Stratospheric distribution of HCN from far infrared observations

Far infrared limb thermal emission measurements of the earth's stratosphere were made with a high resolution spectrometer on a balloon payload launched from Palestine, Texas, on October 5, 1982. Several limb sequences of a portion of the observed spectra have been analyzed for retrieval of the stratospheric HCN profile from a number of spectral lines in the 32 to 56 cm−1 region. The mixing ratio profile in the 20 to 37 km altitude range has been retrieved with 2σ uncertainties of ∼ 15 to 20% and with an altitude resolution of ∼ 4-5 km. The HCN volume mixing ratio is found to be ∼ 139 pptv at 20 km, 127 pptv at 25 km, and increasing to 172 pptv at 37 km. The results are compared with measurements by other groups and with photochemical model calculations reported in the literature.