Ratio Between Discrete IAR Frequencies From Observations in the Solar Cycle 24

Abstract

Two types of standing Alfvén waves can exist in the ionospheric Alfvén resonator (IAR). The first of them (type 1) corresponds to the case when an antinode of oscillations of the magnetic field of a standing Alfvén wave occurs at the lower boundary of the resonator. The second type corresponds to the case when a node of magnetic field oscillations occurs at the lower boundary. The article proposes an original technique that makes it possible to experimentally determine which of the two indicated types is observed in the experiment. The methodology is based on the idea that in the first case the harmonics of oscillations are odd, i.e., are multiples of 3, 5, 7, and 9, while in the second case the harmonics are multiples of the fundamental frequency: 2, 3, 4, 5, and so on (type 2 of standing waves). Using ground-based observations of the IAR emissions at obs. Mondy from 2009 to 2019, we have shown that events with an odd ratio of harmonics are most often observed.