Аннотация:The question of whether earthquake precursors can arise in the ionosphere is of a special interest ingeophysics. Despite numerous encouraging reports on seismo-ionospheric effects, the mechanism ofthe lithosphere-atmosphere-ionosphere coupling (LAIC) during the crust destruction phase was notrevealed yet. One of hypothesis assumes that a seismogenic current transfers an abnormal electricfield from the near-surface atmosphere to the ionosphere prior to an earthquake occurrence. Thiscurrent can be caused by the air ionization due to enhancement of radon gas emission from thesoil or upward movement of charged atmospheric aerosols. Here we present a theoretical modelof the spatial structure of the electric field in the atmosphere and bottom ionosphere driven by avertical extrinsic current in the lower atmosphere. Perturbation of electric field in the ionospherehas been derived in the approximation of the “thin” E-layer. Simple analytical estimates havebeen obtained that relate the horizontal electric field in the ionosphere, vertical electric field onthe ground, and parameters of the external current. The electric field attenuation with altitude iscaused by the increase of atmospheric conductivity and the horizontal spreading of current. Theestimates obtained enable one to evaluate the feasibility of anomalous variations of electric fieldsin the ionosphere related to forthcoming earthquakes. The analysis has shown that the hypothesison aerosol upward convection as a cause of ionospheric anomalies seems unrealistic. To interpretthe occurrence of significant ionospheric anomalies it would be necessary to assume the presence oftoo large currents and electric fields in the lower atmosphere that had never been observed duringnon-thunderstorm periods.
