Response of the ionosphere to the seismic trigerred acoustic waves: electron density and electromagnetic fluctuations | INSTITUT DE PHYSIQUE DU GLOBE DE PARIS

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  Response of the ionosphere to the seismic trigerred acoustic waves: electron density and electromagnetic fluctuations

Type de publication:

Journal Article

Source:

Geophysical Journal International, Volume 176, Ticket 1, p.1-13 (2009)

ISBN:

0956-540X

Numéro d'accès:

WOS:000261883400001

URL:

http://onlinelibrary.wiley.com/doi/10.1111/j.1365-246X.2008.03818.x/abstract;jsessionid=1C81859D9D078200C3B6A8187FDD38B1.d03t04

Mots-clés:

UMR 7154 ; Geophysique spatiale et planétaire ; N° Contribution : 2373 ; Ionosphere/atmosphere interactions; Earthquake dynamics

Résumé:

We study the excitation of low-frequency (0.001-10 Hz) electromagnetic and density fluctuations in the ionosphere during the passage of seismic triggered acoustic waves (AWs). The study involves the generation of ionospheric currents by AWs and subsequent perturbations of the electromagnetic fields and ion and electron density. In this study, the non-local analysis of the fluctuations is carried out in the framework of hydromagnetic theory. Our objective is to examine the spatial and frequency distributions of these fluctuations and to compare them qualitatively with the available observations. The dynamics of both electrojet and F region of ionosphere are included. Also included are the effects of the dip-angle variations of the Earth's magnetic field. Significant anisotropy and inhomogeneities are noted in the fluctuations. The amplitudes of current and magnetic field fluctuations are found to be maximum in the F region where ion inertia is large enough to support the plasma waves and where electron number density and acoustic wave amplitudes are also large. The density fluctuations also follow similar trends. Both electromagnetic and density fluctuations are large in the latitude region where the acoustic wave vibration parallel to the Earth's magnetic field is large. The fluctuations have the tendency to be maximum in the 0.1-1 Hz frequency range. In this range, AWs driven currents and electromagnetic fluctuations may become of order of mu Am-2, nV m(-1) and nT, respectively in the F region.