Atmospheric electricity has been detected in all gaseous giants of our solar system and is therefore likely present also in extrasolar planets. Building upon measurements from Saturn and Jupiter, we investigate how the electromagnetic pulse emitted by a lightning stroke affects upper layers of a gaseous giant. This effect is probably significantly stronger than that on Earth. We find 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.”
[1] A one-dimensional electrochemical model is developed to describe, in a self-consistent way, the response of the Earth mesosphere to different types of lightning discharges between 50 and 87 km of altitude. This model is applied to the case of sprite halos, one of the most common types of transient luminous events (TLE). We have studied the time-altitude evolution of more than 20 chemical species. Our model predicts an increase of up to 70 cm -3 in the electron density from ambient electron density values between 55 and 81 km of altitude in the +CG lightning cases and a negligible mesospheric electron density perturbation in the -CG lightning case. For all the +CG and some -CG (200 kAkm . On the other hand, for the first positive group of N 2 the calculated emission brightness exceeds the threshold of visibility (1 MR) for a halo of 100 km of diameter at an altitude of 77 km for all the CG lightning discharges studied (except for the -CG case with 100 kAkm current peak) and for relatively lower altitudes when +CG lightnings are considered. Moreover, the calculated concentration of the metastables N 2 (A 3 † + u ) and O( 1 D) exhibit an enormous enhancement (of more than 10 orders of magnitude) over their ambient values that, for +CG, remains high (5-7 orders of magnitude above ambient values) for long times (up to 500 s), below 55 km.
A one‐dimensional self‐consistent model has been developed to study the chemical and thermal effects of a single sprite streamer in the Earth's 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 more than 90 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 concentration of electrons 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 and several metastables species. On the other hand, we found that the 4.26 μm IR emission brightness of CO2 can reach 10 GR 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. Finally, we found that the thermal impact of sprites in the Earth's 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 s after the streamer head.
[1] We have studied laboratory low pressure (0.1 mbar Ä p Ä 2 mbar) glow air discharges by optical emission spectroscopy to discuss several spectroscopic techniques that could be implemented by field spectrographs, depending on the available spectral resolution, to experimentally quantify the gas temperature associated to transient luminous events (TLEs) occurring at different altitudes including blue jets, giant blue jets, and sprites. Laboratory air plasmas have been analyzed from the near UV (300 nm) to the near IR (1060 nm) with high (up to 0.01 nm) and low (2 nm) spectral resolution commercial grating spectrographs and by an in-house intensified CCD grating spectrograph that we have recently developed for TLE spectral diagnostic surveys with ' 0.45 nm spectral resolution. We discuss the results of lab tests and comment on the convenience of using one or another technique for rotational (gas) temperature determination depending on the altitude and available spectral resolution. Moreover, we compare available low resolution (3 nm Ä Ä 7 nm) N 2 1PG field recorded sprite spectra at 53 km (' 1 mbar), and resulting vibrational distribution function, with 1 mbar laboratory glow discharge spectrum ( = 2 nm) and synthetic sprite spectra from models. We found that while the relative population of N 2 (B 3 … g , v = 2 -7) in sprites and laboratory produced air glow plasmas are similar, the N 2 (B 3 … g , v = 1) vibrational level in sprites is more efficiently populated (in agreement with model predictions) than in laboratory air glow plasmas at similar pressures.Citation: Parra-Rojas, F. C., M. Passas, E. Carrasco, A. Luque, I. Tanarro, M. Simek, and F. J. Gordillo-Vázquez (2013), Spectroscopic diagnostics of laboratory air plasmas as a benchmark for spectral rotational (gas) temperature determination in TLEs,
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