This paper deals with the problem of the creation of an artificial ionized layer (AIL) in the upper atmosphere by using a powerful nanosecond microwave discharge. The results of laboratory investigations of the processes taking place at ai breakdown by the pulses of nanosecond duration and of the effects influencing the parameters of AIL are presented. It is shown that the nanosecond discharge can be a powerful source of ionization and electronically excited molecules. The dynamics of electronically excited molecules and their influence on character of plasma decay, the regime of maintenance, and the optical radiation of AIL are considered. The possibility of using AIL for the generation of induced UV radiation and creation of an atmosphere laser with distant microwave pumping is analyzed. The results of the investigation of the dynamics of the creation of ozone and nitrogen oxides in the pulse-periodical regime close to the suggested one for the AIL maintenance are presented. The possibility of using AIL for the regeneration of ozone and clearing of the atmosphere is discussed. ¿ American Geophysical Union 1994