Non-Thermal Nitric Oxide Formation in the Earth’s Polar Atmosphere

Auroral events are the prominent manifestation of solar/stellar forcing on planetary atmospheres because they are closely related to the stellar energy deposition by and evolution of planetary atmospheres. A numerical kinetic Monte Carlo model was developed with the aim to calculate the steady-state energy distribution functions of suprathermal N(S-4) atoms in the polar upper atmosphere formed due to the precipitation of high-energy auroral electrons in the N-2-O-2 atmospheres of rocky planets in solar and exosolar planetary systems. This model describes on the molecular level the collisions of suprathermal N(S-4) atoms and atmospheric gas taking into account the stochastic nature of collisional scattering at high kinetic energies. It was found that the electron impact dissociation of N-2 is an important source of suprathermal N atoms, significantly increasing the non-thermal production of nitric oxide in the auroral regions of the N-2-O-2 atmospheres of terrestrial-type planets.