Effects of temperature dependence of reaction N₂(A³ S⁺_u) + O ongreenline dayglow emission

Abstract. The greenline dayglow emission profiles measured by the Wind Imaging Interferometer (WINDII) on the Upper Atmosphere Research Satellite (UARS) are modelled using recently proposed revisions to the temperature dependent rate coefficient of the reaction N₂ (A³ S⁺_u ) + O in the glow model. The volume emission rates of greenline dayglow emissions are calculated using the Hinteregger et al. (1981) and Tobiska (1991) solar flux models. It is found that the average modelled profiles obtained using the Hinteregger et al. (1981) solar flux model with the temperature dependent rate coefficient and a quantum yield of 0.36 for the reaction N₂ (A³ S⁺_u ) + O agree to within 8% of the observed profiles in the thermospheric peak region, which shows significant improvement over the earlier results (20% smaller than WINDII results) obtained using the temperature independent reaction rate coefficient. On the other hand, the average modelled profiles obtained with a temperature dependent rate coefficient in the Tobiska (1991) solar flux model are about 12% higher than the WINDII results, whereas with the temperature independent rate coefficient the results are about 10% smaller than the WINDII results in the thermospheric peak region. The present study reveals that the emission profiles obtained using the Hinteregger et al. (1981) solar flux model, along with the temperature dependent rate coefficient and a quantum yield of 0.36 for the reaction N₂ (A³ S⁺_u ) + O in glow model, reproduce the thermospheric emission peak as observed by WINDII, a capability which eluded earlier models. These findings support the newly discovered temperature dependence of the rate coefficient of re-action N₂ (A³ S⁺_u ) with O.

Key words. Ionosphere (ionization mechanisms; modeling and forecasting; general or miscellaneous)