MODELING OF NON-LTE LIMB SPECTRA OF IR OZONE BANDS FOR THE MIPAS SPACE EXPERIMENT

A new model for calculating the populations of the ozone vibrational s tates under non-LTE (Local Thermodynamic Equilibrium) conditions is pr esented. In the model, 23 vibrational levels of the O-3 molecule, as w ell as three vibrational levels of the O-2 molecule and two vibrationa l levels of the N-2 molecule, are considered. The radiative transfer a t the break-down of LTE was treated explicitly for 150 000 ro-vibratio nal transitions. The populations obtained were used to calculate limb radiances in various spectral regions of the 4.8 and 9.6 mu m bands. T est retrievals of O-3 vertical volume mixing ratio (VMR) profiles with a radiance model disregarding non-LTE were performed in order to the potential impact of non-LTE effects on the retrieval of the O-3 abunda nces from MIPAS (Michelson Interferometer for Passive Atmospheric Soun ding) measurements. (C) 1998 Elsevier Science Ltd. All rights reserved .