Measurements of the stratospheric carbon dioxide concentration over Japan using a Balloon‐borne cryogenic sampler

Stratospheric air samples have been collected once per year since 1985 over Japan using a balloon‐borne cryogenic sampler and then analyzed for their CO₂ concentrations. The measurements showed high values of CO₂ in the lowest part of the stratosphere, then a decrease with height to 20.0–25.0 km, and almost constant values above this level. From the comparison with the results of our aircraft measurements in the upper troposphere and lower stratosphere, it is suggested that the vertical profile of stratospheric CO₂ over Japan is strongly related to transport processes that are associated with tropospheric air being introduced into the stratosphere in the tropical region and then moving poleward with different speeds at different heights. The average rate of the CO₂ increase from 1985 to 1991 was estimated to be 1.4 ppmv/year; this is similar to the rate found for the troposphere over the same period.