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

A balloon-borne spectrometer was used to measure the atmospheric absorption of solar radiation in the 9-10-micro 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 nu(3) and nu(1) fundamentals of ordinary ozone, (16)O(3), combined with the Curtis-Godson approximation, large discrepancies are found for the long path spectra. It is shown that the hot bands nu(3), + nu(2), - nu(2), and nu(3), + nu(3), - nu(3), of the (16)O(3), and the nu(3) fundamentals of the isotopic species (16)O(18)O(16)O and (16)O(16)O(18)O, can contribute significant absorption for long paths such as obtained in this experiment. Such long paths also give rise to significant absorptions by the nu(3) - nu(1) and the nu(3) - 2nu(2) degrees bands of CO(2). Including these weak bands in the calculated spectra leads to good agreement with the observed data.