Numerical methods for the generation of empirical and analytical transmittance functions with applications to...

A numerical approach is taken in the study of two methods commonly used in the development of band models for the calculation of gaseous molecular transmittance in the IR region. The first method considered is for the determination of a discrete transmittance function without the use of an analytical band model. This method is then modified assuming a piecewise continuous function to provide for interpolation between the discrete points. The second method relaxes restrictions inherent to the first and assumes an analytical function over the entire range of transmittance values. Although the theory is generally applicable to other gaseous absorbers, it is specifically applied to 20-cm(-1) resolution data for the major bands of the atmospheric trace gases SO(2), NH(3), NO, and NO(2). The spectral parameters are listed for the convenience of model users at 5-cm(-1) intervals throughout the bands.