Electromagnetic Field in the Upper Ionosphere From ELF Ground‐Based Transmitter

The feasibility of detection of electromagnetic response in the upper ionosphere to ground large‐scale extremely low frequency (ELF) transmitters (e.g., submarine communication systems) by low‐orbiting satellites is discussed. Several times when the DEMETER satellite (660 km) was in the vicinity of the ELF transmitter on the Kola Peninsula, the electric and magnetic sensors operating in a burst mode detected a narrowband 82‐Hz emission. The same emission associated with the ELF transmitter was observed by a ground‐based magnetometer. We modeled the rate of the ELF wave energy leakage into the upper ionosphere from an oscillating 82‐Hz linear current with an infinite length suspended above a high‐resistive ground. A realistic altitudinal profile of the plasma parameters has been reconstructed with the use of the IRI ionospheric model. The modeled amplitudes and polarization of electromagnetic response of the upper ionosphere are in reasonable agreement with the properties of emission recorded by the satellite. Key Points An 82‐Hz emission from ground ELF transmitter was recorded in the upper ionosphere by satellite DEMETER Spectral power of electric and magnetic components in the nightside ionosphere is about several nT2/Hz and tens of (μV/m)2/Hz Modeling the electromagnetic response to oscillating line current above a high‐resistive crust matches the observational result