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| Titel |
Experimental simulation of satellite observations of 100 kHz radio waves from relativistic electron beams above thunderclouds |
| VerfasserIn |
M. Füllekrug, C. Hanuise, M. Parrot |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1680-7316
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 11, no. 2 ; Nr. 11, no. 2 (2011-01-24), S.667-673 |
| Datensatznummer |
250009191
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| Publikation (Nr.) |
 copernicus.org/acp-11-667-2011.pdf |
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| Zusammenfassung |
| Relativistic electron beams above thunderclouds emit
100 kHz radio waves which illuminate the Earth's
atmosphere and near-Earth space. This contribution aims to clarify
the physical processes which are relevant for the spatial spreading of
the radio wave energy below and above the ionosphere and thereby
enables an experimental simulation of satellite observations of 100 kHz
radio waves from relativistic electron beams above thunderclouds. The
simulation uses the DEMETER satellite which observes
100 kHz radio waves from fifty terrestrial Long Range Aid
to Navigation (LORAN) transmitters. Their mean luminosity patch in the
plasmasphere is a circular area with a radius of 300 km
and a power density of 22 μW/Hz as observed at
660 km height above the ground. The luminosity patches
exhibit a southward displacement of 450 km with respect
to the locations of the LORAN transmitters. The displacement is
reduced to 150 km when an upward propagation of the
radio waves along the geomagnetic field line is assumed. This residual
displacement indicates that the radio waves undergo
150 km sub-ionospheric propagation prior to entering
a magnetospheric duct and escaping into near-Earth space. The residual
displacement at low (L < 2.14) and high (L > 2.14)
geomagnetic latitudes ranges from 100 km to
200 km which suggests that the smaller inclination of
the geomagnetic field lines at low latitudes helps to trap the radio
waves and to keep them in the magnetospheric duct. Diffuse luminosity
areas are observed northward of the magnetic conjugate locations of
LORAN transmitters at extremely low geomagnetic latitudes
(L < 1.36) in Southeast Asia. This result suggests that the
propagation along the geomagnetic field lines results in a spatial
spreading of the radio wave energy over distances of
1 Mm. The summative assessment of the electric field
intensities measured in space show that nadir observations of
terrestrial 100 kHz radio waves, e.g., from relativistic
electron beams above thunderclouds, are attenuated by at least
50 dB when taking into account a transionospheric
attenuation of 40 dB. |
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