Modeling of local disturbance formation in the ionosphere electron concentration before strong earthquakes

Abstract

In the past numerical experiments had shown that local disturbances of zonal electric fields allow reproducing the morphology of ionospheric disturbances during seismic active periods. In these numerical experiments the physical processes leading to the formation of such electric fields were not discussed. This paper offers two potential formation mechanisms of ionospheric precursors based on (1) the propagation and dissipation of small-scale internal gravity waves (IGWs) in the upper atmosphere, and (2) the penetration of a vertical electric field from the atmosphere into the ionosphere. We have simulated the effects of small-scale IGWs and the penetration of a vertical electric field for a mid-latitude earthquake in Greece using the Global Self-consistent Model of the Thermosphere, Ionosphere and Protonosphere (GSM TIP). It is shown that the simulation results obtained with the IGWs hypothesis are in good qualitative agreement with GPS TEC data. The simulation results obtained with the vertical electric field hypothesis are in less good agreement with GPS TEC data.