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‐ to 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 nonlocal thermodynamic equilibrium radiative transfer model. Our simulations predict a strong production of CO2 in the (001) vibrational level which lasts at least 40 s before falling to background concentrations. This leads to enhanced emissions in the long‐wavelength infrared, around 1,000 cm−1, and midwavelength infrared, around 2,300 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 1 order of magnitude lower if propagated until the troposphere. From the two spectral bands, the 1,000‐cm−1 one could be detected more easily than the 2,300‐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 1,000‐cm−1 band could be detected from 20–40 km of altitude.

A lack of observable quantities renders it generally difficult to confront models of Space Weather with experimental data and drastically reduces the forecast accuracy. This is especially true for the region of Earth’s atmosphere between altitudes of 90 km and 300 km, which is practically inaccessible, except by means of remote sensing techniques. For this reason auroral emissions are an interesting proxy for the physical processes taking place in this region. This paper describes two future space missions, AMICal Sat and ATISE, that will rely on CubeSats to observe the aurora. These satellites will perform measurements of auroral emissions in order to reconstruct the deposition of particle precipitations in auroral regions. ATISE is a 12U CubeSat with a spectrometer and imager payloads. The spectrometer is built using the micro-Spectrometer-On-a-Chip (μSPOC) technology. It will work in the 370–900 nm wavelength range and allow for short exposure times of around 1 s. The spectrometer will have six lines of sight. The joint imager is a miniaturized wide-field imager based on the Teledyne-E2V ONYX detector in combination with a large aperture objective. Observation will be done at the limb and will enable reconstruction of the vertical profile of the auroral emissions. ATISE is planned to be launched in mid 2021. AMICal Sat is a 2U CubeSat that will embed the imager of ATISE and will observe the aurora both in limb and nadir configurations. This imager will enable measuring vertical profiles of the emission when observing in a limb configuration similar to that of ATISE. It will map a large part of the night side auroral oval with a resolution of the order of a few km. Both the spectrometer and imager will be calibrated with a photometric precision better than 10% using the moon as a wide-field, stable and extended source. Ground-based demonstrators of both instruments have been tested in 2017 in Norway and Svalbard. Even though some issues still need to be solved, the first results are very encouraging for the planned future space missions. Data interpretation will be done using the forward Transsolo code, a 1D kinetic code solving the Boltzmann equation along a local vertical and enabling simulation of the thermospheric and ionospheric emissions using precipitation data as input.

International audienceWe study the effects of Sprites on the atmospheric chemistry and radiances. We use the code SAMM2 to model the excitation of the ambient atmosphere. Then we explain how we will include a sprite model