CO2 thermal infrared signature following a sprite event in the mesosphere

Abstract : Sprites are a potential thermal infrared radiation source in the stratosphere and mesosphere through molecular vibrational excitation. We developed a plasma‐chemical model to compute the vibrational kinetics induced by a sprite streamer in the 40‐70 km altitude range until several tens of seconds after the visible flash is over. Then, we computed the consecutive time‐dependent thermal infrared spectra that could be observed from the stratosphere (from a balloon platform), high troposphere (from an aircraft) and low troposphere (aircraft or altitude observatory) using a non‐local thermodynamic equilibrium radiative transfer model. Our simulations predict a strong production of CO2 in the (001) vibrational level which lasts at least 40 seconds before falling to background concentrations. This leads to enhanced emissions in the long wavelength infrared, around 1000 cm‐1, and mid wavelength infrared, around 2300 cm‐1. The maximum sprite infrared signatures (sprite spectra minus background spectra) reach several 10‐7 W/sr/cm2/cm‐1 after propagation through the mesosphere and stratosphere, to an observer located at 20‐40 km of altitude. This maximum signal is about one order of magnitude lower if propagated until the troposphere. From the two spectral bands, the 1000 cm‐1 one could be detected more easily than the 2300 cm‐1 one, which is more affected by atmospheric absorption (CO2 self‐trapping at all altitudes, and H2O, mostly in the troposphere). With a sufficiently sensitive instrumentation, mounted in an open stratospheric balloon platform for example, the 1000 cm‐1 band could be detected from 20 – 40 km of altitude.
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Contributor : Catherine Cardon <>
Submitted on : Tuesday, September 18, 2018 - 6:37:18 PM
Last modification on : Wednesday, September 4, 2019 - 2:22:04 PM

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Frédéric Romand, Anne Vialatte, Laurence Croizé, Sébastien Payan, M. Barthelemy. CO2 thermal infrared signature following a sprite event in the mesosphere. Journal of Geophysical Research Space Physics, American Geophysical Union/Wiley, 2018, 123 (9), pp.8039-8050. ⟨10.1029/2018JA025894⟩. ⟨insu-01876789⟩

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