Modeling ELF waves in the non-uniform Earth-ionosphere cavity

2021 ◽  
Author(s):  
Tamas Bozoki ◽  
Erno Pracser ◽  
Gabriella Satori ◽  
Andrzej Kulak ◽  
Janusz Mlynarczyk ◽  
...  
Keyword(s):  
Electromagnetic Waves ◽  
Numerical Solutions ◽  
Model Development ◽  
Resonance Field ◽  
Low Frequency ◽  
Relative Difference ◽  
Telegraph Equation ◽  
Theoretical Description ◽  
Inversion Algorithm ◽  
The Earth

<p>Below 100 Hz, in the lowest part of the extremely low frequency (ELF, 3 Hz - 3 kHz) band lightning-radiated electromagnetic waves propagate with extremely low attenuation (roughly below 1 dB/Mm) within the Earth-ionosphere waveguide which makes possible the formation of global electromagnetic resonances, known as Schumann resonances (SRs). The most commonly used description of this resonance field assumes a uniform Earth-ionosphere cavity, i.e. that the propagation conditions for ELF waves are practically the same on the dayside and nightside hemispheres, which is the most vulnerable simplification of these models. </p><p>In this work we present two different forward models for SRs that take into consideration the day-night asymmetry of the Earth-ionosphere cavity and are based on the analytical and numerical solutions of the two-dimensional telegraph equation (TDTE). We present numerical tests showing that the two models produce practically the same output, i.e. the relative difference between them is less than 0.4%. The conspicuous conformity between the outputs establishes not only the correctness of the formalisms but the correctness of the implementations (the coding) as well. To the best of the authors’ knowledge this is the first work that verifies this conformity between the two independent solutions. </p><p>We also compare our stationary models with time-dependent solutions of the TDTE as the stationarity of the resonance field may represent the next most vulnerable simplification that needs to be dismissed to approach a more realistic theoretical description of SRs. All these steps in model development serve our aim to infer global lightning activity based on multi-station ELF measurements by applying a sophisticated inversion algorithm.</p>

scholarly journals Model of the propagation of very low-frequency beams in the Earth–ionosphere waveguide: principles of the tensor impedance method in multi-layered gyrotropic waveguides

2020 ◽  
Vol 38 (1) ◽  
pp. 207-230
Author(s):  
Yuriy Rapoport ◽  
Vladimir Grimalsky ◽  
Viktor Fedun ◽  
Oleksiy Agapitov ◽  
John Bonnell ◽  
...  
Keyword(s):  
Optical Waveguides ◽  
Electromagnetic Waves ◽  
Low Frequency ◽  
Signal Propagation ◽  
Wide Frequency Range ◽  
Impedance Method ◽  
Very Low Frequency ◽  
The Earth ◽  
Tensor Impedance ◽  
Electromagnetic Beams

Abstract. The modeling of very low-frequency (VLF) electromagnetic (EM) beam propagation in the Earth–ionosphere waveguide (WGEI) is considered. A new tensor impedance method for modeling the propagation of electromagnetic beams in a multi-layered and inhomogeneous waveguide is presented. The waveguide is assumed to possess the gyrotropy and inhomogeneity with a thick cover layer placed above the waveguide. The influence of geomagnetic field inclination and carrier beam frequency on the characteristics of the polarization transformation in the Earth–ionosphere waveguide is determined. The new method for modeling the propagation of electromagnetic beams allows us to study the (i) propagation of the very low-frequency modes in the Earth–ionosphere waveguide and, in perspective, their excitation by the typical Earth–ionosphere waveguide sources, such as radio wave transmitters and lightning discharges, and (ii) leakage of Earth–ionosphere waveguide waves into the upper ionosphere and magnetosphere. The proposed approach can be applied to the variety of problems related to the analysis of the propagation of electromagnetic waves in layered gyrotropic and anisotropic active media in a wide frequency range, e.g., from the Earth–ionosphere waveguide to the optical waveband, for artificial signal propagation such as metamaterial microwave or optical waveguides.

Analytical versus numerical solutions of the nonlinear fractional time–space telegraph equation

2021 ◽  
pp. 2150324
Author(s):  
Mostafa M. A. Khater ◽  
Dianchen Lu
Keyword(s):  
Analytical Solutions ◽  
Electromagnetic Waves ◽  
Numerical Scheme ◽  
Numerical Solutions ◽  
Telegraph Equation ◽  
Scatter Matrix ◽  
B Spline ◽  
Stable Property ◽  
Time Space ◽  
Matrix Distribution

In this paper, the stable analytical solutions’ accuracy of the nonlinear fractional nonlinear time–space telegraph (FNLTST) equation is investigated along with applying the trigonometric-quantic-B-spline (TQBS) method. This investigation depends on using the obtained analytical solutions to get the initial and boundary conditions that allow applying the numerical scheme in an easy and smooth way. Additionally, this paper aims to investigate the accuracy of the obtained analytical solutions after checking their stable property through using the properties of the Hamiltonian system. The considered model for this study is formulated by Oliver Heaviside in 1880 to define the advanced or voltage spectrum of electrified transmission, with day-to-day distances from the electrified communication or the application of electromagnetic waves. The matching between the analytical and numerical solutions is explained by some distinct sketches such as two-dimensional, scatter matrix, distribution, spline connected, bar normal, filling with two colors plots.

scholarly journals STUDY THE BIOPOTENTIAL PARAMETER FOR DETECTION OF SEISMIC AND ENVIORNMENTAL CHANGES IN INDIAN REGION

2021 ◽  
Vol 4 (2) ◽  
Author(s):  
Rudraksh Tiwari ◽  
Vinod Kuumar Kushwah
Keyword(s):  
Electromagnetic Waves ◽  
Environmental Changes ◽  
Low Frequency ◽  
Live Cells ◽  
Dielectric Parameters ◽  
Terrestrial Environment ◽  
Tectonic Processes ◽  
The Earth ◽  
Atmospheric Variations ◽  
Potential Signal

The changes in the magnetic flux generated (electric, magnetic and electromagnetic waves) on the surface of earth due to sudden changes is a matter of discussion. These emissions occur along the fault line generated due to geological and tectonic processes. When sudden changes occur in the environment due to seismic and atmospheric variations, these sensing was observed by creatures and human bodies because the animals and trees adopt the abnormal signals and change the behavior. We have analyzed the changing behavior of recorded signal by live sensors (i.e. banyan tree). So we use the deep rooted and long age’s banyan tree. Banyan tree (long ages) in which root has been working as a live sensor and record the geological and environmental changes. We record the low frequency signals which propagated through solar-terrestrial environment affect directly the root system of the banyan tree and changes has been observed by live sensors. Then, VLF signal ma(y propagate to the earth-ionosphere waveguide. We have also analyzed the different parameters of live cells which is inbuilt in latex of the tree, so we record the dielectric parameters of green stem latex and found some parameters i.e., dielectric constant (ε) and dielectric loss (ε’) of various trees to verify these natural hazards and found good correlation.  Therefore, we can say by regularly monitoring the bio-potential signal and dielectric properties of banyan tree we can able to find the precursory signature of seismic hazards and environmental changes.

On the upper frequency limit of whistler mode waves observed by low-altitude spacecraft

2020 ◽  
Author(s):  
Frantisek Nemec ◽  
Ondřej Santolík ◽  
Michel Parrot
Keyword(s):  
Magnetic Field ◽  
Electromagnetic Waves ◽  
Low Frequency ◽  
Realistic Model ◽  
Wave Intensity ◽  
Frequency Limit ◽  
Whistler Mode ◽  
The Earth ◽  
Whistler Mode Waves ◽  
Low Altitude

<p>Frequency-latitude plots of electromagnetic wave intensity in the very low frequency range (VLF, up to about 20 kHz) observed by the low altitude DEMETER spacecraft are analyzed. Apart from electromagnetic waves generated by plasma instabilities in the magnetosphere, a significant portion of the detected wave intensity comes from ground-based lightning activity and VLF military transmitters. These whistler mode waves are observed not only close to source locations, but also close to their geomagnetically conjugated points. There appears to be an upper frequency limit of such emissions, where the wave intensity substantially decreases. Its frequency roughly corresponds to half of the equatorial electron cyclotron frequency at a respective magnetic field line, suggesting a relation to wave ducting in ducts with enhanced density. However, it seems to exhibit a non-negligible longitudinal dependence and it is different during the day than during the night. We use a realistic model of the Earth’s magnetic field to explain the observed variations. We interpret the observations in terms of ducted/unducted wave propagation, and we compare the wave intensities in the source hemisphere with those measured in the hemisphere geomagnetically conjugated.</p>

scholarly journals Study the bio-potential parameter for the detection of seismic and environmental changes in Indian region

2021 ◽  
Vol 4 (2) ◽  
Author(s):  
Rudraksh Tiwari ◽  
Vijay S Katta ◽  
Vinod Kuumar Kushwah ◽  
Mulayam Singh Gaur ◽  
Priti Dimri
Keyword(s):  
Electromagnetic Waves ◽  
Environmental Changes ◽  
Low Frequency ◽  
Live Cells ◽  
Dielectric Parameters ◽  
Terrestrial Environment ◽  
Tectonic Processes ◽  
The Earth ◽  
Atmospheric Variations ◽  
Potential Signal

The changes the magnetic flux generated (electric, magnetic and electromagnetic waves) on the surface of earth due to sudden changes is a matter of discussion. These emissions occur along the fault line generated due to geological and tectonic processes. When sudden changes occur in the environment due to seismic and atmospheric variations, these sensing was observed by creatures and human bodies because the animals and trees adopt the abnormal signals and change the behavior. We have analyzed the changing behavior of recorded signal by live sensors (i.e., banyan tree). So we use the deep-rooted and long-aged banyan tree. The root of banyan tree (long-aged) has been working as a live sensor to record the geological and environmental changes. We record the low frequency signals propagated through solar-terrestrial environment which directly affect the root system of the banyan tree and changes that have been observed by live sensors. Then, very low frequency (VLF) signal may propagate to the earth-ionosphere waveguide. We have also analyzed the different parameters of live cells which is inbuilt in latex of the tree, so we record the dielectric parameters of green stem latex and found some parameters i.e., dielectric constant (ε) and dielectric loss (ε’) of various trees to verify these natural hazards and found good correlation. Therefore, we can say by regularly monitoring the bio-potential signal and dielectric properties of banyan tree and we are able to find the precursory signature of seismic hazards and environmental changes.

Seti Space Missions

1997 ◽  
Vol 161 ◽  
pp. 761-776 ◽  
Author(s):  
Claudio Maccone
Keyword(s):  
Electromagnetic Waves ◽  
Space Missions ◽  
Gravitational Lens ◽  
The Sun ◽  
Space Antenna ◽  
Focal Distance ◽  
Large Space ◽  
The Earth ◽  
Space Antennas ◽  
New Space

AbstractSETI from space is currently envisaged in three ways: i) by large space antennas orbiting the Earth that could be used for both VLBI and SETI (VSOP and RadioAstron missions), ii) by a radiotelescope inside the Saha far side Moon crater and an Earth-link antenna on the Mare Smythii near side plain. Such SETIMOON mission would require no astronaut work since a Tether, deployed in Moon orbit until the two antennas landed softly, would also be the cable connecting them. Alternatively, a data relay satellite orbiting the Earth-Moon Lagrangian pointL2would avoid the Earthlink antenna, iii) by a large space antenna put at the foci of the Sun gravitational lens: 1) for electromagnetic waves, the minimal focal distance is 550 Astronomical Units (AU) or 14 times beyond Pluto. One could use the huge radio magnifications of sources aligned to the Sun and spacecraft; 2) for gravitational waves and neutrinos, the focus lies between 22.45 and 29.59 AU (Uranus and Neptune orbits), with a flight time of less than 30 years. Two new space missions, of SETI interest if ET’s use neutrinos for communications, are proposed.

Scattering of electromagnetic waves by hybrid waves in a two-electron-temperature plasma

1991 ◽  
Vol 46 (1) ◽  
pp. 99-106 ◽  
Author(s):  
S. K. Sharma ◽  
A. Sudarshan
Keyword(s):  
Growth Rate ◽  
Electron Temperature ◽  
High Frequency ◽  
Electromagnetic Waves ◽  
Low Frequency ◽  
Lower Hybrid ◽  
Stimulated Scattering ◽  
Coupled Modes ◽  
Temperature Plasma ◽  
Electrostatic Perturbation

In this paper, we use the hydrodynamic approach to study the stimulated scattering of high-frequency electromagnetic waves by a low-frequency electrostatic perturbation that is either an upper- or lower-hybrid wave in a two-electron-temperature plasma. Considering the four-wave interaction between a strong high-frequency pump and the low-frequency electrostatic perturbation (LHW or UHW), we obtain the dispersion relation for the scattered wave, which is then solved to obtain an explicit expression for the growth rate of the coupled modes. For a typical Q-machine plasma, results show that in both cases the growth rate increases with noh/noc. This is in contrast with the results of Guha & Asthana (1989), who predicted that, for scattering by a UHW perturbation, the growth rate should decrease with increasing noh/noc.

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