Mesospheric ozone from the CRISTA-1 satellite experimental data: 1. Method of profile determination and its accuracy

A method for simultaneous retrievals of the profiles of the ozone content and of the nonequilibrium populations of the O-3 vibrational states (i.e., for the vibrational temperatures) from the outgoing IR radiation measured along tangent paths in the absence of local thermodynamic equilibrium (the non-LTE conditions) is described. This method requires no simulation of the processes controlling the nonequilibrium populations of vibrational states. On the basis of numerical experiments and error-matrix calculations, the accuracy of this method is studied as applied to the interpretation of the spectra recorded in the 10-mu m range during the 1994 CRISTA satellite experiment. This method allows retrievals of the vertical ozone profiles in the height range 40-90 km. For the daytime conditions, the retrieval errors are 3-15% below 65 km and 20-47% in the height ran(ye 70-90 km. For the nighttime conditions, the retrieval errors are 4-13% below 70 km and 17-24% in the overlying layers. The method allows retrieval of vibrational -temperature profiles for six groups of ozone vibrational states (001, 100), (011, 110), (002, 101, 200), (021, 120), (012, 111, 210), and (003, 102, 201), as well as for the 000 11 state of carbon dioxide molecules. The errors of vibrational-temperature retrieval depend heavily on states and times of day and vary in a wide range (1-40 K): nevertheless, they are significantly lower than the vibrational -temperature uncertainty caused by the non-LTE effect (the difference between the vibrational and kinetic temperatures). Some results of the numerical experiments and of processing individual measurements are given as examples. The retrieved ozone profiles are compared to the data of the HALOE experiment.