Abundance of methane in the atmosphere above 20 kilometers

During a balloon flight made December 7, 1967, infrared solar spectra in the region around 1300 cm−1 were obtained at numerous altitudes up to 30 km. This spectral region contains a strong absorption band due to atmospheric methane. Comparisons between the observed absorption and the absorption predicted using a line-by-line calculation have been used to determine the amount of methane in the atmosphere above the tropopause. These determinations indicate that the methane concentration decreases by as much as a factor of 5 above the tropopause.