ANGEO Annales Geophysicae ANGEO Ann. Geophys. 1432-0576 Copernicus Publications Göttingen, Germany 10.5194/angeo-27-1313-2009 Magnetic-inclination effects in the spectral resonance structure of the ionospheric Alfvén resonator Bösinger T. 1 Ermakova E. N. 2 Haldoupis C. 3 Kotik D. S. 2 University of Oulu, Department of Physical Sciences, Oulu, Finland Radio Physical Institute, Nizhny Novgorod, Russia University of Crete, Physics Department, Heraklion, Crete, Greece 13 03 2009 27 3 1313 1320 Copyright: © 2009 T. Bösinger et al. 2009 This work is licensed under the Creative Commons Attribution 3.0 Unported License. To view a copy of this licence, visit https://creativecommons.org/licenses/by/3.0/ This article is available from https://angeo.copernicus.org/articles/27/1313/2009/angeo-27-1313-2009.html The full text article is available as a PDF file from https://angeo.copernicus.org/articles/27/1313/2009/angeo-27-1313-2009.pdf

Based on recent developments in the formalism governing the spectral resonance structures (SRS) of the Ionospheric Alfvén resonator (IAR) as observed on the Earth's surface, a numerical code was developed to investigate properties of SRS which can in particular be contributed to magnetic inclination effects. Among the theoretical findings are: 1) SRS is discernible in both orthogonal components, 2) the harmonic structure of SRS is not anymore over frequency equidistantly distributed, 3) the frequency scales of SRS differ in the two normal modes. The theoretically predicted properties could be found in the observations of a low latitude and some of them even in the data of a mid latitude station. The verification, however, is not as straight forward because the predicted effects do not only depend on magnetic inclination but also on the wave angle of the lightning induced electromagnetic wave <I>k</I>-vector with the normal to the magnetic meridian passing through the observation site. So far the formalism is simplified as it deals with a single source situation alone whereas the actual observation is a composite of excitations caused by an average of about 60 flashes of lightning operating all the time, world-wide.

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