Observations by DEMETER of Man-Made MF Waves Escaping From the Ionosphere

摘要

DEMETER was a low altitude satellite on a polar and circular orbit devoted to the study of ionospheric perturbations in relation with seismic activity. Its scientific payload with waves and plasma measurements also allows to study man-made waves. The aim of this paper is to check the conditions of apparition of these man-made waves in the MF range (300 kHz, 3 MHz). These waves normally propagate in the Earth-ionosphere waveguide, but it is shown that they can escape above the ionosphere when there is a decrease in the electron density. This meanly occurs at the ionospheric troughs when they are close to inhabited areas, but also above the South Atlantic Anomaly and when the magnetic activity is high.