Decrease in CO₂ mixing ratio observed in the stratosphere

Abstract

Air samples, collected cryogenically at different heights of the stratosphere, were analysed for carbon dioxide with an IR absorption technique. Supplementary tropospheric air samples were taken aboard commercial airliners. The results reported here show that the CO₂ mixing ratio is not constant with altitude but rather decreases in the stratosphere, by about 7 p.p.m.v., between the tropopause and 33 km. One conclusion is that recently increased concentrations of CO₂ in the troposphere have not propagated far into the stratosphere.