Discrete Spectrum of Ultralow-Frequency Oscillations of the Ionosphere

Potapov, A. S.; Guglielmi, A. V.; Klain, B. I.

doi:10.1109/tgrs.2021.3092738

Cited by 11 publications

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References 20 publications

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“…Совместные наблюдения в ионосфере и на Земле могли бы разрешить ряд вопросов по условиям прохождения волн к земной поверхности и их отражению от нижней границы резонатора и более точно определить положение этой границы. В частности, авторы работы [Potapov et al, 2021] обратили внимание на то, что частоты гармоник, имеющих узел электрического (и пучность магнитного) поля внизу (рис. 1, слева), образуют ряд нечетных чисел 1, 3, 5, 7 и т. д., и предположили, что только такие моды могут наблюдаться на земле.…”

Section: заключениеunclassified

Morphology and diagnostic potential of the ionospheric Alfvén resonator

Потапов

Polyushkina

Цэгмэд

2021

Solnechno-Zemnaya Fizika

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The layering of the ionosphere leads to the formation of resonators and waveguides of various kinds. One of the most well-known is the ionospheric Alfvén resonator (IAR) whose radiation can be observed both on Earth’s surface and in space in the form of a fan-shaped set of discrete spectral bands (DSB), the frequency of which changes smoothly during the day. The bands are formed by Alfvén waves trapped between the lower part of the ionosphere and the altitude profile bending of Alfvén velocity in the transition region between the ionosphere and the magnetosphere. Thus, IAR is one of the important mechanisms of the ionosphere-magnetosphere interaction. The emission frequency lies in the range from tenths of hertz to about 8 Hz — the frequency of the first harmonic of the Schumann resonance. The review describes in detail the morphology of the phenomenon. It is emphasized that the IAR emission is a permanent phenomenon; the probability of observing it is primarily determined by the sensitivity of the equipment and the absence of interference of natural and artificial origin. The daily duration of the DSB observation almost completely depends on the illumination conditions of the lower ionosphere: the bands are clearly visible only when the D layer is shaded. Numerous theoretical IAR models have been systematized. All of them are based on the analysis of the excitation and propagation of Alfvén waves in inhomogeneous ionospheric plasma and differ mainly in sources of oscillation generation and methods of accounting for various factors such as interaction of wave modes, dipole geometry of the magnetic field, frequency dispersion of waves. Predicted by all models of the cavity and repeatedly confirmed experimentally, the close relationship between DSB frequency variations and critical frequency foF2 variations serves as the basis for searching ways of determining in real time the electron density of the ionosphere from IAR emission frequency measurements. It is also possible to estimate the profile of the ion composition over the ionosphere from the data on the IAR emission frequency structure. The review also focuses on other results from a wide range of IAR studies, specifically on the results that revealed the influence of the interplanetary magnetic field orien tation on oscillations of the resonator, and on the facts of the influence of seismic disturbances on IAR.

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Section: заключениеunclassified

Morphology and diagnostic potential of the ionospheric Alfvén resonator

Потапов

Polyushkina

Цэгмэд

2021

Solnechno-Zemnaya Fizika

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“…Заметим, что в зависимости от контекста аббревиатура IAR используется для обозначения резонансных колебаний, а также ионосферного резонатора Альвена. Представление об IAR было теоретически обосновано и экспериментально подтверждено в серии работ [Беляев, Поляков, 1980;Поляков, Рапопорт, 1980;Поляков, Рапопорт, Трахтенгерц, 1983;Беляев и др., 1987;Belyaev et al, 1989;Potapov et al, 2014;Потапов, Полюшкина, Цэгмэд, 2021;Potapov, Guglielmi, Klain, 2022].…”

Section: Introductionunclassified

On the Spectrum of Ultra-Low-Frequency Oscillations of the Ionosphere in the Pc1 Range

2023

Геофиз.Исслед.

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The idea of Alfvén waves plays a key role in the theory of ultra-low-frequency (ULF) electromagnetic oscillations of cosmic origin. The article is dedicated to the 80th anniversary of the discovery of Alfvén waves. It focuses on the Ionospheric Alfvén Resonator, or IAR for short. ULF oscillations are excited in the IAR in the Pc1 range (0.2-5 Hz). When calculating the oscillation spectrum within the framework of the standard model, it is assumed that the IAR is an autonomous dynamic system. In contrast, in the presented article, the IAR is considered as a specific subsystem of the general system of Alfvén oscillations of geomagnetic field lines. In other words, authors proceed from the idea that the IAR, generally speaking, is not an autonomous oscillatory system. О спектре ультранизкочастотных колебаний ионосферы в диапазоне Рс1ГЕОФИЗИЧЕСКИЕ ИССЛЕДОВАНИЯ. 2023. Том 24. № 1 83The problem of the IAR spectrum is discussed in this article within the framework of the general problem of the spectrum of MHD oscillations of the Earth's magnetosphere. The corresponding Sturm-Liouville problem is formulated. Analytical solutions of the problem are considered in the Wentzel-Kramers-Brillouin approximation. The need for a numerical solution of the problem of the IAR spectrum is indicated in view of the rather complex distribution of the Alfvén velocity along geomagnetic field lines.

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Comparison of the Wave Structure of IAR Emission in the Mid-Latitude and Auroral Regions

Potapov

2024

IEEE Trans. Geosci. Remote Sensing

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Discrete Spectrum of Ultralow-Frequency Oscillations of the Ionosphere

Cited by 11 publications

References 20 publications

Morphology and diagnostic potential of the ionospheric Alfvén resonator

Morphology and diagnostic potential of the ionospheric Alfvén resonator

On the Spectrum of Ultra-Low-Frequency Oscillations of the Ionosphere in the Pc1 Range

Comparison of the Wave Structure of IAR Emission in the Mid-Latitude and Auroral Regions

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