Discrete Spectrum of Ultralow-Frequency Oscillations of the Ionosphere

This work relates to the field of ultralow-frequency (ULF) spectroscopy of near-earth plasma. Our attention is focused on the Alfvén ionospheric resonator, the spectrum of which is a series of discrete lines. The aim of the study is to experimentally verify a well-defined theoretical prediction. Within the framework of an idealized resonator model, a hypothesis about the relationship between the frequencies of spectral lines has been formulated. To test the hypothesis, observations of ULF oscillations at the mid-latitude Mondy observatory were used. The result of the analysis confirmed the hypothesis that odd harmonics of the resonator discrete spectrum are observed on the earth’s surface. In conclusion, the possibilities of ULF spectroscopy for remote sensing of the ionosphere are briefly discussed.