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| Titel |
Influence of sprite streamers in the mesospheric chemical and thermal balance |
| VerfasserIn |
Francisco C. Parra-Rojas, Alejandro Luque, Francisco J. Gordillo-Vázquez |
| 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 |
250110659
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| Publikation (Nr.) |
 EGU/EGU2015-10684.pdf |
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| Zusammenfassung |
| We present new results to contribute to the fundamental understanding of the chemistry of
non-equilibrium plasmas produced by nighttime sprite streamers in the mesosphere and their
influence on the chemical composition and thermal evolution of the upper atmosphere. This
contribution describes the kinetic model used and the time evolution of the concentration of
many important species for the sprite and its afterglow through an upgrade of previous TLE
kinetic models [1], [2].
A one-dimensional self-consistent model has been developed to study the chemical and
thermal effects of a single sprite streamer in the Earth mesosphere. We have used sprite
streamer profiles with three different driving current durations (5 ms, 50 ms and 100 ms)
between 50 and 80 km of altitude and considering a kinetic scheme of air with 20 chemical
species.
Our model predicts strong increases in practically all the concentrations of the species
studied at the moment of the streamer head passage. Moreover, their densities remain high
during the streamer afterglow phase. The electron concentration can reach values of up
to 108 cm-3 in the three cases analyzed. The model also predicts an important
enhancement, of several orders of magnitude above ambient values, of nitrogen oxides
(NOx and N2O) and the considered metastables species (N2(A), O2(a), O2(b)).
Metastables are capable of storing energy for relatively long time (hundreds of
seconds).
On the other hand, we found that the 4.26 μm IR emission brightness of CO2 can exceed
in 4 orders of magnitude the threshold of visibility (1 MR) at low altitudes (< 65 km)
for the cases of intermediate (50 ms) and long (100 ms) driving currents. These
results suggest the possibility of detecting sprite IR emissions from space with
the appropriate instrumentation. Moreover, according to our model, the Meinel
emission brightness of N2+ could also reach the threshold of visibility below 50
km.
Finally, we found that the thermal impact of sprites in the Earth mesosphere is
proportional to the driving current duration. This produces variations of more than 40 K (in
the extreme case of a 100 ms driving current) at low altitudes (< 55 km) and at about 10
seconds after the streamer head.
[1] Gordillo-Vazquez, F. J., Air plasma kinetics under the influence of sprites, J. Phys. D,
41(23), 234016, doi:10.1088/0022-3727/41/23/234016, 2008.
[2] Parra-Rojas, F. C., A. Luque, and F. J. Gordillo-Vazquez, Chemical and electrical
impact of
lightning on the Earth mesosphere: The case of sprite halos, J. Geophys. Res., 118, 1–25,
doi:10.1002/jgra.50449, 2013a. |
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