The Radiophysical Research Institute (NIRFI), based in Nizhny Novgorod, Russia, is a research institute that conducts basic and applied research in the field of radiophysics, radio astronomy, cosmology and radio engineering. It is also known for its work in solar physics, sun-earth physics as well as the related geophysics. It also does outreach for the Russian education system. It was formed in 1956 as the Radiophysical Research Institute of the (Soviet) Ministry of Education and Science..
During the active experiment FENICS-2024 on the Kola Peninsula using a decommissioned power transmission line as a horizontal radiating antenna, ultra-low-frequency signals of the 1–6 Hz range were recorded at magnetic stations located from ~1600 km to ~2100 km from the transmission line with normalized amplitudes from ~0.3 fT/A to ~0.8 fT/A. Observational results are compared with approximate analytical estimates of the magnetic field excited by the magnetic dipole. The calculations turned out to be in qualitative agreement with the observational results. To assess the possible response in the upper ionosphere, a numerical model of the ULF field in the atmosphere and ionosphere generated by the horizontal surface current was employed. The model is based on solving the system of Maxwell equations in the vertically inhomogeneous atmosphere and ionosphere. The fundamental feature of this model is that it correctly takes into account the contribution of ionospheric waveguide propagation. The observational results supported by numerical simulation have shown the potential of active experiments of the new type for signal generation for large-area magnetotelluric sounding and for modification of near-Earth plasma with artificial signals.
The study analyzes the results of low-orbital satellite radio tomography measurements of the spatial structure of artificial electron-density variations Earth’s topside ionosphere excited during modification of the F2 layer of the mid-latitude ionosphere by high-power O-polarized HF radio waves emitted by the SURA heating facility. The article considers the characteristics of the cavity with a reduced plasma density that forms near the reflection height of a high-power HF radio wave, ducts with increased plasma density that form in the topside ionosphere due to displacement of plasma from the heated region along the geomagnetic field, and various wave disturbances induced at ionospheric heights. In addition, the properties of detected plasma density disturbances of a special nature in the vertical column above the central part of the disturbed region of the ionosphere are also investigated. The sizes of the studied irregularities are from several tens to several hundreds of kilometers, and the area of their existence goes far beyond the region of resonance interaction of a high-power O-polarized radio wave with ionospheric plasma near its reflection height, where the most intense artificial ionospheric turbulence is excited.
Radio frequency emission from thunderclouds is analysed on the base of measurements over a wide frequency range with a high temporal resolution. This emission mainly consists of short sub-microsecond bi-polar pulses. Characteristics of the pulses are studied at different stages of lightning discharge development as well as for events does not leading to lightning.
The paper presents the results of experiments on the impact on the ionosphere by high-power high-frequency radio emission from heating facilities on disturbance of the lower ionosphere with the creation of artificial periodic irregularities (APIs) of the ionospheric plasma. The objective of the experiments was to extend the method of studying of the ionosphere using APIs on three heating facilities located in high (HAARP), mid latitude (SURA) and low latitude (Arecibo) zones.
