Ozone in the mesosphere and lower thermosphere

Abstract

One-dimensional photochemical diffusive model has been used to obtain the altitude and temporal variation of O₃ in the range of 50 to 150km height. More than 60 chemical reactions and photo-dissociatons of oxygen-hydrogen atmosphere are incorporated. Their contribution in the formation or distribution directly or indirectly, is critically examined.

In the altitude profile of O₃ concentration, it is observed that there is slight increase in concentration around 85km which is due to the increase in production rate at that height through the following reaction as: O+O₂+M→O₃+M (M=total atmospheric concentration) and the sharp decrease above 90km is also through the same reaction. Two altitude profiles of ozone concentration, one from photochemical equilibrium and other from non-equilibrium model are obtained. It is seen that in the mesosphere these two profiles are comparable. Further it is also seen that the average night time concentration is more than that in the day. Results obtained are compared with experimental values.