EarthRef.org Reference Database (ERR) -- Koppers & Murtagh 1996

In recent studies on the photolysis of ozone the triplet channel has been given much attention as a possible extra ozone source. The vibrationally excited oxygen molecules produced can either be quenched to heat the atmosphere or photolysed at longer wavelengths than normally possible for O2. The latter potentially lowers the fraction of solar energy that is converted to heat. Lack of experimental data to accurately estimate this fraction and the relatively small contribution to the total heating has been used to justify neglect of this effect. However, recent information on the quantum yield of excited oxygen as function of wavelength from ozone dissociation makes it possible to calculate the atmospheric heating efficiency in the ozone triplet channel in a more quantitative fashion. With the new quantum yield data the atmospheric heating efficiency in the triplet channel deviates from unity only above 80 km where the magnitude of the deviation is strongly dependent on the quantum yield. However, the large yield into the singlet channel masks any deviations from unit in the triplet channel. Therefore the current results indicate that previous work, which assumed unity heating efficiency for the triplet channel in the whole altitude range, is within 4% of a detailed calculation. Below 80 km the current results are consistent with previous work. ¿ American Geophysical Union 1996 In recent studies on the photolysis of ozone the triplet channel has been given much attention as a possible extra ozone source. The vibrationally excited oxygen molecules produced can either be quenched to heat the atmosphere or photolysed at longer wavelengths than normally possible for O2. The latter potentially lowers the fraction of solar energy that is converted to heat. Lack of experimental data to accurately estimate this fraction and the relatively small contribution to the total heating has been used to justify neglect of this effect. However, recent information on the quantum yield of excited oxygen as function of wavelength from ozone dissociation makes it possible to calculate the atmospheric heating efficiency in the ozone triplet channel in a more quantitative fashion. With the new quantum yield data the atmospheric heating efficiency in the triplet channel deviates from unity only above 80 km where the magnitude of the deviation is strongly dependent on the quantum yield. However, the large yield into the singlet channel masks any deviations from unit in the triplet channel. Therefore the current results indicate that previous work, which assumed unity heating efficiency for the triplet channel in the whole altitude range, is within 4% of a detailed calculation. Below 80 km the current results are consistent with previous work. ¿ American Geophysical Union 1996