Simulation of mesospheric-composition disturbances under the action of high-altitude discharges (sprites)

Recent measurements show that a mesospheric electric discharge (sprite) can provoke disturbances in the chemical composition of the mesosphere. In this paper, we propose a plasmachemical system of equations which allows one to describe the complex relationship among chemical components during the discharge. Disturbances of the mesospheric ion composition are analyzed under the night-time and daytime conditions at an altitude of 75 km, which is typical of the sprite initiation and at an altitude of 85 km where the diffuse region of discharge is usually observed. The most probable scenarios of development of the electric-field and electron-temperature disturbances, which are characteristic of the diffusive and streamer regions of the sprite, are simulated. The value and characteristic time of disturbances of the main ion components (O₂ ⁺, NO⁺, H₃O⁺, H₅O₂ ⁺, and N₂ ⁺) are evaluated. The obtained values of the electron-density disturbances are in agreement with experimental and theoretical data. It was established that the sprite series, which are recorded over the vast stratified regions of mesoscale convection systems, can lead to generation of comparatively long-lived disturbances in the ion composition of mesospheric plasma.