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| Titel |
Giant elves: Lightning-generated electromagnetic pulses in giant planets. |
| VerfasserIn |
Alejandro Luque Estepa, Daria Dubrovin, Francisco José Gordillo-Vázquez, Ute Ebert, Francisco Carlos Parra-Rojas, Yoav Yair, Colin Price |
| 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 |
250110600
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| Publikation (Nr.) |
 EGU/EGU2015-10618.pdf |
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| Zusammenfassung |
| We currently have direct optical observations of atmospheric electricity in the two
giant gaseous planets of our Solar System [1-5] as well as radio signatures that
are possibly generated by lightning from the two icy planets Uranus and Neptune
[6,7].
On Earth, the electrical activity of the troposphere is associated with secondary electrical
phenomena called Transient Luminous Events (TLEs) that occur in the mesosphere and lower
ionosphere. This led some researchers to ask if similar processes may also exist in other
planets, focusing first on the quasi-static coupling mechanism [8], which on Earth is
responsible for halos and sprites and then including also the induction field, which is
negligible in our planet but dominant in Saturn [9].
However, one can show that, according to the best available estimation for lightning
parameters, in giant planets such as Saturn and Jupiter the effect of the electromagnetic pulse
(EMP) dominates the effect that a lightning discharge has on the lower ionosphere above
it.
Using a Finite-Differences, Time-Domain (FDTD) solver for the EMP we found [10] that
electrically active storms may create a localized but long-lasting layer of enhanced
ionization of up to 103 cm-3 free electrons below the ionosphere, thus extending the
ionosphere downward. We also estimate that the electromagnetic pulse transports 107 J
to 1010 J toward the ionosphere. There emissions of light of up to 108 J would
create a transient luminous event analogous to a terrestrial elve. Although these
emissions are about 10 times fainter than the emissions coming from the lightning
itself, it may be possible to target them for detection by filtering the appropiate
wavelengths.
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lightning, Nature, 280, 794, doi:10.1038/280794a0.
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Breneman, W. J. Borucki, and The Galileo SSI Team (1999), Galileo images of lightning on
Jupiter, Icarus, 142, 306–323, doi:10.1006/icar.1999.6195.
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Vasavada, and J. M. Barbara (2004), Lightning on Jupiter observed in the Hα line by the
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Voyager 2, Nature, 323, 605–608, doi:10.1038/323605a0.
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possibility of sprites in the atmospheres of other planets, J. Geophys. Res., 114, E09002,
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[9] Dubrovin, D., A. Luque, F. J. Gordillo-Vázquez, Y. Yair, F. C. Parra-Rojas, U. Ebert,
and C. Price (2014), Impact of lightning on the lower ionosphere of Saturn and possible
generation of halos and sprites, Icarus, 241, 313–328, doi:10.1016/j.icarus.2014.06.025.
[10] Luque, A., D. Dubrovin, F. J. Gordillo-Vázquez, U. Ebert, F. C. Parra-Rojas, Y. Yair,
and C. Price (2014), Coupling between atmospheric layers in gaseous giant planets due to
lightning-generated electromagnetic pulses, J. Geophys. Res. Space Physics, 119,
doi:10.1002/2014JA020457. |
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