Long Path Atmospheric Ozone Absorption in the 9–10-μ Region Observed from a Balloon-Borne Spectrometer

Abstract

A balloon-borne spectrometer was used to measure the atmospheric absorption of solar radiation in the 9–10-μ region as a function of altitude. Among the numerous spectra recorded, several were made with very long optical paths above the troposphere obtained from floating altitude (~30 km) while the sun set. When the experimental results are compared with calculated spectra, based on line by line parameters of the ν₃ and ν₁ fundamentals of ordinary ozone, ¹⁶O₃, combined with the Curtis-Godson approximation, large discrepancies are found for the long path spectra. It is shown that the hot bands ν₃ + ν₂ − ν₂ and ν₃ + ν₃ − ν₃ of the ¹⁶O₃, and the ν₃ fundamentals of the isotopic species ¹⁶O¹⁸O¹⁶O and ¹⁶O¹⁶O¹⁸O, can contribute significant absorption for long paths such as obtained in this experiment. Such long paths also give rise to significant absorptions by the ν₃ − ν₁ and the ν₃ − 2ν₂° bands of CO₂. Including these weak bands in the calculated spectra leads to good agreement with the observed data.