These investigations confirm the fact that in the stratosphere the ozone is considerably influenced by dynamical processes and it is a good indicator of them. In this context the main objectives of the proposed study are: 1) to investigate the possible relationship between stratospheric ozone perturbations and the temperature enhancement in the upper mesosphere, observed by Shepherd et al. (2001); 2) to examine whether changes in ozone, concomitant with the phenomenon, take place and how and when they would be manifested; and 3) to investigate the stratospheric ozone behaviour during the equinox atmospheric transition in the North Hemisphere, for better understanding of the middle atmosphere dynamics.