Modeling ELF Electromagnetic Field in the Upper Ionosphere From Power Transmission Lines

Abstract

The expected magnitude of extralow-frequency (ELF) electromagnetic response in the upper ionosphere to ground large-scale power transmission lines at low Earth orbit (LEO) is modeled. The full-wave system of Maxwell's equations is numerically solved in a realistic ionosphere whose parameters have been reconstructed with the use of the International Reference Ionosphere (IRI) model. We have calculated the altitudinal structure in the atmosphere and ionosphere of electromagnetic field and Poynting flux excited by an oscillating 50/150 Hz linear current suspended above the ground. The leakage rate into the upper ionosphere was shown to increase during nighttime hours and above a high-resistive crust. The amplitudes of electromagnetic power line emission (PLE) detected by LEO satellites correspond to the unbalanced power line current intensity of about 1-10 A, depending on the crust resistivity.

Electromagnetic Response of the Mid‐Latitude Ionosphere to Power Transmission Lines

“…The PLE intensity was generally larger during the night than during the day. Numerical modeling in Fedorov et al (2020) has shown that this day-night asymmetry is caused by a larger wave attenuation during the propagation through the daytime ionosphere. PLE at both 50 and 60 Hz were observed by electric antenna of low-latitude C/NOFS satellite (Pfaff et al, 2014).…”

“…The electromagnetic ELF field in the upper ionosphere generated by a near‐ground power line was shown to depend on the ionospheric density and resistivity of the underlying crust (Fedorov et al., 2020). In that study the amplitudes of electric and magnetic fields in the ionosphere and atmosphere at various altitudes have been numerically calculated for day/night ionospheric conditions and crust resistivities under the vertical geomagnetic field.…”

“…The increase of ground conductivity by 2 orders of magnitude from S/m up to S/m resulted in about order of magnitude decrease of excited electric field in the upper ionosphere above the source. A comparison of the ELF transmission through the daytime and nighttime ionosphere showed that penetration through the ionosphere during nighttime is more efficient than during daytime, though the difference is not very large (Fedorov et al., 2020). All these results were obtained in the model with a vertical .…”

“…In contrast to VLF emitters (like radio transmitters or lightning strokes) a source of PLE cannot be modeled as a point dipole, but its finite scale, often exceeding the height of the lower ionosphere (∼ km) must be taken into an account. As a first step, in our previous study (Fedorov et al., 2020) a numerical model of electromagnetic response of a realistic ionosphere to a near‐ground infinite line current has been elaborated. However, it was assumed that geomagnetic field is vertical, so this model can be applied at high latitudes only.…”

“…B is vertical, so this model can be applied at high latitudes only. In this paper, we advance the theoretical model of Fedorov et al (2020) by the possibility to consider arbitrary geomagnetic field inclination and power line orientation. The account for an arbitrary geomagnetic field inclination makes the problem significantly more complicated because the medium parameters become not axially symmetric.…”