Hydromagnetic Waves in the Magnetosphere and the Ionosphere PDF Download
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Author: Leonid S. Alperovich
Publisher: Springer Science & Business Media
ISBN: 1402066376
Category : Science
Languages : en
Pages : 437
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Book Description
Here is a fascinating text that integrates topics pertaining to all scales of the MHD-waves, emphasizing the linkages between the ULF-waves below the ionosphere on the ground and magnetospheric MHD-waves. It will be most helpful to graduate and post-graduate students, familiar with advanced calculus, who study the science of MHD-waves in the magnetosphere and ionosphere. The book deals with Ultra-Low-Frequency (ULF)-electromagnetic waves observed on the Earth and in Space.
Author: Leonid S. Alperovich
Publisher: Springer Science & Business Media
ISBN: 1402066376
Category : Science
Languages : en
Pages : 437
Get Book Here
Book Description
Here is a fascinating text that integrates topics pertaining to all scales of the MHD-waves, emphasizing the linkages between the ULF-waves below the ionosphere on the ground and magnetospheric MHD-waves. It will be most helpful to graduate and post-graduate students, familiar with advanced calculus, who study the science of MHD-waves in the magnetosphere and ionosphere. The book deals with Ultra-Low-Frequency (ULF)-electromagnetic waves observed on the Earth and in Space.
Author: Muhammad Abbas
Publisher:
ISBN:
Category : Magnetohydrodynamics
Languages : en
Pages : 125
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Book Description
The report is concerned with the analysis of hydromagnetic waves which are generated in various regions of the magnetosphere and propagated to the earth in the extremely low frequency spectrum. Two different aspects of the problem are investigated, namely, propagation through inhomogeneous regions of the ionosphere and propagation and excitation of waves in current carrying regions of the ionosphere and the magnetosphere. Propagation through inhomogeneous regions is studied by two different methods: Transmission coefficients for hydromagnetic waves are obtained by assuming a linearly varying inhomogeneous region and by transforming the wave equation into a hypergeometric equation such that various types of inhomogeneities can be handled (Epstein theory). Assuming a hydromagnetic wave incident from above and propagating parallel to the earth's magnetic field, power transmission coefficients are calculated for various times of day. Propagation of hydromagnetic waves through a current carrying plasma is investigated on the basis of macroscopic equations in which additional terms arising from the presence of a constant current density are included. A general dispersion relation for small amplitude waves is derived. For propagation normal to the steady magnetic field, when the currents are normal to both, the direction of propagation and the static magnetic field, it is found that amplification takes place. For longitudinal propagation with currents in the transverse plane, the propagation constant remains unaffected. For longitudinal propagation, with currents also along the direction of propagation, the propagation constant has a resonance at the ion-cyclotron frequency for both, right and left hand polarization. (Author).
Author: Richard Alexander Marshall
Publisher:
ISBN:
Category : Dissertations, Academic
Languages : en
Pages : 434
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Book Description
Author: Ilan Josip Rothmuller
Publisher:
ISBN:
Category : Ionospheric radio wave propagation
Languages : en
Pages : 334
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Book Description
Author: Carl Greifinger
Publisher:
ISBN:
Category : Magnetohydrodynamic waves
Languages : en
Pages : 55
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Book Description
In this report, the propagation through the ionosphere of low-frequency (1 cps) hydromagnetic waves is studied. The ionosphere is assumed to extend infinitely far in the upward direction and to terminate abruptly 80 km above a perfectly conducting flat earth. The charged particle density is assumed to be constant throughout the iono sphere, and the neutral particle density to vary exponentially with altitude. The coupled hydrodynamic and electromagnetic equations for the medium are linearized, and, with the approximations valid for low-frequency waves, the resulting system is shown to reduce to a second-order wave equation. A solution of this equation is obtained for a disturbance which is initially localized high in the ionosphere (i.e., at an altitude at which collisions of ions with neutrals can be neglected). The effects of the model ionosphere on hydromagnetic disturbances are contained in a dispersion relation. In particular, the ionosphere is found to possess certain characteristic frequencies, which appear as the roots of this dispersion relation. (Author).
Author: Gordon James MacDonald
Publisher:
ISBN:
Category : Atmosphere, Upper
Languages : en
Pages : 72
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Book Description
A disturbance in the exosphere generates waves in three partially separable modes. These modes are described by considering the vorticity about a line of force, the two-dimensional divergence of velocity in the plane perpendicular to the line of force, and the component of velocity along the line of force. The propagation of vorticity is one-dimensional and there is no geometrical attenuation; energy is lost only through the finite conductivity of the medium. The propagation of the longitudinal velocity component is almost one-dimensional but is heavily damped at high frequencies. In a gravitational field, the medium is no longer uniform and at low frequencies the modes are coupled in a complicated way. For parallel magnetic and gravitational fields, the vorticity mode is still separable and gravity leads to anisotropic dispersion in the other modes.-p.i.
Author: Gordon J. F. MacDonald
Publisher:
ISBN:
Category : Exosphere
Languages : en
Pages : 72
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Book Description
A disturbance in the exosphere generates waves in three partially separable modes. These modes are described by considering the vorticity about a line of force, the two-dimensional divergence of velocity in the plane perpendicular to the line of force, and the component of velocity along the line of force. The propagation of vorticity is one-dimensional and there is no geometrical attenuation; energy is lost only through the finite conductivity of the medium. The propagation of the longitudinal velocity component is almost one-dimensional but is heavily damped at high frequencies. In a gravitational field, the medium is no longer uniform and at low frequencies the modes are coupled in a complicated way. For parallel magnetic and gravitational fields, the vorticity mode is still separable and gravity leads to anisotropic dispersion in the other modes.
Author: Ian Stuart Dunlop
Publisher:
ISBN:
Category : Magnetohydrodynamics
Languages : en
Pages : 232
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Book Description
Author: David J. Knudsen
Publisher:
ISBN:
Category : Ionosphere
Languages : en
Pages : 440
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Book Description
Perturbation electric and magnetic fields carry in excess of 10(exp10) to 10(exp12) W of electrical power between the magnetosphere and high-latitude ionosphere. Most of this power is generated by the solar wind. The ionosphere at large spatial and temporal scales acts as a dissipative slab which can be characterized by its height-integrated Pedersen conductivity sigma p, so that the power flux into the ionosphere due to a quasi-static electric field E is given by sigma (pE2) The energy transferred to the ionosphere by time-varying electromagnetic fields in the form of Alfven waves is more difficult to calculate because density and conductivity gradients can reflect energy. Thus, field resonances and standing wave patterns affect the magnitude and altitude distribution of electrical energy dissipation. We use a numerical model to calculate the frequency-dependent electric field reflection coefficient of the ionosphere and show that the ionosphere does not behave as a simple resistive slab for electric field time scales less than a few seconds. Time variation of spacecraft-measured high-latitude electric and perturbation magnetic fields is difficult to distinguish from spatial structuring that has been Doppler-shifted to a non-zero frequency in the spacecraft frame. However, by calculating the frequency-dependent amplitude and phase relations between fluctuating electric and magnetic fields we are able to show that low frequency fields (
Author: S. P. Kuo
Publisher:
ISBN:
Category :
Languages : en
Pages : 121
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Book Description
The topics of investigation are divided into four general categories: (a) cavity modes of the magnetosphere resulting in the discrete spectrum of the resonant ultralow frequency waves; (b) a hydromagnetic code for the numerical study of the coupling of hydromagnetic waves in the dipole model of the magnetosphere; a theoretical model developed for explaining the phenomenon of plasma line over shoot observed in the ionospheric HF heating experiments; and thermal flamentation instability as the mechanism for generation of large scale field aligned ionospheric irregularities. For the first two topics, the hydromagnetic wave equations are analyzed analytically in cylindrical model of the magnetosphere and numerically in dipole model of the magnetosphere, respectively. While the steady state eigenvalue problem is studied in the first topic, the second topic is generalized to the boundary value problem considering the coupling between hydromagnetic waves in the realistic geometry of the magnetosphere. For the third topic, a nonlinear turbulent theory (resonance instability excited by a powerful high frequency in the ionosphere. For the last topic, the thermal nonlinearity gives rise to the mode-mode coupling; threshold field and the growth rate of the instability are derived. (jhd).
