Abstract
The present study focuses on the middle atmospheric ozone variability using 14 (2002-2015) years of Sounding of the Atmosphere using Broadband Emission Radiometry onboard Thermosphere Ionosphere Mesosphere Energetics and Dynamics satellite observations over the mid-latitude regions of northern and southern hemispheres. It is noted that ozone buildup starts late winter, and peaks during the springtime and gradually decreases in summer to autumn transitional period in both the hemispheres. The time series of ozone indicates the dominant annual and semi-annual oscillations in the middle atmosphere. The annual oscillation (AO) is found to be dominant over both the hemispheres, while the semi-annual oscillation (SAO) peaks at two different altitude regions: 30-60 km and 80-100 km. Further, the amplitude of AO is much significant than SSAO and MSAO. It is also noted another significant oscillation that peaks at 4 months in the altitude range 60-80 km. The strength of these oscillations at different sites is studied by comparing it with the zonal mean spectrum to assess the longitudinal asymmetry. It is found that the longitudinal asymmetry is more significant in the northern hemisphere than the southern hemisphere. This can be attributed to the differences in the land (elevated topographies in the northern hemisphere) and primarily ocean (in southern hemisphere) contrast that further contributes to the differences in the strength of the vertically propagating planetary-scale waves modulating the middle atmospheric ozone.