Air Current Circulation as a Possible Cause of Preseismic Anomalies in the Surface Electric Field

Abstract

Ground-based measurements of the vertical atmospheric electric field of the Earth sometimes show bay-like anomalies that precede certain 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 electrical conductivity in the surface air and increased radon emission from the soil. This paper proposes another mechanism of atmospheric electrical anomalies that involves the entrainment of charged aerosols and light and heavy ions by air flows. Such flows can be produced by small temperature anomalies observed before some seismic events. Theoretical analysis shows that anomalously strong electrical variations may occur even in the presence weak air flows provided that they persist for a long time and there is a specific structure of the velocity field with vertical air circulation and particle exchange between different atmospheric layers. For this type of flows, an analytical 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 observational data.