Height profiles of the amplitude and relaxation time of artificial periodic irregularities in the D region

Height profiles of the amplitude and relaxation time of artificial periodic irregularities (APIs) in the D region are calculated in a model of aeronom ic processes with one negative oxygen ion and a model of neutral atmosphere incorporating the concentrations of minor components: excited oxygen in th e (1)Delta (g) state and atomic oxygen. Comparison of computational results with experimental profiles indicates their good agreement. It is shown tha t the upper boundary of APIs at an altitude of similar to 80 km is due to a n increase in the concentration of atomic oxygen, and that it can serve as an indicator of the lower boundary of the region containing atomic oxygen. At altitudes of 55-65 km, the profiles are controlled by the temperature an d density of the atmosphere.