A study has been made of the theories of atmospheric refraction and anomalous dispersion for the purpose of assisting the interpretation of measurements of atmospheric gases by the solar occultation technique, and a computer program has been written to calculate a theoretical occultation spectrum in the vicinity of an isolated absorption line. A brief general discussion of the pertinent physical parameters, such as refractive index, line intensities and line shapes, is included. The theory is applied to several infrared absorption lines of water vapor, particularly the 1404.988 cm-1 line, assuming a pure Lorentz line shape. This assumed line shape is only valid for altitudes below about 20 km, and will be modified in future calculations. The numerical calculations have been performed with computer programs written in the Fortran IV language, in which the refractive and dispersive angular deviations of the ray path and the absorption with or without instrumental corrections are evaluated. The absorption is obtained by integration along the curvilinear path of the radiation, taking into account the dependence of the refractive index and absorption coefficient on altitude. The basic profiles of pressure and temperature with altitude are taken from the U. S. Standard Atmosphere [1962] and the basic water vapor mixing ratio profile from Reiter [1971].
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