 |
| Titel |
Predictions on Optical Emissions Associated with Terrestrial Gamma-ray Flashes |
| VerfasserIn |
Sebastien Celestin, Wei Xu, Victor Pasko |
| Konferenz |
EGU General Assembly 2014
|
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250095418
|
| Publikation (Nr.) |
 EGU/EGU2014-10868.pdf |
|
|
|
|
|
| Zusammenfassung |
| Terrestrial Gamma-ray Flashes (TGFs) are high-energy photon bursts originating from the
Earth’s atmosphere. After their discovery in 1994 by the Burst and Transient Source
Experiment (BATSE) detector aboard the Compton Gamma-Ray Observatory [Fishman et al.,
Science, 264, 1313, 1994], this phenomenon has been further observed by the Reuven
Ramaty High Energy Solar Spectroscopic Imager (RHESSI) [Smith et al., Science, 307,
1085, 2005], the Fermi Gamma-ray Space Telescope [Briggs et al., JGR, 115, A07323, 2010]
and the Astrorivelatore Gamma a Immagini Leggero (AGILE) satellite [Marisaldi et
al., JGR, 115, A00E13, 2010]. Measurements have correlated TGFs with initial
development stages of normal polarity intracloud lightning that transports negative charge
upward (+IC) [e.g., Lu et al., GRL, 37, L11806, 2010; JGR, 116, A03316, 2011].
Recently, Østgaard et al. [GRL, 40, 2423, 2013] have reported for the first time
space-based observations of optical emissions from TGF-associated IC lightning
flashes.
The purpose of the present work is to predict the intensities of optical emissions resulting
from the excitation of air molecules by the large amount of low- and high-energy electrons
involved in TGF events based on two production mechanisms: relativistic runaway electron
avalanches (RREAs) [Dwyer and Smith, GRL, 32, L22804, 2005] and production of runaway
electrons by high-potential +IC lightning leaders [e.g., Celestin and Pasko, JGR, 116,
A03315, 2011; Xu et al., GRL, 39, L08801, 2012]. We use a Monte Carlo model to simulate
the propagation of electrons in either large-scale homogeneous electric fields sustaining
RREAs or highly inhomogeneous electric fields produced around the lightning
leaders tips region. A model similar to that described in [Liu and Pasko, JGR, 109,
A04301, 2004] is used to estimate intensities from the first and second positive band
systems of N2 and the first negative band system of N2+. The optical emissions
produced by RREAs are compared to those recently estimated by Dwyer et al. [GRL,
40, 4067, 2013]. We will specifically investigate the differences obtained between
optical emissions produced by both TGF production mechanisms considered as
they could be used to determine which is truly responsible for TGF production. |
|
|
|
|
|
|