CO2 NONLOCAL THERMODYNAMIC-EQUILIBRIUM RADIATIVE EXCITATION AND INFRARED DAYGLOW AT 4.3 MU-M - APPLICATION TO SPECTRAL INFRARED ROCKET EXPERIMENT DATA

Infrared radiative excitation in non-local thermodynamic equilibrium ( non-LTE) regions of the Earth's atmosphere for the nu3-mode vibrationa lly excited states of CO2 under sunlit conditions and the resulting 4. 3-mum limb radiance are calculated using a line-by-line (LBL) radiativ e transfer model. Excited-state population densities and the correspon ding vibrational temperature profiles are calculated for the important emitting states using a model which includes radiative absorption and emission as well as various collisional processes. The quenching of O (1D) by N2 has a greater impact on these population densities than has been previously reported in the literature. Integrated radiance in a limb view for the 4.3-mum bands is calculated from the model and compa red with sunlit earthlimb measurements obtained by the Spectral Infrar ed Rocket Experiment (SPIRE). Solar pumping is the dominant excitation process for the 4.3-mum emitting states in the daytime. The major con tribution to the total limb radiance for tangent heights of 55-95 km i s made by the fluorescent states at approximately 3600 cm-1 which abso rb sunlight at 2.7 mum and then emit preferentially at 4.3 mum. The pr edicted radiance is in good agreement with the SPIRE measurements for all tangent heights in the 50- to 130-km range. This is the first deta iled comparison of results of a full line-by-line non-LTE radiative tr ansfer calculation with 4.3-mum earthlimb radiance data.