Electromagnetic oscillations of the Earth's upper atmosphere (review)

Abstract

Abstract.A complete theory of low-frequency MHD oscillations of the Earth's weakly ionized ionosphere is formulated. Peculiarities of excitation and propagation of electromagnetic acoustic-gravity, MHD and planetary waves are considered in the Earth's ionosphere. The general dispersion equation is derived for the magneto-acoustic, magnetogravity and electromagnetic planetary waves in the ionospheric E-and F-regions. The action of the geomagnetic field on the propagation of acoustic-gravity waves is elucidated. The nature of the existence of the comparatively new largescale electromagnetic planetary branches is emphasized.

On the Features of Magnetogradient Planetary Waves in the Approximation of the Spherical Symmetry of the Ionosphere

“…If in the equations (2.3) and (2.4) we will pass on to the local Cartesian coordinate system ("standard" system [1,7]), taking into account 0 , 0 i < = and using the approximation…”

“…The perturbed values of velocity and induced magnetic field h together with the Maxwell's induction equation form the closed system [3,7]:…”

“…It is shown that for the *Address correspondence to this author at the Georgian Technical University, Institute of Cybernetics, Kostava street, 77, 0175, Tbilisi, Georgia; Tel: +99532-227-406; Fax: +99532-253-898; E-mails: jandieri@access.sanet.ge, jandieri_george@yahoo.com planetary scale wave processes, neglecting dissipation, compressibility and temperature stratification, the MHD equations of the ionosphere besides the well known hydrodynamic planetary Rossby waves contain both the slow (5 100 m s 1 ) ultra-low frequency (10 Generation of slow waves is connected with electrostatic dynamo field (wind mechanism), and generation of fast waves -with vortex electrical field and electromagnetic Ampere force. The fast electromagnetic planetary waves in the local Cartesian coordinate system ( -plane approximation) were first theoretically discovered in [6,7] and slow planetary waves in [6][7][8]. The latitudinal gradients of geomagnetic field play important role in dispersion equation of these waves.…”

“…Therefore, following the terminology of Chernogor [9] we'll term this new oscillating branch of the ionospheric resonator as magnetogradient planetary waves. The influence of curvature of the lines of force of the geomagnetic field, Rayleigh and ionic frictions on the magnetogradient planetary waves were investigated in [7,10]. Linear and nonlinear problems of propagation of these waves in the dissipative E-region of the ionosphere were solved in [11][12][13][14].…”

“…Below we will not take into account the effects of viscosity, compressibility and temperature stratification [3,15,16]. Experimental verifications of existence of the magnetogradient planetary waves at the ionospheric levels are given in [7,9,[17][18][19].…”