Air Flow Circulation as a Possible Cause of Preseismic Anomalies in the Near-Surface Electric Field

Ground-based measurements of the vertical atmospheric electric field of the Earth sometimes show bay-like anomalies that precede some earthquakes. In some cases, these anomalies have even been accompanied by a change in the sign of the field under fair weather conditions. Possible causes of this phenomenon are typically attributed to anomalous changes in the electrical conductivity in the near-surface atmospheric layer, increased radon emission from the soil, etc. This paper proposes another mechanism of atmospheric electrical anomalies, which involves the entrainment of charged aerosols as well as light and heavy ions by air flows. Such flows can be produced due to small temperature anomalies observed before some seismic events. Theoretical analysis shows that anomalously strong electrical variations may occur even in the presence of weak air flows provided that they persist for a long time and a peculiar structure of the velocity field, which presumes vertical air circulation and particle exchange between different atmospheric layers. For this type of flows, an analytic solution is derived and spatial distributions of atmospheric electric perturbations are obtained. The results of calculations and estimates confirm that the proposed mechanism can explain the observation data.