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Ann. Geophys., 23, 3301-3311, 2005
www.ann-geophys.net/23/3301/2005/
© European Geosciences Union 2005
ELF magnetospheric lines observed by DEMETER
M. Parrot1, F. Němec2, O. Santolík2, and J. J. Berthelier3
1LPCE/CNRS, 3A Avenue de la Recherche Scientifique, 45071 Orléans cedex 2, France
2Charles University, Faculty of Mathematics and Physics, Prague, Czech Republic
3CETP, Observatoire de Saint Maur, 4 Avenue de Neptune, 94107 Saint Maur des Fossés cedex, France
Abstract. The influence of man-made activity on the ionosphere may be very
important. The effects induced by the Power Line Harmonic Radiation (PLHR)
may change the natural wave activity and/or the ionospheric plasma
components. One goal of the ionospheric satellite DEMETER launched in June
2004 is to study the ionospheric perturbations which could be related to
this anthropogenic activity. As the first step, the paper presents Tram
Lines (TL) which have been observed on board DEMETER with frequency intervals
close to 50 Hz or 16 Hz 2/3 (the current frequency of the railways). When it
is observable the frequency drift of these TL is very slow. It is shown that
these events occur during periods of strong or moderate magnetic activity. A
wave propagation analysis indicates that the TL observed below the low
cutoff frequency of the hiss which is simultaneously present are coming from
a region below the satellite. The conclusion is that these TL observed by
DEMETER are produced by PLHR or radiation of railways lines.
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