A non-LTE radiative transfer model for infrared bands in the middle atmosphere. I. Theoretical basis and application to CO2 15 μm bands

An improved model for non-equilibrium radiative transfer processes in the middle atmosphere (40-120 km) is presented. Results from the model are compared to previously published results for the 15 μm bands of carbon dioxide and the relative importance of the various energy transfer mechanisms at work, including those involving overtone bands and isotopic species and pumping by sunlight during the day, are discussed. From the results, the importance to cooling rate calculations in dynamical or radiative equilibrium models of a wide range of processes can be assessed and the need for a fairly complete radiative transfer scheme can be seen. © 1986.