-2006. The F2-layer ionospheric plasma drift under action of the electric fields of seismic origin is proposed as the main reason of producing TEC anomalies. The origin of such electric fields is discussed in terms of the lithosphere-atmosphere-ionosphere coupling system. This theory is supported by numerical simulations using global Upper Atmosphere Model (UAM). UAM calculations show that the vertical electric current with the density of about 20 - 40 nA/m2 flowing between the Earth and ionosphere over an area of about 200 by 2000 km is required to produce the TEC disturbances with the amplitude of about 30% - 50% relatively to the non-disturbed conditions. Ionosphere responses on the variations of the latitudinal position, direction and configuration of the vertical electric currents have been investigated. We show that not only the vertical component of the ionospheric plasma drift but also horizontal components play an important role in producing pre-earthquake TEC disturbances.