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| Titel |
Probing atmospheric electric fields in thunderstorms through radio emission from cosmic-ray induced air showers |
| VerfasserIn |
Gia Thi Ngoc Trinh, Pim Schellart, Stijn Buitink, Arthur Corstanje, Ute Ebert, Emilio Enriquez, Heino Falcke, Jörg R. Horandel, Anna Nelles, Jörg Paul Rachen, Casper Rutjes, Olaf Scholten, Sander ter Veen, Satyendra Thoudam |
| Konferenz |
EGU General Assembly 2015
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 17 (2015) |
| Datensatznummer |
250107301
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| Publikation (Nr.) |
 EGU/EGU2015-6997.pdf |
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| Zusammenfassung |
| Energetic cosmic rays impinging on the atmosphere create a particle avalanche called
extensive air shower. In the leading plasma of this shower electric currents are induced that
generate the emission of radio waves which have been detected with LOFAR, an array
of a large number of simple antennas primarily developed for radio-astronomy
observations.
Events have been collected under fair-weather conditions as well as under atmospheric
conditions where thunderstorms occur. Of the 196 radio pulses detected under fair weather
conditions, the intensity as well as the polarization can be reproduced rather accurately for
192 event with the standard model [1] using a superposition of a geomagnetically-induced
transverse current and charge excess contributions. This indicates that the emission process is
well understood.
For most of the events measured under thunderstorm conditions as well as the 4 fair
weather events we observe large differences in intensity and polarization pattern from the fair
weather model. We observe for these events that it is not possible to get a good fit of the
measured intensity pattern. For the same events the dominant polarization direction differs
from the orientation observed in the fair-weather condition.
We show that this difference is a consequence of atmospheric electric fields. We also
show that the effects of atmospheric electric fields are understood, and that from the
cosmic-ray radio footprint the atmospheric electric field can be deduced. Therefore,
measuring radio emission from cosmic ray extensive air showers during thunderstorm
conditions provides a new tool to probe the atmospheric electric fields present in
thunderclouds.
[1] P. Schellart et al., arXiv:1406.1355 [astro-ph.HE]. |
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