Spectral Characteristics of the Geomagnetic Field Associated with the Equatorial Electrojet & Counter-Electro jet in the Indian Region

Abstract

Using the indices of the equatorial electrojet and the counter-electrojet in the Indian region, 20-yr long time series are formed and are subjected to spectral analysis by the fast Fourier transform technique. The 11-yr solar cycle line is prominently seen followed by the semi-annual line in the electrojet spectrum and the annual line in the counter-electrojet spectrum. The assumption, regarding the complete removal of disturbance field of extra-ionospheric origin in the electrojet field, in deriving the indices is supported by the absence of the 27-day and 13.5-day lines. The line corresponding to the lunar semi-monthly tide is found to be significant in both the spectra.