Stratospheric Determination of Effective Photodissociation Cross Sections for Molecular Oxygen: 191-204 nm
Final rept. 1 Oct 1982-30 Sep 1983
AIR FORCE GEOPHYSICS LAB HANSCOM AFB MA
Pagination or Media Count:
Balloon-borne spectrometer measurements of solar ultraviolet irradiance have been used to provide direct estimates of effective photodissociation cross-sections sigma sub i to the e power i 10Ta lambda interval for molecular oxygen appropriate for altitudes between 30 and 40 km. The calculations from which can be determined are based on an internally consistent, two-part analysis of ascent spectra. The fine resolution 02 absorption cross section derived from the fractional transmission between two altitudes is convolved with the calibrated insitu irradiance and then integrated over wavelength, yielding photodissociation rate coefficients J-values for the conditions of the flight 22 April 1981 at 33 N latitude and approximately 50 Deg solar zenith angle. The J-values are then decomposed into the signma i sub e and average attenuated irradiances for the selected wavelength intervals. Photochemical models which incorporate these altitude-dependent 02 cross sections will reasonably approximate both the local optical attenuation and the photodissociation rate coefficients, since the sigma i sub e have been calculated by a simultaneous solution of both the attenuation and the photodissociation equations.
- Atmospheric Physics