The Influence of the Magnetic Field Inclination on the Quasistationary Electric Field Penetration from the Ground to the Ionosphere

Abstract

A quantitative model of the penetration of a quasistationary electric field from the Earth’s surface into the ionosphere with an inclined magnetic field is developed. A two-dimensional model is constructed and applied when the earthquake preparation zone is extended along a magnetic meridian. In the main part of the atmosphere up to a height of 50 km, we use an empirical conductivity model. Above 90 km we use the model, which is based on the empirical models IRI, MSISE and IGRF. In the rest layer the values of the components of the conductivity tensor are interpolated. The conjugate ionosphere is included to the model since the field-aligned conductivity in the magnetosphere is regarded as an infinite one. We solve the electric conductivity problem using Fourier transform at each height and numerically solve the systems of ordinary differential equations for the Fourier coefficients. The space distributions of the electric field strength and the current density are calculated. The current lines in both hemispheres are plotted. The electric field strength in the ionosphere is in the microvolt per meter range when it is about 100 mV/m in the air near ground. The known approximate estimates of the decrease of the electric field penetrating into the ionosphere with the decrease of the magnetic latitude are confirmed and detailed. The penetration of the electric field and current from the ground to the ionosphere through the atmospheric conductor cannot be a physical process which creates observed ionospheric precursors of earthquakes.