The vertical distribution of CH4, N2O,CFC-12 and CFC-11 in the middle atmosphere at mid-latitudes

CH₄, N₂O, CFC-12 and CFC-11 data analysed from samples collected by means of cryogenic samplers from five balloon flights conducted during the 1982–1984 period, are presented. The vertical distributions of these gases show structures with dominant scale size of 16 ±2.5 km. The amplitude of the perturbation is larger for the species having steeper gradient. A comparison of the present results with the results of earlier measurements representing the period of 1977–1979 do not show any appreciable change in the mixing ratios of CH₄ and N₂O. However, an average tropospheric increase of (6.5±1)% per year is found for CFC-12 and CFC-11. This annual change in the mixing ratios of CFC-12 and CFC-11 is found to increase with height suggesting a time lag of about 6 years between the troposphere and the altitude region around 25 km. The average mixing ratios of CH₄ and N₂O are compared with the available satellite/spacelab data. This data set shows a satisfactory agreement with the present in situ measurements for the height region above 30 km.