Nonlinear frequency down-conversion of acoustic wave beams in the atmosphere and ionosphere under different types of modulation (regular item)

Grimalsky, V.; Rapoport, Yuriy; Tecpoyotl-Torres, M.; Ivantyshyn, O.; Nesterenko, A.

doi:10.1016/j.jastp.2021.105774

Cited by 2 publications

(1 citation statement)

References 57 publications

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“…In the approximation of geometrical optics, relations were obtained that allow us to estimate fluctuations in neutral density and vertical displacement of the neutral gas volume at reflection heights from fluctuations in the amplitudes of radio waves. An influence on the atmosphere and ionosphere by nonlinear AGWs caused by tsunami has been modeled theoretically in [ 25 ]; corresponding influence caused by ground-based acoustic generator has been established experimentally in [ 26 ] and theoretically in [ 27 , 28 , 29 , 30 , 31 ]. As shown in the review by [ 32 ], a study of VLF waves in the WGEI allows us to cover the wide range of the physical processes in the system of Atmosphere–Ionosphere, in particular “lightning-induced short term perturbations; extra-terrestrial radiation bursts; energetic particle precipitation events; solar eclipses; lower atmospheric waves penetrating into the D-region; sudden stratospheric warming events; the annual oscillation; the solar cycle; and, finally, the potential use of VLF narrow-band measurements as an anthropogenic climate change monitoring technique”.…”

Section: Introductionmentioning

confidence: 99%

Spectral Analysis and Information Entropy Approaches to Data of VLF Disturbances in the Waveguide Earth-Ionosphere

Rapoport

Reshetnyk

Grytsai

et al. 2022

Sensors

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Very low frequency (VLF) signals are considered as an important tool to study ionosphere disturbances. We have studied variations in signal amplitude of the Japanese JJI transmitter received by a network of eight Japan stations. The distinctions between characteristics of daytime and nighttime disturbances are considered. Signal processing based on spectral analysis is used to evaluate typical periodicities in the VLF signals in the time range from minutes to hours. In particular, we have retrieved quasi-wave oscillations of the received signal with periods of 4–10 and 20–25 min, which can be associated with atmospheric gravity waves excited by the solar terminator, earthquakes or other reasons. In addition, oscillations at periods of 3–4 h are observed, probably, caused by long-period gravity waves. We also calculate the information entropy to identify main details in daily VLF variations and influence of solar flares. It is shown that the information entropy increases near sunrise and sunset with seasonal variation, and that solar flares also lead to the growth in information entropy. A theoretical interpretation is given to the typical features of ultra-low frequency modulation of VLF electronagnetic wave spectra in Waveguide Earth-Ionosphere, found by processing the experimental data.

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Section: Introductionmentioning

confidence: 99%

Spectral Analysis and Information Entropy Approaches to Data of VLF Disturbances in the Waveguide Earth-Ionosphere

Rapoport

Reshetnyk

Grytsai

et al. 2022

Sensors

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The Typical ELF/VLF Electromagnetic Wave Activities in the Upper Ionosphere Recorded by the China Seismo-Electromagnetic Satellite

Hu,

Zhima,

Wang

et al. 2024

Remote Sensing

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Driven by the scientific objective of geophysical field detection and natural hazard monitoring from space, China launched an electromagnetic satellite, which is known as the China Seismo-Electromagnetic Satellite (CSES-01), on 2 February 2018, into a circular sun-synchronous orbit with an altitude of about 507 km in the ionosphere. The CSES-01 has been in orbit for over 6 years, successfully exceeding its designed 5-year lifespan, and will continually operate as long as possible. A second identical successor (CSES-02) will be launched in December 2024 in the same orbit space. The ionosphere is a highly dynamic and complicated system, and it is necessary to comprehensively understand the electromagnetic environment and the physical effects caused by various disturbance sources. The motivation of this report is to introduce the typical electromagnetic waves, mainly in the ELF/VLF band (i.e., ~100 Hz to 25 kHz), recorded by the CSES-01 in order to call the international community for deep research on EM wave activities and geophysical sphere coupling mechanisms. The wave spectral properties and the wave propagation parameters of those typical EM wave activities in the upper ionosphere are demonstrated in this study based on wave vector analysis using the singular value decomposition (SVD) method. The analysis shows that those typical and common natural EM waves in the upper ionosphere mainly include the ionospheric hiss and proton whistlers in the ELF band (below 1 kHz), the quasiperiodic (QP) emissions, magnetospheric line radiations (MLR), the falling-tone lightning whistlers, and V-shaped streaks in the ELF/VLF band (below 20 kHz). The typical artificial EM waves in the ELF/VLF band, such as power line harmonic radiation (PLHR) and radio waves in the VLF band, are also well recorded in the ionosphere.

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Nonlinear frequency down-conversion of acoustic wave beams in the atmosphere and ionosphere under different types of modulation (regular item)

Cited by 2 publications

References 57 publications

Spectral Analysis and Information Entropy Approaches to Data of VLF Disturbances in the Waveguide Earth-Ionosphere

Spectral Analysis and Information Entropy Approaches to Data of VLF Disturbances in the Waveguide Earth-Ionosphere

The Typical ELF/VLF Electromagnetic Wave Activities in the Upper Ionosphere Recorded by the China Seismo-Electromagnetic Satellite

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